Cleaning / Rebuilding the carbs - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 1 (permalink) Old 01-15-2006, 03:51 PM Thread Starter
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Cleaning / Rebuilding the carbs

I had the same problem on my '97. I posted a while back and followed all of the suggestions (which you have received also). Drained the carbs. Shut petcock and ran until empty. Used Seafoam MANY times. They all fixed the problem for a single ride, but as soon as the bike wasn't used for more than a couple of days, the problem would come back. THEN, someone posted a suggestion that has worked for my '97!!!! Drain the carbs and then SPRAY Gumout up through the hole where the gas drains out. You need to rig a small hose to get the Gumout up into the carb through the drain hole. You should also fully remove the drain-screw (so the Gumout can get up into the float bowl) and then plug the drain-screw hole with your finger while spraying the Gumout. Spray it for a while. You need to fill up the float-bowl and then have it continue to "reverse flow" up through the carb needle. I kept going until the Gumout was dripping out of the air- cleaner. So far (and it's been a few months), the problem hasn't returned, even after the bike sites for a couple of weeks. Hope this helps.


In an analogous case, I removed and cleaned the carbs on my Honda Rebel just recently, thinking I had done a pretty good job. In fact, it was kind of half-ass, since I tried to cut corners by spraying carb cleaner and soaking only the obvious parts. I then added a couple of good solid glugs of Duralube gas treatment in the tank. What I did was just make things worse. My efforts ended up loosening up gunk from the tank and the carb's interior nooks and crannies and sent that stuff into the tiny jet holes. I could only keep the bike running at high revs. Both the pilot jet, and slow jet clogged up with so much unanticipated flakes of crap that it would not idle at all. The main jet was OK (there are 3 jet systems on the Rebel). I think because the hole is much larger. Thus explaining why it would only stay alive at higher revs. I took the carb off and did the thorough cleaning I should have to begin with. I went so far as to inspect everything with a magnifying glass. The Little Be-atch, as I so affectionately call her, runs like a top now. Good luck and let us know how it goes.


That definitely sounds like a stuck float. There may be some debris stuck in the seat of the valve. That's what happened to me and my bike did exactly what you're talking about. Pulling the carbs can be a pain in the ass, but if you take you're time you can do it.


Has this bike been sitting without running for an extended period of time? Seafoam is a fuel additive, not a carb cleaner. If you are going to go to the trouble of rebuilding the carbs, they need to be soaked in carb cleaner. Contrary to the other answers I know you'll get from this forum, if you don't know what you are doing, just take it to the dealer. If you do try to do it yourself, carb cleaner and a clean(dry) compressed air source are essential for success. You will hear of many shortcuts, whether you take them or not depends on how reliable you want the bike to be. The dealer can do this job in a couple of hours. Sure it'll cost you, but you drop off a bike that runs like garbage, and pick up a bike that runs like new. Let the opinions begin. Freak
I'll have to along with that. Given that there are many very talented and ambitious individuals in this group, there will be many exceptions to this advice... I am fortunate to have a very good & trusted wrench to go to, an independent and also a Kawasaki fan himself.

When I took my 750 in last fall for new tires, we talked about maintenance issues. While there are many things we can (and should) do for ourselves, one area he specifically cautioned that should be left to the experts is carb rebuilding. It's a complicated area with many ways to get it wrong. So take this FWIW, but unless you really know what you are doing or are prepared and willing to learn a lot, taking this one in for service is is not such a bad idea. -Tim S. <Minneapolis>

If you choose to do it yourself it is not that difficult... If you will be tearing the entire thing down then you will need to order some of the small cotter pins that hold some of the levers together. Before you soak the parts in carb cleaner make sure that no rubber parts are being soaked too, it can cause the rubber to seal bad and weaken the rubber. As far as messing up the "timing" of the carbs or synch, you will need to synch the carbs after taking them apart. Synching the carbs requires a mercury gauge that attaches to the two vaccum nipples on the carbs and a 7mm box end wrench to adjust the synch screw. It is a bit overwhelming the first time but after you have done it once it is very easy to do it again. I will add thought that on a stock 750 the carbs can be a pain to get out with the stock air box still attached. I have doen the ear shave and coastered my bike so it is really easy for me to remove my carbs. Good luck! John R. Auten

Q: II have a new Vulcan 750. It seems like there is excessive play in the drivetrain. It feels like the damper pad in the rear drum is missing. It is most noticable in first and second gear. Does anyone else feel this jerkiness (or is it just me)?
A: Two things come to mind...actually, three.

1. The vent hose fromt the tee over the carbs to the back of the right ear (air filter housing) may be bottoming out. Pull it back slightly; better yet, cut it off at a 45 angle, so it can't shut off the vent.

2. The tank vent under the cap may be closing off, or the tank vent tube is stopping up. The vent in the cap itself is very tiny, and it doesn't take much. BTW, that tiny vent benefits from being drilled out with the next size up wire guage bit. Take the cap apart before you drill it, tho! ;-)

3. The most likely one--trash in the carb needle seats. Take the drain plug out of the bottom of each carb and let the fuel drain out, then use the little red spray tube with a can of Gumout to load the float bowl with it, holding a finger over the drain plug hole, and spraying up thru the drain hole. Flood the float bowl with the Gumout, then remove the spray tube and your finger. Couple of times with each carb oughta do it. It's easier to tell when the bowl is flooded if you pull the vent hose out of the right ear and let it dangle out the side; Gumout will come out the tube when it's full. Replace the drain plug, leaving it slightly open, put the vent tube back in the right ear, put the tank back on, turn the petcock to Off 'til fuel starts coming out the drain, and close the drain plugs. Turn the petcock on, fire up the bike, and see how she runs then. hth Jim
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