Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 600 thru 1200 - AIR/OIL COOLED TECHNICAL => Topic started by: brainsick on March 14, 2013, 11:39:17 AM
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Hello all,
I've been bangin my head against the wall with my 99' bandit 1200. The bike idles, revs, and runs perfect until about half way through second gear and above then it breaks up/stumbles and acts as if its not getting fuel, can only run about 1/4 throttle.... Push the clutch in for a second and I can start back off for a couple more seconds than it breaks up again.. First gear will lite the tire off and second will start to pull then nothing. The kicker is the bike ran perfect about 2 weeks ago, all I did was pull the tank and body panels off, painted them, reassembled and went to take it for a ride and nothing but problems... Since the issue arrose I thouroghly went through the carbs cleaning all jets and blew through all journals, checked float heights, rebuilt the petcock, checked for any vacuum/intake leaks, checked for venting issues, no issues with debree in the tank, cleaned and checked every electrical connection/grounds, new spark plugs, checked for shorts in the plug wires, I even tried gutting the petcock and installed an inline valve thinking that maybe the new diaphragm was defective but no improvements and is flowing fuel... Has anyone experienced this type of issue? Like i said it will pull hard until after second gear....??? Any help would be much appreciated. Thanks
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Now I've not come across that one before. With it reving perfectly in 1st that decreases the chance of it being fuel related, however as that is the main area you've been looking that does strike as odd. What sort of temps/humidity are you riding in? If you're UK based then it could be carb icing, as that would be causing the bike to stutter (sound as though it's missfiring), and you would slowly be able to use less and less of your rev range. Once you left the bike off for a few mins you would be able to rev freely again for a little while, however this normally affects all gears, not just 2nd and above.
Hopefully someone else will have experienced your problems themselves, and be more knowledgeable than myself.
All the best,
Bullet5.
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I just wanted to add that I swapped the coils with a known good set and still the same issue.... At the moment our temps have been between 30-60 degress F with very little humidity, so icing wouldn't be an issue, thank you for the response though bullet5.
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any chance of an air leak? (my bike stumbles in heavy rain and I have to keep the rpms up)
Checked plus & wires?
Do you rev it that hard in the higher gears? Typically there isn't enough room on the road to do that.
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Definately no air or vacuum leaks, triple checked that, I replaced the plugs and checked the wires by misting some water onto them and no shorts, I cant get the bike passed 1/4 throttle in any other gear than 1st and if Im lucky 2nd but then its just acting like its starving for fuel.... First time I've ever delt with this kind of issue... I want to add also I swapped out the pulse generator with another known good one thinking maybe its not getting the timing and still the same issue... I'm beginning to believe my CDI is the culperate....??? Any other ideas would be great. Thanks
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Another addition to this seemingly impossible mission to trouble shoot this issue, I just swapped out my cdi box with a known good one and the bike has no improvements, still the same issue...... I'm running out of ideas, does anyone else have any words of wisdom????
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How did the plugs look when you replaced them? How do they look now?
You may have checked these, but here are some things you haven't mentioned:
1. Check the airbox and air filter. Make sure it's clean, and that you're not building up anything in the bottom of the air box.
2. Try riding with the gas cap open, to eliminate any chance of a venting issue.
3. Make sure the Choke (enriching circuit) is fully closed.
4. Remove the in-line filter completely to make sure there is no restriction in the supply.
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How did the plugs look when you replaced them? How do they look now?
You may have checked these, but here are some things you haven't mentioned:
1. Check the airbox and air filter. Make sure it's clean, and that you're not building up anything in the bottom of the air box.
2. Try riding with the gas cap open, to eliminate any chance of a venting issue.
3. Make sure the Choke (enriching circuit) is fully closed.
4. Remove the in-line filter completely to make sure there is no restriction in the supply.
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I know you said checked it, but I still think it has to do with some kind of vacuum issue with the gas tank.I don't know if opening up the cap would make any difference,but it just seems like I remember something similar years ago . Don't remember if it was on this site or maybe Bandits R US ? Make sure the vent hose isn't kinked,and I think the issues that I remember reading about, might have been in cold weather.( My bike LOVES the cold crisp air.) Don't know why that would make a difference. But I would check plugs. If they are rich, then that would not be it. And lighter if they might be starving for fuel.
Granted, I'm a tile setter not a bike Tech.But for some reason I think your running out of fuel and might be a simple fix. Just have to find it first. Dan
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I would agree with the general statements in this post. I highly doubt you did something catastrophic. I would recomend lifting the tank again and check to see if a vacuum or fuel line got pinched in the process. Let us know how you make out. The reason that your bike or any for that matter likes colder air is because the oxygen molecules are more dense which gives better combustion, which equals more power....enjoy it :grin: Although it could be that your running a bit rich and the colder air will lean it out a bit. See how you make out. If not you can PM me and I'll give you my phone number and we can go through the checklist.
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Pmackie,
The plugs removed and the current new plugs are a perfect golden brown, Air filters are clean, tried running with the cap open same issue, the choke is working and disabled, and there's currently no inline filter or blockages in the fuel line.
Thank you for the help!
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Smooth operator,
I don't know how it could be vacuum issue because everything is checking out.. There is only one fuel feed, one vacuum line, and one tank vent line and they are all free and clear. The tank is venting when I remove it and shake the fuel around , also there is no change in flow when I turn the petcock to prime and open or close the gas cap. As far as being cold the temperatures are currently around 48 which is right around the same temps as it was the last time I rode it with no issues... I really hope this is a simple stupid fix, but at the moment I'm at a loss for words.........
Thank you for your help!
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I just like to try all the easiest things 1st. Hopefully it will still be a easy fix,the hard part is finding the problem. You have already been doing that,and now I'm scratching my head too. After I posted I pulled my tank, (98 B12) and just took a look to see if I can think of anything.
I wanted to check over my steering dampener mounts anyway.Make sure all fasteners were secure and a visual check over everything.(found a loose bolt that mounts to the clamp on my right fork tube for the dampener. )
So now, without going back over all the older post, I'm thinking carb.
Everything clean,all O- rings are good and present. Check all jets are clean,needles move freely. I guess just go over the carbs and hope you find something. :beers:Dan
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I would like to add some information about the bike to see if maybe I'm overlooking something because I can't figure out this issue.. It has k&n pod filters, 150 main jet, 35 pilot, needles are set on the 3rd clip down from the top, custom exhaust, air mixture screws are set at 3 turns out, and it has a + 5 degree timing gear on it.
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I would like to add some information about the bike to see if maybe I'm overlooking something because I can't figure out this issue.. It has k&n pod filters, 150 main jet, 35 pilot, needles are set on the 3rd clip down from the top, custom exhaust, air mixture screws are set at 3 turns out, and it has a + 5 degree timing gear on it.
I have the same set up except I have 32.5 pilots and my needles (hole shot needles) are 2nd notch down.
Wasn't your bike running fine before with the set up you all ready have?
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Smooth operator,
Yes the bike ran perfect with this exact setup. I'm just trying to make sense of this issue because nothing I try has any improvements, so at this point I'm second guessing just about everything... Thank you for the response
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Hey brainsick
Again a simple one. Drain the tank completely, and add fresh fuel with no ethanol in it? Ie: get rid of any possibility of water or alcohol.
Otherwise, your describing a problem occurring under high load/low rpm. Check the carb slide boots carefully. A torn boot could wreck havoc with the vacuum slides.
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Pmackie,
I did drain the fuel and put in new thinking that maybe I had gotten a bad batch, unfortunately its almost impossible to find fuel around here without ethanol in it, so I added some stabilizer.... The vacuum slides are fine, no dry rot or cracks..... STILL STRUGGLING...
Thanks for the help!
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I've been using Star Tron,put a little bit in a 5 gal. can. There are other brands too,but it gets rid of the ethynol. I use it for my bike,lawn mower,chain saw, especially over the winter. And I'll go through almost a tank over the winter just starting the bike up till its warm.
Mine good use a good run about now! Its 31 F here now,and the roads still have a lot of salt and gravel on them. Could use a good rain or two to get them cleaned off a bit.
I think I'd start out with some fresh fuel too. Get some of the additive and try it again. And if that doesn't help,I'd go to the carbs next.
:beers: Dan
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I have near 100 miles on the bike now since this issue came about, back and fourth, up and down the road, tried every combination of senarios that I could think of, still no improvements..... I tried wrapping the K&N pods with rags to see if it was possibly getting too much air, ran worse, tried the opposite and ran without the filters, still running like crap.. The only improvements I can get out of it is if I work the throttle and choke together in different positions somtimes it will take off and then die out again a moment later... The carbs have been off 25 times now, Choke circuit is definately clean, all passages in the carb are definately clean... The slide diaphragms have no visual cracks or rot and all raise and lower at the same time when revved on the lift.... I jacked the back tire up, ran the bike on the lift, no issues until actually riding... I really don't know what else to consider with this thing.... Any other help would be great. Thanks!
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Alright, time to change gears...
Maybe check compression and do a leak down test.
But it sure sounds like carburation issues. What are the float levels set at?
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Pmackie,
Compression is near 125 psi on all cylinders. The float heights are set at 14.7mm but it doesn't seem to make a difference where the floats are set, I tried high and low.. Same deal.. I'm almost considering buying new slide diaphragms but the dealer wants $60 per unit... Think its possible that these are bad and causing this issue?
Thanks for your response!
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If the boots look in good condition then I wouldn't change them, BUT make sure they seat correctly in the top of the carb body. You can use a LITTLE grease or petroleum jelly.
I know you said you've done this, but are you SURE that the O-rings on the top of the carb slides are in good condition and installed properly? Are all the vacuum ports (used for balancing the carbs) capped with caps that are in good shape and seal properly.
It seems so very unlikely, but is there any chance that the cam chain has jumped a tooth on one of the sprockets? Pretty out there, but I'm also scratching my head...
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Pmackie,
Definately no vacuum leaks, the o rings are new and I even ran a small bead of silicone across the tops of the diaphragm caps, the vacuum caps are all good as well. I pulled the valve cover, cams are in time and valves are all in spec.... :banghead:
Thanks for the help!
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How long did the bike sit when you pulled all the plastics off? This is a bit of a stretch, but on my last bike when I let it sit for a while the transmission seemed to "clump" together. When I pulled the clutch in, it wouldn't disengage from the engine, and occasionally I'd get s sticky gear (shift to 2nd instead I'd get 3rd or forth and stall). I put a small amount of seafoam in the oil and ran it a little bit and that did the trick. I know the transmission and the clutch operation are different on this bike then the gs500 but, maybe...just maybe it will help.
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This is what I would do before you start spending $$$$$$
1. Drive the bike around in the "crappy zone"
2. Pull the plugs and take a look, this will tell you if you're getting enough fuel in there or not.
It could be that your CDI unit is frazzled. Do you have a friend with the same bike? You could swap for a test. I had a CDI unit go on a GS750EF and it did all kinds of wonky stuff. There are different ignition curves for the different gears of the bike. This problem doesn't crop up in any other gear does it?
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mchollan2112,
The bike sat for roughly 2 weeks during prep and paint, the transmission is definately working properly, just seems to be a definate fuel issue but I cannot understand or figure out why...? Bought new diaphragms, and synced the carbs, still the same issue.
Thanks
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rider123,
The plugs are burning perfect, nice golden brown and the cdi was swapped out already with a known good one......
Thanks
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I just wanted to add that I swapped carburetors with another set and the issue is no longer there... Any ideas with what could be wrong with my carbs to cause this issue? I replaced all o rings except on the outer ends of the butterflys and blew through every passage, carbs are clean as could be...? I also Synced them, just seems like its loosing pressure internally and can't drawl the fuel up from the bowls...? I've read about emulsion tubes wearing out but mine don't appear to be oblong..? Any further help would be much appreciated. Thanks
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Could be a weak spark problem. With the plugs out of the motor but in the spark plug cap, hold the cap so the spark plug is app 1/4" off the valve cover then crank it. It should be able to bridge a 1/4" gap and make a spark.
Have you checked the fuel lines? A kinked line can send you checking everything else.
Have you ran the motor off an auxiliary fuel tank to see if it exhibits the same symptoms?
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From your last post it appears you have positively identified the carburetors as the problem. One of the things that I have seen even other mechanics overlook is the air bleeds for the main jet. Usually a small opening or tube at the bottom of the carburetor inlet. If these air bleeds are blocked it will run so rich that it usually falls on its face when you start to open up the throttle.
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Don't know if this helps but I had a similar problem when I rebuilt my carbs on a 400, it would take off like a bat out of hell and then quickly die in the arse. The problem was in reassembling the diaphragms, I put the spacer under the needle, I know, stupid right, so it would run fine on the slow circuit, but as soon as the slides started opening the needle would stay up and i'd be running super rich, causing it to die real fast. I know your bike was running fine before the the painting, it just sounds similar to the problems I was having so thought I'd put it out there