Bandit Alley
GENERAL MOTORCYCLE FORUMS => GENERAL MECHANICAL & TECHNICAL => Topic started by: rmack87 on February 01, 2012, 11:39:34 AM
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Howdy folks. Long time reader, first post. Me and two buddies bought three bandit400s last christmas...we have been riding them in the highlands of lesotho. slowly some issues have started to develop with one of them...developing in the following order:
1. Hard starting when hot. Starts easily cold. Either starter will crank slowly, as if combating crazy pressures in cylinder, or it will crank rapidly....pitpitpitpitpitpitpit...but not turn over unless bump started.
2. Loss of top-end power.
3. Overheating in high-stress situations(up the mountain).
Cleaned the carbs a number of times now. Doing some reading here(you guys are awesome) i learned that these(with the partial exception of the overheating) are all signs of running too rich. Throw in the high alititude and things were making sense...I reset the float heights, and have even turned the pilot screws out to just .75 turns. The bike is running better, but not quite as well as the other two bikes.
One interesting thing that I dismissed early on was a kind of grimey, sandy sludge on the slide valves of the carbs the first time i cleaned them(like a smoother, more putty-like, less abrasive version of grinding paste). I wiped it off and didn't think too much about it. Thing is, i recently discovered this grime will re-appear even after just one 300k ride. Also my diaphragms are always somewhat wet, making me suspicious that petrol is spitting back up to the diaphragms/slides, degrading them, and the sandy paste i'm observing is actually the plastic of the slides having been eroded and ground by the petrol/grinding against the carb assembly. I looked online to see if it's normal for the diaphragms to be wet but can't find any answers.
Are wet diaphragms normal? Where is this sludge on the slides coming from? Thanks a ton in advance! Cheers!
-Ryan
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sorry, i also should have mentioned...the 'wetness' is oily...not like engine oil, but like engine oil and petrol have combined and given me this thin, non evaporitive liquid.
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How do the plugs look? Any smoke out the exhaust? Have you checked the valve adjustment?
I think I would want to do a compression check.
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Plugs are all rich-ish looking...not fouled, but definitely not the happy tan color i hear so much about.(still have yet to see one with my own eyes!)
yup. Smoke is there, but only when the bike is cold. It's a black smoke that I suspect is from running too rich. The other bikes do the same thing.
I bought a compression tester a while back and it wouldn't fit the bike. Tried welding an old spark thread to the adapter and just made a mess...was able to rig up a pen glued into an old spark sleeve gasket that fit pretty snugly, and tested the compression by 'feel'. All cylinders 'feel' strong but of course i realize that doesn't inspire too much confidence.(working out of a small village in the mountains in lesotho...can hardly work with the tools we'd like to)
So...to Valve clearances...glad you mentioned that! I was so locked into the carbs that I wasn't thinking about this. We adjusted the valves shortly after we started having problems, and when double(and triple...and quadruple...) checking the heights after we set them we almost always figured out that something had changed! We were following the manual's procedure at first....but then later decided the heights were most consistent when measuring at 180 degrees to the cam's "elbow". Was too dumb to realize it then but now i'm thinking...maybe the cams are worn, giving us different clearances at different rotations(we were always measuring away from the elbow of course).
Which would mean that the measurements are so close...when the metal is cold the valves are happy...but hot and expanded the behavior changes drastically! Makes sense with regards to the symptoms of the bike!
So now my next experiment i think will be to over-set the valve clearances. What are the limits for this? How much should I go over from the manual's specs(for intake i think .15 and exhaust .2mm)
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Improper valve clearances wouldn't really have that much effect on how rich the bike is running. Just a few questions to help us to help you out:
Year/Model of bike and CC
Main and Pilot jet size
Turns out on the mixture screws
Jetted, stock?
Aftermarket pipe?
Float height on carbs?
Emulsion tubes worn in the carbs(could be it as it would dump alot of extra fuel on the slides)
Needle position or shims? (A really rich needle will also dump fuel unnecessarily)
If you don't know all the info just try and do the best you can. A big hint would be if the bike has been Jetted with an aftermarket pipe. Perhaps the previous owned did a really crappy job jetting it(we see this alot) and now it's super rich. Usually when there is alot of fuel dumping into the slides it can be these things:
1. Mainjet way too rich
2. Mainjets actually worked themselves loose and it's just a big ass hole with the emulsion tube the only thing holding the fuel back(saw this once but usually only one carb will be bad not all of them)
3. Needle extremly rich will also dump fuel
4. Float height set too low which will flood the carbs
5. Pilots way too rich or mixture screws turn out too many turns will make the low end rich
6. Pilots working themselves loose
7. Emulsion tube is ovaled and worn dumping extra fuel in there when the slide comes up(can be sort of temporarily fixed sort of by lowering the needle a notch or two)
8. Air filter dirty and clogged
9. Emulsion tubes loose or O-rings dead
The best advice I can give you is take one of the outside floatbowls off so you don't have to pull the entire carb bank off and take a look in there. Unscrew CAREFULLY the mainjet and pilot jets and write down the size. They should be marked with a number, mainjet sizes for a Bandit 1200 will be like 100, 110, etc in steps of 2.5. Pilot jet sizes would be around the 15, 17.5, etc. Dynojet mainjet sizes will be in steps of 2. Mikuni jets are in steps of 2.5.
If you have a Dynojet kit in there, they use crazy ass rich float height settings to achieve their jetting but their Mainjets are smaller. If you have a Bandit 1200 the Dynojet kits suck for some reason on this bike. Since the Dynojet mainjets are actually smaller than stock sometimes people after maxing out on the Dynojet kits will order Mikuni jets instead which really make it rich, it just turns the jetting into a cluster phuck. Anyway don't sweat it even if it's all messed up depending on the model we can suggest the proper jets to try and sort it all out.
For example I have a Generation 2 2005 Bandit 1200 with a Holeshot jet kit installed:
Mainjet: 112.5
Pilotjet: 15
Mixture screws 3.75 turns out from lightly seated
Float height: 13mm
1.5" extra hole in the top airbox lid
Stock filter
5 shims on the needle(or if you have an adjustable tell us how many notches from top)
Muzzy Slip on with mid-pipe
If you get this sort of info it would really be helpfull. For example one guy had some winner install a jetkit on a Stock exhaust and intake.(WTF?) Needless to say it was rich as hell, you can't just add fuel or air without adjusting either to keep an apropriate ratio. See what you can come up with and we can help you more. Just be REALLY CAREFULL with those jets, they are soft brass so don't go jihad screwing them in and out, nice and snug is fine.
If you have the pilots out only 3/4 of a turn you either are compensating for a super rich mainjet as you said the top end is crappy or the emulsion tube has ovaled and is dumping extra fuel in there. Or your float height is crazy low or your pilots have been changed out for super rich ones. Did you take a look at the emulsion tube to see if the brass is worn? The emulsion tube is the hex nut tube that the mainjet screws into. You want to check to see if the top of the emulsion tube where the needle seats is perfectly round and not ovaled. Here is a pic of an ovaled emulsion tube needle seat:
(http://www.fj1200.info/IMAGENES/Carbs/emuwr3.jpg)
Is it all the carbs that are rich? Which would suggest the settings are off. Do you have a stock or a K&N filter? If it's a stock filter the bike would run alot better with a K&N if it really was that rich, however the real solution is to jet it to what your normal setup is.
From just your symptoms with zero information I would guess the mainjet is way too rich. Once you have the mainjet sizes, etc we'll be able to help you more. These bikes are almost stupidly easy to tune so if the previous owner phucked it up don't worry about it, we can probably get you set up quickly. Black smoke and running better when cold than hot is a sure sign of richness. Valves only affect the size of the fuel/air charge not the ratio of fuel to air as the wet slides will attest to is way too rich. Is your needle adjustable? If so lean it out one notch for fun by moving the C-clip UP one notch and see if you suddenly get some more power when warmed up.
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Awesome, thanks rider!
bike is a '93-ish import(i suspect from japan) that i bought in south africa, reg papers say '93 and that service manual seems to be accurate so far, with the exception of some small electrical differences.
Before i dive into the carb details, all three of our bikes run rich, likely as a consequence of altitude. All of them have black, smokey exhaust cans but they are not drinking oil(well one of them is, but not much...and for old bikes i can't complain). They all improve when we go down to the lowlands, and i suspect they'll be great at sea level(which we are hoping to take them to the coast very soon). This bike, while running rich, isn't running INSANELY rich. It never fouls itself out. Even at the top end, i'll sit there with the throttle wide open and get nothing more...it doesn't sputter like it's fouled...it just stops giving like the slides aren't rising the needles out or something else is going wrong...it's not flooding itself out, really...so while the starting problem can be tied down to running too rich, I think something else is happening with regards to the top end.
Pmackie's noting of valve clearance sounds promising, actually...if a clearance is set too close, the bike valves are sealing up nicely when the bike is cold...then when the bike gets hot things expand and the valve doesn't seal...in the case of the intake valve maybe during compression the mixture shoots back into the carb, cutting into performance, causing overheating, soaked diaphragms, and MOST telling/promising is the erratic starting(when hot it never starts via electric...either super slow cranking or super-fast cranking...but never normal). The way it starts makes me think...sometimes the valves are sealed and the starter is struggling with the hot engine...turning slowly. Other times when it's hot enough maybe there IS a valve leak(or two) and the starter turns the engine super-quick but with the loss of compression still can't start the bike.
That being said, keeping things simple it makes plenty of sense just to say it is just flooding when it's hot, so i really want to get all the carb info to you ASAP. It will be a few days. Right now i can say:
Carbs: Twenty year-old bike, and the needles and jets look relatively new. Either it's been rejetted or parts have been replaced. Can't remember for sure all of the specs, but by my memory all of the jets were in the 90's size-wise. The butterfly valves have a 95 stamped on them. At one point i had the suspicion that the main jet needle was too long, as it extends a good centimeter into the emulsion tube with the slides raised completely. Is that normal? Needle clip is currently set at the highest position(leanest), and i'm suspicious that by actually lowering the clip(making it run more rich), the needle will come out of the emulsion tube more and give me the top end back. Is that possible? Float heights i'm certain are good at 14.6 plus or minus a little(i used the 45 degree angle trick to help make sure the little springs on the needles weren't compressed). Carbs have also recently been balanced by a professional. It did a lot to help the idle. He thought he had cured the bike but never got it hot enough i suppose and never saw the whacky behavior.
In the mean time, while we wait for my lazy ass to dig up the actual jet sizes:
1. Does my asessment of the valve clearance, esp. With regards to the starting, make sense? Is there an explanation for why running rich would make the engine turn over quickly and not catch?(trying to see if maybe i'm barking up the wrong tree with carbs).
2. If the main needle is too long, will it cut off the top end of the throttle? Will setting it a clip down(making it more rich, which i really don't want to do) restore some top end?
3. If I do decide to dig in and re-set valve clearance(which i don't think could be a bad idea), what is the maximum clearance i can give the valves, to help account for cam wear?
Thanks everyone! Cheers!
EDIT: forgot to mention, something that might make you all cringe a little is that the air filters are all stock, and warped to hell. I've tried duct-taping the holes with no noticeable difference in performance. The 'filter' is literally just a spongy black foam that sits in the air box. Currently, the bike with the problems has the nicest of the air boxes, actually. It's probably doing its job pretty decently.(better than the other two bikes which aren't having troubles).
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I'm assuming by your jet sizes etc, Your talking about a Bandit 250 or 400 or correct? Don't worry about the needles extending into the emulsion too far thats normal. Since you're lucky enough to have adjustable needles you don't have to worry, even with it on the lowest(richest) setting it's not going to come out of the emulsion tube or anything. As you go up in altitude you have to reduce the mainjet size. The needle only affects the mid-range and 1/4 to 3/4 throttle inputs. Top end and over 3/4 throttle is all mainjet. If you want to see definitively what the top end is doing is find a place you can really hammer the throttle without going to jail get up to third gear and accelerate full throttle to near redline then hit the kill switch just before redline and coast to a stop. Be careful as the plugs will be hot but try and take one of the outside plugs out of there. The top 2/3 of the centre electrode should be burned clean and there should be a nice light to dark grey ring around the base where the ground strap is welded to and deep in the plug near the bottom of the electrode should be a light grey tinge to it. If the base ring is black or has sooty deposits on it you are too rich.
You can also use this to guage your cruise and needle settings as well.
For example to test to see if you are rich down low, ride around with light throttle inputs going through the gears gingerly and just sort of cruise around at less than 4000 rpm and pull the plugs. Same thing here your base ring should be a light to dark grey and there may be a little more deposits on the centre electrode and the tips of the electrodes closest to the ground strap should be a dark grey max. If you see sooty black tips with a sooty black base ring and some dark colouring on the tips of the ground strap than your cruise which is handled by your pilots are probably too rich. If you see some dark streaks on your centre electrodes is also a sign of the needle at cruise may be a bit rich as they all sort of overlap a bit, however since you have it on the leanest setting I kind of doubt it.
To test the mid-range its the same sort of deal but in the case you want to do a few passes with 1/2 throttle from say 4000 rpm to 7000 rpm or whatever the mid-range is based on your redline. So the best way to do this is cruise until 4000 rpm in 3rd or 4th gear then peg the throttle at 1/2 or so up to 7000 and go back down and do this a couple of times. You're basically artificially doing a few passes in the mid-range. At the last pass hit the kill switch at 7000 rpm and coast to a stop. Check the plugs, needle position with show up as streaks on the centre electrode as well a the base ring. Base ring should be a full turn of light to dark grey with either a clean centre electrode or some light to dark grey streaks on the centre electrode. If the base ring is sooty and black or there are black streaks on the centre electrode then the needle is too rich. In fact I would be worried since your needle is so lean(could be previous owner is compensating for a crazy ass rich mainjet) I would doubt that the mid-range would be rich, it may actually be very lean.
The best way to sort everything out is to give us a little more info:
For example pick one bike that is the least screwy so it will be easier to get running right then just do the same on the others. So on this bike:
Does it have an aftermarket exhaust or stock? An aftermarket exhaust will flow alot more than the stock and will need a richer mixture.
What CC's/Model is this bike? There are 2 types for example of the 250cc, one has Variable valves which may be the reason the valves are wacky, I don't know how the variable ones are adjusted but maybe there is a special procedure?
Try and get definitive jet sizes for Main AND pilot. Generally the needle should be on the centre or neutral position for testing. The fact that it's on the leanest which is extremely unusual leads me to believe its a jet job gone bad and the guy before you was compensatinig for a rich main or pilot jet. Which would make is screwy, ie rich down low and lean at mid, then rich up top for example.
Is the air filter stock or a K&N? Is the filter dirty? Has the K&N been cleaned and re-oiled properly? If you put too much oil on a K&N filter it will totally screw with the jetting(make it rich)
Try and give us the model and CC as there are Bandits from 250 to 1200 CC so we need the model so I can scare up the manual and look up what jets should or should not be in there. From the jet sizes at least you probably have Mikuni jets in there which helps alot for sorting it out. Since jets are only a few bucks each it's not super expensive to jet for your altitude.
If you want for fun to see if you get a little more omph put the needle down one notch richer and see if the transition area in the mid-range is stronger, ignore any other richness overlap for now. You can always set them back if it doesn't go well but that will give you an idea if the mid-range is artificially lean. Even if you are super rich, if the mid-range is improved then you definately know that there is some compensation going on there.
As far as the valves go, I had a similar problem with a GS750EF, what the problem was is the previous owner let it sit too long and some of the valve springs lost their strength so the bike wasn't sealing the cylinders properly when hot. If you do a leak down test when warm this will show up as lost compression or slow leaking compression. All I did was buy new springs, pop them in re-lap the valves and the bike drove like new. Since your bikes are 20 years old it's possible the valve springs are tired and when heated up are losing some strength(heat makes metal softer) and not sealing the valves properly. It's not that hard of a job to do, just be sure to buy enough beer as you don't want to run out mid way! :grin:
If you want to be lazy, just skip the lapping process, I did it in winter so I didn't care how long it took. Try replacing the valve springs on one of the bikes and see what happens it's not super expensive and after 20 years they are probably due anyway so it's not like your throwing money away.
Although on the flip side if the bike is super rich it will have problems starting when hot. For example on ANY bike if the bike is warm and you pull the choke to full it will be hell to get the thing to fire up if at all. It will literally be drowning the engine. When the engine is cold it needs the dump of fuel to get started until the engine is hot enough to use a lean enough mixture. A leakdown or compression test when warm will tell you one way or the other. Thats why I suggest fixing the least phucked up bike and use that as a benchmark for fixing the others. If you have one that is jetted correctly with a new air filter with properly sealing valves your gold just reproduce and fine tune the others and your set.
EDIT: If the air filters are warped and phucked up it may be worth it to go and buy OEM stock airfilters for all the bikes just so you can eliminate that possibility.(God knows when they were last changed) If the previous owner totally butchered the airboxes or whatever you may have to re-jet to use K&N pods just to sort out the insanity. At least you'll get some extra power. Do all the bikes have aftermarket exhausts? And what the hell are they?(model) :grin:
Fill in the blanks:
I have a 1993 Bandit _______:
A. 250
B. 250 VVT
C. 400
D. 600
E. 1200
F. I have a Kawasaki you retard!
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Opps forgot the starter. There was a guy here who had a wonky starter that when hot wouldn't have enough power to turn the engine over. When it doesn't turn over you say its making a grinding starter clutch slipping noise? or just chugging? I say we try fixing one thing at a time before we start tackling all the problems at once and problem number one is having non-valve seal-age and wonky jetting setups. I would do the cheap stuff first, go and buy OEM filters to replace the bent and warped ones for all the bikes that would probably help the richness immediately because God knows when those filters have been changed. Who knows maybe the guy never changed them and the bike is rich as hell because the filters are clogged.
Next choose the least wonky bike to get running right so you can use it as a bench mark for the others this will save time and energy down the road. Do those simple things first and it will be alot easier for you. If the bike you choose you feel the valves are weird it might be worth the money to get a compression test when the bike gets wonky and explain it to the mechanic so he can do a leak down/compression test.
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Super response. Thanks so much for taking the time to make it clear.
Sorry about the confusion the bikes are '93 bandit 400s. I think the one with the issues is a japanese import.
Right now, for the other two bikes i'm of the opinion--if it aint broke, don't fix it--. Each bike is quite unique with regards to mods, and carbs. One of them is a vv(the one with problems is not), and each probably would require some unique changes with the carbs.
Truth is we will only be riding the bikes for a few more months, mostly down at sea level, and then ditching them in south africa to go back home to the U.S. So it's not worth our time/money to invest 'too' much. That being said, we want the bikes to run well and understand that there is no magic button to press to get things sorted out on this bike that's giving us problems. In the end...the other two bikes are running well...not perfect, but well, and I'd rather not risk making anything worse. If it aint broke, don't fix it, kind of thing.
As for special mods to this bike...nearly everything is perfectly factory with the exception of some wiring. The exhaust can has a big-old ding(EDIT: Huge-ass dent going along the whole length of the can) on the side facing the bike...like it was dropped and then rotated and re-set for aesthetic purposes. How would this affect the tuning of the bike?
Went for a run today on it with the needles raised(clips dropped to be clear) one clip. More grumbly and pingy through the exhaust on the whole range of revs but initially i thought it had more top end power...i think it was just that the bike stayed cooler for longer, though. When i got to city it was nearly impossible to keep the bike alive at low revs as the flooding got bad. Anyways...the leanest setting on the clip is where it will stay for now.
I'm suspecting main jet more and more the more you explain to me. May have a chance to look at it soon. How do you get that sucker out?
I like your idea of valve springs...is that a generic part or do I have to buy OEM? Thing is these bikes are gray imports in South Africa, meaning Suzuki dealerships can't even order parts for them. We also want to get going on a trip soon. When cold, the springs SEEM very strong, but i don't know how much that behavior changes with heat. Perhaps i can measure them and compare to manual spec?
Starter is not grinding...just sometimes trying to chug along but not getting it done, while at other times racing quickly. I don't think the starter clutch is slipping or anything. Also realized today that pulling the enrichening lever when it was turning quickly but not starting made it turn even more quickly...definitely thinking valves as a suspect on that end.
So...is allowing some extra valve clearance unadviseable?? I'd really like to try it, and then if that doesn't help invest in some springs.
Thanks so much for your help! Currently on my list of things to do is A. Check main jets for wear and B. Give extra clearance on the valves. Cheers!
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Changing the mainjets is not as hard as it sounds. In fact if you loosen the throttle and choke cables usually you can tilt or slide it enough to get in there to change them out. Of course its easier when you take out the bank of carbs. Look for the mainjet that will be screwed into a long hexagonal bolt which is the emulsion tube. Here is a pic of my Bandit 1200 carbs which is slightly different but the general layout should be the similar:
(http://www.portablepct.com/fastlarry/2001b12carbs.jpg)
As you can see the mainjet is screwed into the emulsion tube. The thing called the "Mid-Jet" is the starter circuit jet.
Here is a microfiche for a 93 Bandit 400 carb bank(American model anyway):
http://www.bikebandit.com/1993-suzuki-gsf400p-bandit/o/m6137#sch246848
Its kind of a crap picture but #30 in the microfiche is the mainjet which says 105 but I'll double check that with the downloadable manual in the downloads section. If you have a Mainjet that is LOWER than stock. It's quite possible someone popped in a Dynojet kit on a stock exhaust and mid-pipe which kind of defeats the whole purpose which would make the jetting wonky. The best info you can get is to take off the float bowl of one of the outside carbs and check what's in there for sure. When I get back from work I'll be able to look it up at least what should be in there stock.
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1. Does my asessment of the valve clearance, esp. With regards to the starting, make sense? Is there an explanation for why running rich would make the engine turn over quickly and not catch?(trying to see if maybe i'm barking up the wrong tree with carbs).
Hey Rmack87
123 has given you a lot of jetting info, so I'll stay away from that area.
It is NOT likely that that the valve clearances are allowing significantly more pressure when cold than when warm, but I am concerned that based on your description, that you may have two issues:
1. The bike sounds rich. This would cause it to run better when cold, and worse when hot.
2. I am concerned that 1 or more cylinders are low on compression. Once warmed up, the combination of low compression and the rich jetting causes a fall off in performance.
I thnk you should be doing a proper compression test, both dry and wet, and if at all possible, a leak down test.
Of couse, you should make sure that the valves are properly adjusted first. You CAN set the valves to the Loose end of the spec, but don't get too carried away.
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I agree with PMackie a compression test would really give you an idea on how well the valves are sealing the cylinders. Even if the compression is fine(hopefully) at least it would eliminate that as a source of a problem. If you want to test the cylinders without taking the timing cover off to turn the crank you can put the bike on the centre stand and put it in top gear, then you can just rotate the back tire to turn the engine.
Another good test to see if the valves are sealing well is measure the compression at the top and hold it there. If you see the PSI's slowly die off like a leaking tire then you know that cylinder is not holding its compression and the valves are not sealing well. Some die off may occur just from ring leak or the compression guage not sealing in the sparkplug hole etc. but if it's going down fast then you know those valves could probably use some new springs and a lapping. It made my GS750EF run like new.
Test if possible cold then hot. We can work on the wonky jetting together as it will be easier than redoing all the valve springs etc. Like I said invest the $20 a piece and get new filters to replace the demented old ones. You never know it may completely fix the problem with the wonky jetting. I've seen some pretty rough airfilters in my time from laziness or lack of knowledge that they need to be changed out so a quick $20 is a good place to start before outlaying more money. A new filter may even fix the horrid richness who knows.
Even if it's jetted crazily a set of 4 mainjets is like $12 so you don't have to spend a crazy amount of money to get them running well which translates into more cash for you when you sell them. The $12 invested in jets may turn into $200 come selling time.
I believe you said you had three bikes? Even if one needs alot of work just sell it with the pair as a parts bike and you don't have to spend a penny on it that why I said to concentrate on the least phucked up bikes first which will give you confidence to tackle the demented ones and the least amount of money as well. Once you get the jet sizes on the least demented bike we can start to tune it a little better than all you have to do is replicate the results with the other two.
You said that when you put the needle one notch richer you seemed to get a little more power until the bike fully warmed up which tells me that the needle is set way too lean and the reason it's so lean is to compensate for either a rich mainjet or a rich pilot jet. If I get the numbers I can compare against what is stock and we can see which is the problem area. It could be that some fool went up on the pilots to try to improve the cruise range instead of giving it just another notch richer on the needle or he read something on the internet and like the broken telephone game got it wrong. If the pilots are only .75 turns out I'd say something is definitely rich. I believe the Bandit 400 needs them about 1 1/2 to 2 1/2 turns out, if it only needs .75 to keep it from dying that could be your problem there.
I did find the stock jet sizes however for you(American model):
Mainjet: 100
Pilot jet: 32.5
Since you have stock exhausts on there any jets other than those the bikes have been screwed with. I've been sort of half assed searching around and I've seen jetting done with K&N pods with like the mainjet at the 127.5 range and the pilots as high as 37.5 so if the previous owner just gets these magical numbers in his head not realizing you need an aftermarket exhaust system with pods and pops those jets in......Since some of the bikes airboxes have also been butchered I'd say someone was screwing around.
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Ok I got some more info for you. You can download a clymer guide for your bike here:
http://www.carlsalter.com/suzuki-service-manuals.asp
Chances are you have the Euro/Canadian/Asian model so you probably have the BST33 mm carbs not the American BST32's with the plugged up mixture screws and slightly neutered EPA jetting.
So to save you some time here are the stock settings(Anything other than the States):
Mainjet: 102.5
Pilotjet: 32.5
Mixture screws: 1 1/2 turns out from stock
Now for your bike there are two models the American and the rest of the world. It's possible some guy was reading something on the American model which needs more jet to come up to Euro/Canadian standards. If you are .75 turns out from stock I can almost guarantee you your pilots are at least one size up at 35. If not that the mainjet is larger than 102.5 so you need .75 turns out just to survive. The previous owner maybe read something on an American board to try and de-neuter the bike but is using settings for a slightly different carburetor. Who knows? Get those Jet numbers! :grin:
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great. Thanks guys. How do I remove the needle seat to check for wear?
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Well the microfiche sucks but there should be a hexagon stalk that the mainjet screws into. That is the emulsion tube just use a 8mm wrench and unscrew. Inspect the O-Ring as well that can be a source of leakage. However with the amount of fuel you have going in there I doubt its just an ovaled needle seat but it doesn't hurt to check.
EDIT: Just taking a side view of the CARB in the clymer manual it looks like the emulsion tubes are press fitted, if so then don't even bother checking the needle seat as you need to take the carb totally apart and tap out the emulsion tubes. Put it this way if you unscrew the mainjet and there is just a stalk there with no way to unscrew what the mainjet is screwed into then forget it. To be honest with the amount of fuel going in there I doubt a slightly ovaled needle seat would do that. What a ovaled needle seat does is just makes the mixture a little screwy(rich on the needle mostly) which can be fixed temporarily by leaning out the needle. IF your emulsion tubes are press fitted, basically non serviceable, you would litterally have to take the carbs entirely apart and get a punch to punch out the emulsion tube. Not worth it. If you still want to check you can take the tops off the carb and remove the slide and look down in the throat of the carb, you'll see the seat where the needle sits through the top of the carb, just have a quick check. Getting the Jet number is much more important. Just take an outside carb floatbowl off while the carbs are on the bike.
Considering your probably LEAN on the needle not rich, I would highly doubt the needle seat is the culprit, not with that much fuel in there.
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The tubes press out opposite the main jet. You don't need a punch just loosen the main jet a couple turns and push it with thumb. You do have to pretty much take the carburetor completely apart though.
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Yeah thats what I figured, a bit of a bummer. The good thing about my Bandit 1200 is you can practically do everything by just taking the float bowl off. I know the Bandit 400 is on the lower scale of bikes so maybe they cut a few corners but how much more dollars per bike is it to get slightly updated carbs? Like what? 10 bucks a carb x 4 over thousands of bikes? I'd be willing to pay an extra $500 over the price of my Bandit if it came standard with some nice flatslides on my 1200. Oh well. What I suggested is just take the slide out and take a look from the top, from the symptoms your describing though I'd say jetting is the problem but it doesn't hurt to look. Its good you can push them out with your thumb though I was going to reply saying you GENTLY tap with a punch but you beat me to it.
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alright, here's the info i got from taking apart the carbs:
Needle: 5DH15
Main Jet:96
Pilot Jet: 32.5
Condition of valve seats: Worn to various degrees. Can take pictures if you need them.
This is kinda disappoiting, because the jet sizes sound pretty close to factory. Let's talk gaskets...the o-ring for the floats seems a little funky in some for some of them. Like it's warped and the petrol has degraded them a bit. They still fit snugly, however. What are the odds that these o-rings could be causing me to run so rich?
Also...the fuel petcock has been known to suddenly release fuel as if it is in the 'prime' position, even if it's on. I've ridden the bike on 'prime' versus 'on' and seen no noticeable change in results, so the floats are definitely doing their job...BUT, i noticed today for the first time that the vacuum hose had a strong smell of petrol and was even a little wet today where it plugs into the diaphragm of the petcock. Could it be that a bad fuel petcock is delivering fuel through the vacuum hose, making my bike feel so rich? Would just one cylinder make me feel like the bike is rich all around?(on the 400 the vacuum hose is plugged into the carb boot of the 1 cylinder) Unfortunately you can't really get to the diaphgragm in this petcock without desroying it. It only lets you get to the reserve/main valve assembly, then you can't dig any deeper to get the the diaphragm. As an experiment i'm going to block the hole of the carb vacuum intake, put the tank on prime, and go for a ride just to see if there is a chance it is the petcock. I'll let you know how things go. Cheers!
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Ok well heres the good and the bad:
Good:
Pilots are stock so your in luck
Needle is adjustable so your good there. The Dynojet needles have a more agresive taper so when fixed may actually have a bit more juice especially at mid-range.
You got all the info you need to fix it up the jetting for like $10
Stock OEM filters are usually cheap mine is $20.
Bad:
Mains are less then stock and in steps of 2 which means a Dynojet kit was installed which is just foolishness from the previous owner as it still has the stock exhaust so it's basically doing nothing but wasting fuel and LOSING power. Also the Dynojet kits are made for the AMERICAN bike which uses totally different carbs so no wonder it's phucked.
Petcock diaphram is leaking fuel on the bike you pulled the carbs for info. I believe number 1 cylinder is the vaccum line puller so check that cylinder to see if petrol is leaking into that carb. Most likely if it's leaking fuel on the "ON" position the petcock is pooched, unfortunately for the Bandit 400 you can't rebuild the petcock. They are about $90 new or half at a wreckers. Thats probably alot of the rich problem, the float needle valves aren't usually strong enough to hold back the flood of fuel. Temp fix, run around with 1/4 of tank of gas or less with the vacuum line plugged on the prime, real fix, get a new petcock.
He also butchered the stock air filters so replace $20 bucks each is a good start.
What I would do is go order some stock 102.5's, keep the nice adjustable needles, set the needle on the middle position to test. Since you have 3 of the bikes you can either exchange the petcock from one that works correctly or go buy either a new stock petcock or a fancy pingle valve. Since you'll be selling the bikes shortly it might be worth it to do the cheapest/easiest fixes first. If the bikes are all the same colour, just exchange tanks on one where the petcock works so you can get the tester bike running fine.
It's sounds like a cluster phuck but really its not. Don't worry since you have all the info you need, %90 is just buying 4 102.5 mikuni jets and a new stock air filter for a total cost of around $30. As a bonus you do have the nice adjustable needles from Dynojet so if everything is back to stock you may actually have a bit more throttle response than the an equivilent stocker especially in the mid-range. That petcock is a problem though, are all the bikes the same colour? If you can use a tank from one that the petcock actually works properly or even just stick it on there to test you should be good. To fix everything %100 is less than $150 but will translate into a few hundred extra in your pocket when you sell the bike especially if the bikes are running well. Because of the previous owners foolishness your probably losing 5-7 horsepower due to the silly dynojet install on a stock exhaust. Once everything is back more or less to stock and you have the petcock fixed you'll notice the bike has some more balls especially up top. If you want to experiment a bit you could order a set of 105's especially if the airbox has extra holes or is butchered but I would stick to stock for now just to see if you need more juice or not. If you want to be super thorough even order 100's in case 102.5's are too much with the Dynojet needles.
To simplify:
Easy/Cheap fix:
102.5 Mikuni Mainjets x 4 $10 Or maybe 100's if too rich with Dynojet needles
New OEM stock Filter $20
Needle at centre position at first, adjust as necessary
Swap tanks with one that the petcock works, see how much they are at a wrecker
Mixture screws 1 1/2 turns out from lightly seated
Harder/expensive fix:
Stick to Dynojet jets and order some 94's or 92's $20, or tune to what you have.
Buy a brand new OEM petcock $90
Mixture screws 3 turns out from lightly seated with the Dynojet jets
Skip the airbox entirely and go to K&N pods + 127.5 jets, maybe $150? More? Who knows?
Just a little info. Dynojet numbers don't translate to the Mikuni jets directly. They use a different measuring system. Dynojet uses the size of the hole in mm's and Mikuni uses flow of CC/min for their jets. So the 96 Dynojet is .96 of a mm hole. Mikuni's 102.5, is 102.5 cc of fuel per min, which I think is more accurate. The closest to Dynojet is Keihen jets but they are still off a couple of points.
It's usually a few points below for Mikuni so on my Dynojet jet conversion chart a 96 mainjet is only a 90 Mikuni jet. However how Dynojet achieves better fueling is usually by lower the float height to a super rich level. For example on the Bandit 1200 they lower the fuel level from 13 mm to 11.5!! Holy richness Batman! and they have a more aggressive needle. So they take a different take on how and when the fueling takes place. Unfortunately for at least the Bandit 1200 their jet kits suck. They can be tuned but it's hell, one guy here got so fed up he actually sold the bike one month after buying it. If you have your float height at the recommended level, chances are you have holes in your jetting at certain RPM especially up top. As your equivalent jet is like 5 sizes leaner than stock so it's a bit weird thats why getting back to stock is such a good idea to clean up the insanity so you can really test it. Dynojet used to be the shit back in the 80's but it seems they kind of went by the wayside lately for some reason. I haven't seen any bike that can't be tuned by just ordering larger or smaller standard Mikuni or Keihen jets and maybe needle shims or an adjustment.
My guess is that the petcock died and the previous owner who obviously didn't know what he was doing was like "My bike is running crappy" so he went on line or had a friend who knew slightly more(or less!) to suggest he get a jet kit to fix it. Instead of just fixing the problem they moved it around a little and in the process made it even more phucked up. We see this sort of stuff alot. The problem with your bike at lower rpm the bike is going to be super super rich which explains why you have the needle on the leanest setting and the mixture screws at .75 turns out because thats the only thing holding back the niagara falls of the fuel that going into the carbs with the dead petcock. At higher RPM when the jetting evens out your are now running super lean because your settings are at such a lean level which probably explains the lethargic top end.
Theoretically once the petcock gets fixed or changed with one that works from the other bikes you can tune the Dynojet kit if you want to keep it. I'll find the .pdf instructions for you. At least you could probably get it running "ok". I did take a quick look and you are using the leanest jet out of the kit so it may be ok if you want to spend the time tuning it. Let me see what I can find.
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Ok here is the Dynojet kit .pdf:
http://www.dynojet.com/pdf/3134.pdf
The problem is it's for American models so they want you to drill spacers, etc and kill the EPA shit that you don't have. But just leave everything and fix the petcock first and move the needle to the mid position. The good thing is it's using the stock float height so you're good there but if you look at the instructions there is a huge ass "U.S. MODELS ONLY". So even if I was geographically challenged the previous owner could at least ask himself...Is South Africa even on the same hemi-sphere as N. America? Should I be buying this kit? I'm just trying to help get it so at least the bike is drivable while the Mikuni jets come in for you which is the real fix, after fixing the petcock first of course.
On the Dynojet instructions they want you to put the mixture screws to 3 turns out which is alot more than the 1 1/2 turns out recommended by stock(probably why the don't touch the float height) so if you fixed the petcock you may have to turn them to that sort of a level so you can function with the super lean mainjet. I don't know man the dynojet kits are weird which is why I suggest going back to near or at stock, especially since your using a jet kit for a totally different carb. It's up to you.
If you want to use the Dynojet stuff in there here is the starting position:
Needle: Middle position
Mixture screws: 3 turns from lightly seated.
Mainjets: 096 Dynojet jets
Pilots: stock
Float height: stock
Remember though these settings are for the US model so you may have to adjust up or down. Good luck!
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Wow, solid mystery solving skills, rider. Thanks! The previous owner was indeed american and bought the bikes for himself and some friends to travel around SA during the world cup...he probably bought the U.S. Dynojet kit for cost's sake(the cost of spares in SA is outrageous!), then didn't realize that the bike was worse off as his friends were probably the ones riding it, or maybe he chocked it up to something different, who knows!
Went to bloemfontein(300K round trip) today to try to do some spares hunting with the tank petcock on prime and the vacuum hose plugged up. Ran ever so slightly better. Instead of needing to wait thirty minutes to cool before electric start would work, I only had to wait maybe ten minutes! Which is indeed promising...maybe if I can find a way to get these settings right, the bike will start when truly hot!
The bad news was I could neither find the jets nor the petcock. The suzuki dealership would have to order which could take up to three weeks, which we're hoping to be on the road for our trip by then. Our plan, then, is to order the parts through Durban, which is a slightly bigger and more bike-oriented city...hopefully they can find a secondhander for us and get the jets locally.
I will try the settings reccomended above with one of the gas tanks and petcock from another bike. I'm nervous, though, as it's hard to believe it won't be running waaaaay too rich. It's worth a shot, though! Heading back up to our site in the mountains today and will hopefully have a chance to play around with the needle tomorrow. Cheers!
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Whoops...asked a question about jetting sizes of mikuni vs. Dynojet and then realized you did a fine job answering it two posts up!
Thanks!
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Don't sweat it too much that you have a Dynojet kit in there. Even thought the previous owner phucked up and put a kit for another carb in there. The settings and intake apature of the Carbs are similar enough you can probably get it to work with some fiddling. The big issue is getting so that the carbs aren't being dumped a shitload of fuel into them, screwing up the jetting. Does one of the other bikes petcock work? Try the lazyman's way for now to test by just exchanging the tanks even if they are not the same colour and try the standard settings for the Dynojet kit and see what happens. That should save you a lot of time. You never know you could probably get it running pretty close to perfect you sound like you know what you are doing. The bike doesn't really care HOW it gets the fueling as long as it's correct. If you stuck a WWII German sidecar Zundapp Bing carburator on there and got it to work somehow, the bike wouldn't care as long as the fuel is metered correctly. I would imagine that once the petcock works and the standard setting on the Dynojet kit are in there, you may be slightly lean unless your at a higher altitude.
Since plugging up/clamping the the vaccuum hose and running on prime make it work better(I bet you its lean now at least when running). I would try a notch down at least on the needles and it will probably run even better. Also I would maybe try to go to the stock 1 1/2 turns out of the mixture screws as well. If you keep the tank less than half full it won't put as much pressure on those teeny float valves. Since the starting issue is better, I would guess when you stop and the fuel isn't being used it's piling up in there making the carbs so rich it will not start hot. As soon as you are running you're burning off the excess so the fueling gets better. If you exhange the tank temporarily or get a new petcock try the standard settings for the Dynojet kit which is needle at middle notch and 3 turns out or just work up from the 1 1/2 turns stock. Go for a high speed highway run as I bet your cylinders are probably black inside to clean it up, and come back home and pull the plugs and adjust as necessary.
The thing is look at it this way. My tank which is 20 litres is roughly 1kg/l or 2.2 pounds for every litre of fuel(gas is actually a little lighter) so a full tank without the petcock to regulate it is pushing down with a force of 44 pounds. I don't know of any motorcycle float valve in the world that can hold back that amount of fuel. Even only 10 litres is still 22 pounds of fuel trying to be stopped by those dinky little needle valves. It just can't handle it. How the petcock works is that vacuum is applied to a spring loaded diaphram and pulls on the diaphram depending on the engine RPM. So when you are idling it's just letting a trickle of fuel through so you aren't flooding the hell out of the carbs, at high rpm it pulls the diaphram more so that a whole bunch of fuel is allowed into the floats. With the diaphram not working and stuck open, you are basically feeding the carbs enough fuel at full throttle even though you may be at idle! Or even worse Stopped! It also prematurely wears the needle valve tips as they are being ground hard into their seats by all that fuel pressure.
No wonder it has problems starting when hot with those little dinky fuel valves are trying to hold back a full throttles worth of fuel when only sitting at idle or stopped. I would imagine if you parked the bike long enough I bet you the fuel would eventually leak into the crank case and out the airbox. The fuel valves are not designed for that pressure. However when you are running there is less pressure on the fuel valves as some of the fuel is being used to burn in the combustion chamber. Needless to say the petcock is number 1, then try to fix with what you have is number 2, and if you want to go to stock jetting ordering the jets would be number 3.
Unfortunatly from just researching this problem for you it seems that shitty petcocks is sort of characteristic of this bike. There are literally hundreds of posts out there on other forums. I guess Suzuki cut some corners on this bike to sell it cheaper. I guess that's why people spring for the fancy pingle valves. But since you will only be riding the bike for less than a year just get a wrecker petcock. If you get the bikes running well you can sell them for more money, so say a used petcock for $50 may translate into $150 bucks back when you sell it or maybe more because no one is going to buy a bike they have to fix unless it's like half off.
Put it this way:
Sell bikes as is, $1000 maybe and hard to sell, if at all most people won't touch a bike with carb/fueling issues, even if its easy to fix. Especially since these bikes are considered "beginner" bikes, chances are you are selling to a kid who wouldn't know how to fix it even if you told him how to do it. May have to sell less for parts only.
Sell bikes with $100 new petcock and jetting fix(free or $10), $2000 easy to sell, Maybe more if they're extra clean. Keep the receipts of any new parts as proof, Also a good selling feature, proves you took care of the bike. Might be worth a new petcock just to have it run awsome for a year and from an economic standpoint.
The previous owner instead of buying a Dynojet kit for $150 could have bought an aftermarket Can and slip on for $150, and $10 worth of jets and could have done it properly and gained an extra 5 HP instead of losing 5 HP. Oh well. With a little patience at the minimum you should it at least get it running as good as stock, probably better.
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Im a bit late to this so fogive me if ive missed something but IF its got a Dynojet kit in it will run smaller mains as the Dynojet jets flow more fuel than Mikuni's jets, also the needles are finer and if they do not clear the needle jet/emulsion tube when at full throttle this will also allow more fuel out of the needle jet. Fitting stock mains may or maynot richen/lean the mixture.
There is info in the 400 jetting section regarding the differences between the makes.
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The entire weight of the fuel in the tank isn't pushing in the fuel line, only the small stream directly above the petcock. I've left mine in prime settings for weeks and never had any overflow. The float valves hold fine. In many an old car that has a fuel pump supplying from the tank the only thing stopping the flow are the float valves.
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True, but there is the entire weight of the fuel trying to push through that line either way it's alot more than should be pushing on those needle valves. Plus with all that fuel trying to empty into that relatively small fuel line the pressure of the fuel actually goes up not down. However that is great at full throttle when you need a lot of fuel and fast and keeps a nice constant pressure when rolling on and off the throttle hard which is what you need. But not so good when your stopped. Hence the petcock vacuum valve, they wouldn't have bothered if it wasn't necessary. If the needle valves are brand new or in good shape they will hold it off for a while however on a 20 year old bike it just can't handle it. They will fail eventually though. Although with less fuel in the tank it gets easier and easier for the needle valves to hold off the fuel so a full tank may leak but it may be fine with half a tank or 1/4 of a tank.
Also in a car when it is running is only when the fuel pump is activated to push the fuel up from the gas tank at the rear uphill to on top of the engine at the carb area. When the engine is shut off so is the fuel pump, the gas will pool back down under gravity back to the fuel tank.
With Dynojet, their jets don't flow more fuel they just have a different take of jetting of a bike. What Dynojet does is makes the overall jetting richer by usually increasing the pilot mixture and/or float height and having a super aggressive taper on their needles. The reason they have small mainjets is because the bike doesn't need it as the overall mixture is much richer than would normally be experienced stock.
For example on this bike they want you to turn the mixture screws out double what stock is and if you had the stock mainjets it would have been dripping with fuel so what they do is lower the mainjet and use the needle taper to meter the fuel instead of the pilot screws down low to compensate for the richness down low and a smaller mainjet up top so the bike isn't drowning with fuel. On other bikes like the Bandit 1200 they use a combo of mixture screws and a way lower fuel height to richen up the bottom. Typicially the Dynojet needles are slightly longer with a super small needle point at the end to get the fuel on quicker and faster but a little later in the rpm scale than the stock needle. There are advantages and disadvantages to this setup. The main advantages would be a smoother power delivery as well a theoretically better overall fueling, the disadvantage is worse fuel economy than would be acheived with a typical up on the mains type of jetting. With Dynojet it's all in the needle.
However with this sort of setup some bikes hate it alot. One being the GEN2 1200 Bandit, probably because the pilot jet is extremely small and can't provide enough fueling to compensate for the Dynojets smaller mainjet. They try to get around this by artificially lowering the float height to a super rich level but the carbs don't seem to like this very much and it usually makes the jetting wonky instead of good. This is really a symptom of emissions regulations than Dynojets fault. On older bikes they were fueled better overall as the motorcycle companies could concentrate on proper jetting rather than pleasing some politician. For example my Bandit 1200 stock has the same airbox as a Bandit 600 and the jets are actually SMALLER than the Bandit 400 made 15 years earlier. This is all to try to get past the emissions crap. Thats why the 1200 gets so much power by drilling a 1.5" hole in the airbox lid and upping the mains. Really that's how it should have come out of the factory but the emissions are measured at idle so they use a miniscule pilot jet at 15 which is less than half of the 400 which has 3 times less the displacement.
So what this means on the Dynojet kit where the pilots supply alot of the fueling is that the pilot jet doesn't have enough juice to supply the Dynojet's fueling philosophy so hence the wonky jetting on the Gen2 1200's. As emissions regulations get more and more strict the Dynojet kits will work less and less, unless they supply the appropriate pilots themselves which is probably what they are going to do or just concentrate on fuel injection modules or something.
On stock bikes they get around this buy having an artificially low pilot jet and having a normal sized mainjet with less air getting in there so it can work with the artifically low pilot jets. They are really hobbled out of the factory. They mainly use the mainjet to supply most of the fuel instead of relying on the pilots to contribute alot to the overall mix. The whole purpose is to "fool" the emissions testers so down low they are artificially lean. This has some advantages and disadvantages as well. The advantage is a leaner cruise mixture which will mean better fuel economy, but the jetting will be very cold blooded until fully warm and there will be a bit soft below 1/4 throttle response. If you look at my sig at the bottom I have a pretty rich mainjet compared to the 100 stock, because thats what I need to function, the pilots are too small to contribute enough to let the needle and pilots do most of the work so you need to shim the needle alot to bring on the fuel from the mainjet sooner to increase the power and compensate for the dinky pilots. Even with my pilots at 4 turns out it still is a bit lean although it is only 3 degrees celcius so at summer temps it should be fine.
Really the Dynojet philosophy is the best way to go with less abrupt changes from different jetting circuits, but as the bikes came under harsher and harsher restrictions it's getting harder and harder to get them to work correctly. Thats why back in the 80's and 90's Dynojet kits were "the kit to get" because the bikes were jetted better overall not having to fool any emissions bullshit.
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Ive read a little more but SO MUCH to read and about other bikes than the B4.
The needles listed are wrong all B4 needles are 5EZ im sure the gsxr400 gk73a has the ones you list 5DH and also has 96 mains.
I would say its got gk73a carbs on, can you post the code on the side of the carbs?
Also are you sure the top end issue is not the jap speed restriction kicking in.
Is the airbox completely standard and what grade plugs have you got in.
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Even if the GSXR400 Carbs are on there a Dynojet kit has still been installed(at least at one point) as Mikuni jets are in steps of 2.5. Dynojets are in steps of 2
Jet Needle: 5DH7 stock
The gsxr400 carbs have a 97.5 mainjet(one or two smaller than Bandit 400 depending on US or Euro/Asia)
and the same pilot jet at 1.5 turns out on the mixture screws.
Same float height
It could be that the previous owner installed a Dynojet kit was too rich because of the dead petcock and thought that he would put the stock needles back in there as they are less aggressive? Can you talk to this guy again? It may be a franken-Carb solution with different parts from different kits. Holy cluster phuck batman! At least the carbs are similar enough you can tune it out. Sometimes I don't know WTF people are thinking. I believe but I'm not sure that the code for the carbs on that bike is on the left side of carb number 1, maybe take a look if you can. Don't worry too much it probably can be tuned with some sort of carbs on there(uggh). So judging from what we have so far you may have a set of GSXR400 Carbs or at least the needles, a Dynojet mainjet installed on a Bandit 400.
WOW! Your right maybe spares are really expensive in S. Africa! It sounds like a third world McGuiver fix. Get the petcock sorted out and we'll talk about fixing the rest. I'm sure you can still make it work considering the only difference in the GSXR400 Carbs is the mainjet size.
Just take it one step at a time and step 1 is to fix the petcock. Step 2 would be to fix the needle valves if it's still dumping fuel Step 3 is to fix the jetting which even if it's a different set of carbs on there will still work. So don't fret it too much. Maybe there is a reason there is set of GSXR carbs on there who knows? I know that the Bandit 1200 loves GSXR parts so maybe it was some sort of performance mod or something? But without an aftermarket can and slip on it's just a waste but whatever.
BTW the Japanese models is speed limited at 180 by the CDI not by jetting or carbs or whatever and it can be bypassed I believe by snipping a wire to fool the CDI it's not in top gear but don't even touch that until the bike runs ok. Thats number 2348793724937 on the list of stuff to do.
EDIT: Ok after searching on the internet I did learn that they will interchange as the Bandit 400 engine is basically the same with milder cams however the consensus is that it's a waste of time unless you're going to from the 32mm Bandit to the 33mm GSXR400 carbs and get a can and slip on. But whether it's a waste of time or not the problem with the GSXR carbs are concerned it's almost impossible to get parts for it at least in the States. But at least you know it will work so once the fuel dumping problem is fixed at least you can make it work. Good luck!
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Howdy gang. Sorry it's been a few days, but with the internet being out and dealing with a botched suspension order i've been unable to update you guys.
Went to increase valve clearances. While doing so noticed a ghastly hiss from the crankshaft while the three and four cylinders were under compression. Decided i was going to figure out what was going on.
When inspecting pistons, rings, and cylinders, everything looked gorgeous. Rings nice and springy, cylinders, while not completely without sign of wear, showed no signs of warping or notable distortion. Number three and four spark plugs were that beautiful tan color that I hear so much about as to a happy spark plug...which was interesting as the three and four cylinders were DEFINITELY the ones hissing(i confirmed this by inserting one plug at at time and listening for sounds).
Since the three and four cylinders were the ones giving the sounds, i thought maybe it might be the head gasket. The head gasket was nasty. Cleaned it up with petrol and some fine grit sandpaper...then sprayed it with a coat of spray paint and replaced, quite optimistic that this would cure my woes.
No go. When everything came back together, the hissing sounds were just the same. Reset the timing, then increased the valve clearance on the intake side up to .2mm. Didn't help. Bike still behaves exactly the same. Starts when cold, can hardly keep an idle when warm and won't start.
SOOOOO......let me recap the condition of the spark plugs....one:rich two:way too rich...nearly fouled. Three: Happy brown color. Four: Happy brown color.
Interesing as it seems to be cylinders three and four that are losing compression, no? My friend and i chatted and decided our expectation would be that a leaking cylinder would cause that cylinder to run more rich...as the petrol comes in, extra O2 is forced out during the compression stroke, so more petrol per volume of air, more rich, no? The spark plugs are indicating contrary to our intiution here...that the leaking cylinders are running more lean than the good cylinders! What's up with that?
In short...it sounds like this bike is a cluster&%$@ of problems. Any chance this thing will get me 8000 miles on a cross-country trip? I'm kind of financially committed to including this bike in the journey. I can handle the push-starts and the difficulty at low speeds...i just don't want this problem to get worse as I continue on the trip...and i definitely don't want to mess it up beyond repair...whatchya guys think?
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Hi rmack87
You need some more data...
I would suggest a compression test, both wet and dry, and if possible a leak down test. It certainly sounds like you have low compression on one or more cylinders, which could be:
1. Leaking valves
2. Leaking head gasket
3. Poor ring seal
Based on your comment of a bad looking head gasket, I would get a new one on order, but depending on the results of the above tests, you may be looking at the need for a rebuild. Try to get the data first, and then make a decision.
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I know it's tough especially when you want to go on a big trip. I think you're at a junction with some hard choices.
Choice 1:
Fix it properly. That mean tearing down the engine, checking the rings, pistons for wear, changing the valve springs most likely and re-lapping the valves. After that re-jetting will be simple but will still require time/and or jets and new petcock. You will need a top end gasket kit including new valve seals which may run about $200 or so. Reliability high. Cost high. Resale value will be high so keep those receipts! That's assuming it can be fixed properly.
Choice 2:
Fix it sort of halfway using whatever you can to fix it cheaply may be messy if you use say for example a liquid gasket instead of real ones. Make it work just enough to function, beat the hell out of it because you're just going to sell it for parts or as a fixer upper. Cost low reliability low.
Choice 3:
Sell it off now for parts and use what you have plus some of your own money to get another bike in good working order before going on a large trip. Least amount of work. Could be pricey if you don't get much for the bike you have. Cost medium/high Reliability high/depending on what you buy, could be buying another set of problems a bit of a risk but if you're current bike can't be fixed without major work, might be for the best.
It's really up to you, if you feel that half fixing it will do you for the trip then go for it. If you want to totally strip it down and rebuild it to get a good resale value you could go that route. For myself I would either fix it completely or just sell it and get something else. I know it's tough, but do you want to be broken down somewhere in the wilds of Africa with a dead bike and no money to buy another? It's up to you, since you drive it daily you would know way better than any of us how your confidence level is. I would have another go at it at least, see what the damage or potential for fixing is then decide. I've had to sell bikes that I knew were too much money to fix up so I know how it feels, but sometimes you have to cut you losses. Or on the other hand if you love the bike and want to keep it for at least a year it may be worth it to fix up. If the valve springs are slightly phucked it's not that hard to fix, it's mostly just labour and the cost of the gaskets/springs and what maybe $5 for lapping compound. If the pistons and rings are in good shape it will basically drive like new. You can do it in a weekend with a buddy, just supply some beer and have fun. Just take a few days and take another look and sit down with a beer or two and have a no bullshit assessment for yourself and your safety on a long trip.
If you want when you check for the hissing sound put your ear right up to the exhaust side of the bike as well as the intake side near the boots. After that check near the bottom of the crankcase to see if you have that hissing noise. If the pistons as you said looked in great shape as well as the piston rings are in spec. My guess is the valve springs are dead and the valves aren't sealing properly. If the hissing is at the top end then that is most likely the problem. If it's at the bottom then your rings are dead. If it's the valve springs you're in luck as it's not that hard to fix, mostly just work. Under $400 for sure including all gaskets. Once the valves are sealing properly it will be super easy to fix the jetting, probably just a notch or two down on the needle and a screw adjustment. But find out exactly where the leak is by listening to the top of the engine and the bottom. My guess is as the cylinders and valves are heating up, the metal expands and allows a small leak to form, killing compression. If the rings were phucked it would do that from the first second you turned the bike on, not when cold or hot. Try with your ear to hear whether the hiss is at the top or the bottom. If it's the top and the exhaust valves are leaking you will definitely hear it at the exhaust pipe and it will have a hollow sound like blowing through a beer bottle or a tube.
Put it this way if you do fix it properly that $400(probably more like $250-$300) may turn into $1000+ at selling time. If the bike is dead you may have alot of trouble trying to get rid of it and may only get a few hundred bucks compared to $2000 if you keep all receipts and fix up the jetting properly which is super easy. I did it on a GS750EF because I wanted to drive it another couple of years and I kept the receipts and actually sold it for $500 more than I bought it for so it worked out well. After 20 years I would wager the springs are tired, mine were. When we took a look at the rings there was hardly any wear at all and all were well within spec. The springs are the weak point in the engine, as long as the oil is good it will do it's job well and the rings will be fine. While we had access to the head we got all the coking out of there and polished the piston crown and when put back together was literally almost a new bike. If the springs are dead and not sealing, NO AMOUNT of adjusting the valves will fix it.
If you do want to fix it we can help you out, it's not hard just a bit of labour. I might be able to help with some tips as I did it myself. The springs are a no brainer, the key is making sure those valves are nicely lapped and cleaned so you get a good seal. I highly recommend getting a friend to help you out, it makes the time go by quicker and reduces the labour in half, also when taking out the block and popping it back in there it makes it alot easier. You may be able to squeeze the block out of there without pulling the engine if you're lucky. Since I did it over the winter my friend and I pulled the motor but it might not be necessary for the 400 as it's a smaller engine. If you're working solidly you can do it in a weekend or less. The hardest part is putting the block back on and manually compressing the rings one layer at a time to feed the pistons back into the block, you definitely need an extra pair of hands or two but only for like 15 mins or so then your set.
This is what you need for your own info and decision making:
At least one or two cases of beer(most important) $35
A valve puller, basically just a wooden or plastic dowel with a suction cup on the end $10-$20
a good tool set, which you probably have
valve lapping compound $5-$10
top end gasket set $100-$150(if doing it on the cheap may be able skimp if you don't care in a year, or gaskets in good condition)
new valve seals another: $50-$75 (if not in top end kit)
Optional bottom end metal gasket $30(I didn't bother as it was in good shape and had no leaks afterwards)
Some light steel wool to clean up piston crowns and top end/valve coking(be very gentle)
Set of valve springs: $100-$150
About 10 hours labour, less with more people. With enough people, could probably do it in 6-8 hours
Optional ring compression tool: $50, can use your hands if you have enough people to help feed pistons and rings into block when assembling.
Here is the options with this sort of fix comparing cheap/full fix:
Cheap/minimum fix:
With this fix you are fixing the problem but skimping on the top end gaskets, which may leak but are super easy to change out as when the next valve adjustment comes along you'll be changing them anyway. Same amount of labour, maybe save 40 mins by not changing out the gaskets.
Beer: $35
Valve puller: $10-$20
New valve seals $50-$75(skimping is not an option!)
New valve springs: $100-$150(skimping is not an option!)
Valve lapping compound: $5-$10(skimping is not an option!)
Light steel wool
A good tool set
Labour: 10 hours or 6-8 with enough people
A few extra pair of hands
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Whoo! Thanks for all your support, guys. I've got some decision making to do. I want to get a leak-down test before making a definite decision, but in all likelihood i'm locked into using this bike, more or less ass is, for the trip. The trouble is finances. It's safe enough, it moves around at a decent pace, and is able to handle some off-road...which makes it more or less do-able, esp. With two other guys with more reliable bikes. If I get stuck, i'll always have the option to just ditch the bike at the nearest shop for a pittance and fly back to the states, or even trade-in for an old scrambler that can get me around in less comfort. It's a shame though, because i don't like the idea of being the end-line of a bike's life!
From what you say, i don't think it's the top end giving the problems. The sounds(it hurts me so much to say it) are coming from the crankcase. The cylinders must have some wear that is difficult to note by just see and feel. Deinitely no sounds coming from the intake or exhaust mainifolds. I was kind of hoping that somehow it was that head gasket and the sounds were somehow leaking from there down into the crankcase via an oil inlet or something. Now I see that was just wishful thinking.
Its interesting as this bike doesn't eat up oil---if it does, its hardly noticeable. Another one of these bikes we have I suspect has a bad cylinder or two due to consuming oil but it starts and pulls through the whole range of revs just fine.
Does anyone know if it's better to run on the rich or lean side for a leaking cylinder? That may help a little.
My last question is regarding engine oil for all of the bikes. Being older, I'm guessing a thicker weight oil is better for these engines. 20W50 is common in africa as there are mostly older vehicles on the road. Is this okay for these bikes?
I've got some serious decision making to do! Thanks a ton guys for making this so much easier for me than it could be!
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If it's not eating oil then your rings are probably fine, otherwise it would eat oil like crazy. If you can just drive the crap out of it then go for it. As far as jetting for dead cylinders it's not going to make a difference one way or the other so enjoy the bike as is. At higher rpm you're just going to get alot of valve float. I'd say it's fixable but that is decision best left for yourself. Hey, when you get to the States you can pick up the big brother Bandit 1200 for a very reasonable price and have triple the horsepower.
Does the crankcase oil smell like gas or is cloudy? If not the rings are probably fine. Since it's such a small engine it would be kind of hard to see if the hissing is crankcase or valves, the only way would be to take it apart and/or do a leakdown test. You could check the exhaust and see if any air is leaking when doing the test. Usually when there is a loss of compression it's the weakest link that goes first, ie the valves. Usually when rings go there is a whole other set of symptoms that go with it. White smoke out of the exhaust, high oil consumption, oil fouled plugs, fuel contaminated oil in the crankcase, etc. Since you have none of those symptoms the only logical and most common problem is probably at fault. Maybe when you get back from your trip, it might be worth it to fix up just so you don't have to take a huge loss when you sell it. For $300 and a weekend it will turn into at least another $1000+ when selling time comes around. I'm sure if someone said I'll pay you $100+ dollars an hour to help me fix my bike you wouldn't pass it up, if that helps you think of it in another way. Don't worry you aren't doing any damage by driving it around all demented(unless a valve spring goes then you won't care if the bike is dead) so you could fix it if you wanted when you come back.
Also when the engine isn't running, the piston rings aren't compressing against the cylinder wall so it will leak there slightly even with a brand new engine out of the factory.
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If the bike runs ruff and the plugs look black the first thing you should do is renew the o'rings in the carbs.
This is a well documented problem on old bandit and gsxr4's and gives the exact symptoms you post.
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Holy carp that was probably the magic button! The vacuum rings had been replaced by mech recently but the float seat/choke ons had not. Hah...4 rand worth of parts gives me 4,000 worth of selling value...hell of a magic button.
Took it on a small ride and it is starting right up when hot! Going to open it up later today. Honestly the o-rings looked slightly warped but not bad enough not to seal. What is the mechanism for how this ruins the running the bike? I would expect it only to matter when the choke is open! At any rate i'm stoked.
THANKS SO MUCH RIDER for your great advice and really taking time trying to figure this out. And thanks chris H for taking the time to read this crazy thread and come up with an answer.
Will let you guys know later after my ride if thiis issue is for sure resolved....but i'm pretty optimistic at this point. Cheers!
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Awsome glad it worked for you. Now on to the petcock! :grin:
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Im not saying it is the o'rings JUST that its the first thing after plugs etc i'd renew.
The important ones are the pilot screw, two in the float and the large one thats under the white plastic slide holder.
They MUST be viton, you cannot fit the cheap nitrile ones from the DIY store, i can supply a full set if you cannot get them yourself.