Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: PitterB4 on May 09, 2006, 03:07:08 PM
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I was going to PM Jay but figured I'd share with the group...
Hey Jay,
You always say a good way to tune is to see if problems get better or worse when you run w/out your airbox. With my new set-up:
* throttle resp is very good down low.
* it positively pulls like a train up top - all the way to the r/l.
* at normal backroads speeds, it's not quite as crisp powering out of turns as it should be. The problem is just barely noticeable but once it's warmed up, roll-on out of a turn at ~7k just isn't pulling on my shoulders like I would like. :wink:
* the 4-5k flat spot is very minor and only lasts about 2 minutes.
So, I pulled my filter and popped the tank back on. Down low, I'm still ok. That 7-9k, 1/2 to WOT range, I've got NUTHIN'! It boggs something awful. I have to feather the throttle to get above that rev range. Once above, it runs OK again. Not great anywhere but OK low and high and almost not at all in the middle.
Your diagnosis, sir? (I'm thinking I'm lean on my floats. If so, how much adjustment at a time. Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)
BTW - my settings:
* V&H headers/M4 can
* FP TI needles - middle position
* AF screws ~2.5 turns out.
* 110 mains
* Floats, stock height (~14.5)
* Airbox with a golfball sized hole on either side of stock hole. Snorkle in place.
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put 112 mains in and if i did anything i would just shim the needle one way or the other, dont mess with float level i found out this weekend it changed my whole jettting by only going 1-2 mm different in float height.
the question is did it run better on the top a little learner? did it pull better from a a dead stop till i fell flat on it face? Its a matter of finding out what worked and writting it down and from there if it was good or better on the bottom get 1 size smaller pilot , and the same for the main if it ran noticable better , but is also good with the air filter in try a 108 or something like that main , what your saying is your bike wants fuel in the mid range on the needle , If it where me I would have raised my needle up to see if it rain better with the air filter out and more fuel to the needle. See i bought this thing from k&n called like a color tune has a ega thing that goes into my pipe and reads if im rich or lean i love it verey handy and i think it only coast 150.00 USD.
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It was worse everywhere - almost unrideable in the middle. The bottom wasn't bad but still worse than with the filter. It was hard to get into the upper ranges but the couple times I did, it didn't pull as well.
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Jay - is this (http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200310599_200310599#productinfo) the Colortune thing you're talking about?
(http://www.northerntool.com/images/product/images/16749_lg.gif)
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http://www.knfilters.com/airfuelmonitors.htm
this would be what i bought.
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there is this one to but it was a bit pricy for me and has a few more features, like you can hook it up to your computer
I didnt need all that and the one i got work great for at the track
http://www.widebandcommander.com/
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Whilst this threads here i may as well ask - on a bike with a K+N filter and race can, is it worth fitting some GSX-R carbs? What will i gain/lose? Also, will my Dynojet kit for the Bandit fit/be worth fitting?
Thanks in advance. :thanks:
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yes that is the best thing you could do unless you have a model that already has the 33mm carbs and yes the jet kit fits in the gsxr4 carbs, more power
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I was going to PM Jay but figured I'd share with the group...
Hey Jay,
You always say a good way to tune is to see if problems get better or worse when you run w/out your airbox. With my new set-up:
* throttle resp is very good down low.
* it positively pulls like a train up top - all the way to the r/l.
* at normal backroads speeds, it's not quite as crisp powering out of turns as it should be. The problem is just barely noticeable but once it's warmed up, roll-on out of a turn at ~7k just isn't pulling on my shoulders like I would like. :wink:
* the 4-5k flat spot is very minor and only lasts about 2 minutes.
So, I pulled my filter and popped the tank back on. Down low, I'm still ok. That 7-9k, 1/2 to WOT range, I've got NUTHIN'! It boggs something awful. I have to feather the throttle to get above that rev range. Once above, it runs OK again. Not great anywhere but OK low and high and almost not at all in the middle.
Your diagnosis, sir? (I'm thinking I'm lean on my floats. If so, how much adjustment at a time. Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)
BTW - my settings:
* V&H headers/M4 can
* FP TI needles - middle position
* AF screws ~2.5 turns out.
* 110 mains
* Floats, stock height (~14.5)
* Airbox with a golfball sized hole on either side of stock hole. Snorkle in place.
Rob put it back together and just shim the needles a half a step see if that fixs it , but it is hard to just get rid of a minor flat spot usually you move it some where else. you have a better chance of removing a flat spot by degreeing the cams but thats a different ball game all together.
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Thanks, Jay.
Just to be clear (I typed a lot!), the only concern I have is the 7-9k 1/2-WOT roll on.
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yes try to shim the neddles
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Boy, I hate pulling those MFing carbs again!!!!!!!!!!!!!)
Suck it up.
I had mine off 3 times on Sunday. 10 am until 6 pm without stoping. :crybaby:
And I'll probably tweak a bit more this weekend. I'd like to go do a dyno run soon and I'd like to have the jetting as perfect as possible.
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yes that is the best thing you could do unless you have a model that already has the 33mm carbs and yes the jet kit fits in the gsxr4 carbs, more power
Thanks. Any way of me knowing which carbs mine are? Its an early jap 400.
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Rob I really suggest that termostat swap before dicking around anymore with your settings.
It made things that much more consistant on my bike and all I have is a Dynojet kit, Cobra pipe and a slightly modified airbox. The bike warms up in about two minutes and throttle is much more consistant across the board. If you're draining your coolant anyway for the track day, why not?
-Randy
Oh and as I side note, I run an AF meter in my car and what a difference it made tuning it. A wideband is so much more accurate but so much more money at the same time. Much, much easier to dial in fuel at different load levels
Rob, if you're playing around that much, you can have your exhaust shop (they should know you by name by now and buy you cookies at Christmas) weld in an o2 bung just aft of the collector in the midpipe somewhere and install one. After that, it's three wires to wire in an AF meter and they now make them small enough to mount anywhere.
Just a suggestion...
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AFAIK (which is not exhaustive by any means), the US was the only market to get the 32s. I can't imagine the Jap version would use them. You probably have "GSXR Carbs."
Mike - carbs are definitely coming off again. I was still using my old, pre-Kreem fuel filter. Tore things apart, put it back together.... with the gunked up filter on BACKWARDS!!!! Washed all kinds of garbage in. Can you say "blocked pilots?" Oh the joys of carb cleaning!!!!!!!!!! :banghead:
Thanks, Randy. Just another thing I need to get to. I've already got Engine Ice in there in place of regular antifreeze which is one of the reasons I've been hesitant to do it.
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I continue to get emails asking me about carbs and O-ring problems, so here's another summary which I hope includes everything anyone needs to know. In any event, it's just about everything I know.
It being that time of year when a whole new bunch of owners discover their pride and joy is running like a pig, here's a primer...
The Mikuni carbs on GK76a use O ring seals in 3 different locations, any or all of which cause carburation mayhem as they harden with age, heat and fuel immersion. GK73a and GK71f types may or may not be similar, beyond my experience I'm afraid.
Symptoms of leaky O rings and poor carb setup include:-
- cold starting without choke
- rich running/poor MPG/sooty exhaust/spark plugs
Both the above need attention quick. The O rings are almost certainly leaking and WILL allow excess fuel to wash the bores, which WILL result in excessive and rapid piston/bore wear and a totally knackered engine that needs £hundreds spent on a rebore.
- stumbling and jerky pickup from low revs
- hard hot starting
- poor low/mid throttle response, but OK at higher revs
May just be carb balance and slow-run mixture adjustment. But if accompanied by rich running and no need for choke when cold, you're looking at a carb rebuild.
Carb removal and strip:-
This isn't hard. BUT BE AWARE THAT PETROL IS EXPLOSIVE AND WILL KILL YOU GIVEN HALF A CHANCE. You have to get the carbs off which looks an impossible task. Obviously tank, seat, fairing need to come off. Disconnect the battery to avoid spark risks. There's a rats nest of hoses, breathers and cables and sh*t to be disconnected. Everything can be left connected at the carb ends. Take a picture/make a sketch so you know where it all goes back.
- undo jubilee clips between carbs and inlet stubs, and carbs and airbox stubs
- release throttle cable at the handlebar end
- release choke cable at carb end
- unplug TPS (SP only)
- withdraw the 2 large wire clips that retain the airbox stubs, and push the stubs back into the airbox (pushing them back onto the carbs later is easier with the filter removed).
- this will give you enough room to pull the carbs off the inlet stubs and feed them to the offside and remove the entire bank, along with the attached hoses etc.
Unless you need to for other reasons, don't separate the carbs, leave them in a bank. You need to get the float bowls off and also the diaphragm covers. Be warned : these Philips head screws are sods, and apt to corrode in place. At the very least you need a decent, properly-fitting screwdriver, but gentle use of an impact driver is far more likely to work without mashing the heads. Altec also sell caphead M5x12mm stainless steel bolts (code 114-6444, £10 for 50) which you can use to replace the OE Philips rubbish.
The offending O-rings are:-
- around the body of the float perch/shutoff valve holder, the pinky/orange plastic piece. If this leaks, petrol simply bypasses the shutoff valve and overfills the float bowls. IME this is the most problematic of the 3 locations, since the plastic body is a loose fit and the single securing screw allows it to wobble around if the O-ring is knackered.
- around the slide holder base, the large plastic piece that the plastic slide runs in. A leaky O ring here will bugger up differential pressure on the diaphragm and mess up throttle response and mixture progression
- around the main jet, sealing it into the carrier. Another potential disaster, as leaks here will be like having an oversize main jet fitted.
'What O-rings do I need?'
Our bike is a 1994 GK76a SP with Mikuni 35mm carbs with TPS, but all other GK76a's 33mm carbs use the same O-rings. Any other models I DON'T KNOW - you must make your own inquiries.
You can buy OE replacements from Suzuki but they cost a mint and are exactly what caused the problem in the first place.
Wherever you get them, obtain Viton rather than Nitrile rubber at least for the perch and mainjet O rings. Viton is petrol and heat proof.
http://www.altecweb.com are a UK site who sell 2 out of the 3 types
Altecweb quickorder codes for Viton O rings
ORV BS010 mainjet holder
ORV BS011 float perch
These are £4.05 each for a pkt of 50, a lifetime's supply. You only need 4 of each type.
These are Imperial sizes and a bit snugger and fatter than the OE metric, which is a GOOD THING - especially in the case of the float perch, where the OE O-ring is a poor seal in the carb body even when new.
You will also need 4off 10mm ID x 1mm for the slide holders. Altec don't sell this size in Viton or Nitrile.
Nitrile (standard material for O-rings) seems OK in this location as they aren't immersed in petrol. Halfords and B&Q sell mixed packets of O rings, one of which contains some 10mm x 1mm. Unfortunately I can't now remember which shop - B&Q medium size assorted O rings, I think. They're cheap enough, a quid or so per pack.
DO NOT be tempted to use any of the other nitrile O-rings in the pack that might fit the mainjet and float perch, nitrile is NOT good for immersion in hot petrol and they'll deteriorate rapidly and you'll end up doing them again in a few months.
Using these O-rings has worked well here. The bike continues to run like a watch and be completely free of carb problems 6m later.
PLEASE NOTE : assuming good engine condition, good plugs and aircleaner, you will need to check the valve clearances AND balance the carbs as accurately as possible AND adjust idle mixture on each carb VERY carefully in order to resolve carb problems. In that order.
Do NOT f$ck with float height settings unless they're wrong. Unfortunately a lot of people try and fix excessive richness (due to leaky O rings most often) by messing with float height. It won't work. It just makes things more confusing. Unfortunately #2, the Jap manual for these bikes (GK76a) contains no intelligible information about float height, so once someone had messed with them there's no way of knowing what they should be. The occasionally-quoted 2-4mm at the perch is impossibly vague. All I can tell you is that the float heights on our GK76a SP are 20.5mm measured in the conventional manner (float bottom to carb flange when shutoff valve just touching seat), and this works fine here. Other models may be different.
These bikes are just amazingly sensitive to carburation. Small adjustments make large differences on these bikes. The patience of a saint, accuracy and perseverance are essential. The difference, once sorted, is remarkable - even the SP is able to pull cleanly from tickover. Skip anything, and you're liable to get nowhere.
I can balance and set the carbs on my GSXR1100J in <10minutes, the same on the 400 took me most of last summer through lack of info and trying to cut corners. I had the carbs on and off more times than I can count - 3 times in one day was my record. Take it from me, it's worth doing it once thoroughly and properly.
Carb balance is tricky to achieve (I use Morgan Carbtunes inverted - excellent kit), but the breakthrough insight is that idle mixture HAS to be set on each carb too. Most bikes don't need that messing with. After experimenting with Colortune I realised it just wasn't accurate enough, and found it much better to just adjust each slow-run screw by ear for the most even running. It's then worth going back and readjusting balance.
If you run a race can and/or aftermarket aircleaner, you will also need the assistance of someone with a dyno to sort out mainjet and needle issues. Unless you do that, it's unlikely you'll be able to get the bike to carburette properly - unless you're sufficiently skilled that you don't need any of the above advice.
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Regards Tony
(snaked from another board from Tony aka halftone from http://www.400greybike.co.uk/forum/topic.asp?FORUM_ID=20&TOPIC_ID=43615 on may10th, 2006
hope it helps some one out!!
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This is flippin brilliant, Jay. Thanks, man. I'll separate that post to it's own thread in the FAQ tomorrow...
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Say Jay,
now you mention it, where exactly do you place the A/F sensor? in the 4-to-1 part? is it hot enough? Or did you do something exotic like welding it closer to the engine in each separate pipe?
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That was an idea I presented to Rob.
You would want to weld it just aft of the collector, close enough to get the flow of all 4 pipes but far enough so it isn't "in" the collector. If you use a self-heating O2 sensor (anything with more than 1 wire) light up is very, very quick. You can use a single wire sensor, but it would take a smidge longer to heat up and read.
If you have a welder and fancy a try yourself, you can use a spark plug non-fouler in 17mm from the Help section of yous FLAPS and use that as a bung to weld into the pipe. Bosch O2s screw directly into that.
-Randy
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Say Jay,
now you mention it, where exactly do you place the A/F sensor? in the 4-to-1 part? is it hot enough? Or did you do something exotic like welding it closer to the engine in each separate pipe?
Right after it hits 4 into 1 , yes it one wire takes less than five minutes to start working needs exhaust temp to be 600 degrees F. very cool i wouldn't trade it for the world now that i own one. :beers:
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Ya they work pretty sweet, and if you take it the next step and use a wide band O2 sensor the resolution is even better. Instead of working between .1 to .9 volts you now have between .1 and 4.99 volts
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The O-rings that Jay is reffering to can also be ordered from a company in the Toronto area. They have a $25.00 minimum order. Talk to Doug at Global Rubber (http://globalrubber.com/index.html)
G
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I get along with carbs about as well as I get along with my mother-in-law.
Are these the o-rings that cause all the problems?
(http://homepage.mac.com/garyola/.Pictures/0ring.JPG)
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yes sir
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The idle on my bike has been a little funky. At times, it is slow to drop down to the 1400 RPM level. Other times, it drops really low (~1000 RPM) and as a result, there is a little hesitation on rev up.
I have disassembled and cleaned the carbs. All three O-rings were replaced. However, I did not go as far as disassembling the butterfly valves. The parts diagram shows O-rings that seal the butterfly shafts, but I didn't feel like messing with those. Jets are clean and float levels are to spec.
I have had the bike running most of the time but this idle problem bothers me, to the point where I have taken out the carbs several times to try and isolate the source.
I have tried to look for intake leaks by using a Propane probe. So far, no leaks have been found. I am having trouble with balancing the carbs. I will get the idle steady enough (1700 to 2000 RPM) to get a good balance, but then the idle changes and so does the balance.
Also, I have not messed with air screw settings. The metal caps covering the air srews are still there, and I havn't bothered to take them out.
What am I doing wrong? I need help. All input is greatly appreciated.
TIA
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IIRC, the instructions for balancing (Motion Pro's) call for setting the a/f screws to optimal/smoothest idle before synching. I would drill the plugs and play with the screws. Your symptoms are certainly that of cabs needing screw-setting and synching. Good luck.
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I get along with carbs about as well as I get along with my mother-in-law.
Are these the o-rings that cause all the problems?
(http://homepage.mac.com/garyola/.Pictures/0ring.JPG)
You all know or if you dont you will now that you are to use di-electric grease or some sort of other seal grease when you push these into place on your carbs. cheers just a FYI :stickpoke:
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:duh: I know now. :thanks: