82 kz550 carb problems...i think.

So, this is my first post. hopefully i can accurately describe my situation. First some background.

Bought my first bike a month ago. Ran pretty decent when i bought it but a friend suggested i clean the carbs and get familiar with them. Previous owner put after marfet 4-1 exhaust, jetted the carbs, and has pod air filters. Not sure what size, if i had to guess, i'd say its stage one or two.

So, when i first got the bike into my garage it had a terrible time starting. After messing with a few electrical issues. Got it running.

Took the carbs off and "cleaned" them out. I say "cleaned" because it was my first time even touching carbs. I took all the jets out and even took the throttle shaft out and pulled the needles and slides out, really just to look at em. I used degreaser and carb cleaner to wash em out pretty good. Put it all back together and here's the issue:

Bike starts really well but idles up and down all over the place. Once i get it warmed up and idling around 1,000-1,500 rpm, if i give it gas to around 6,000 rpm it will come down and idle around 3,000 rpm. And then some times it will just bump up to 2,000-3,000 with no throttle.

I took it out for a ride to see if i could get a new perspective of the problem. Anytime i stopped at a light and disengaged the clutch, closed throttle, it would still idle at around 4,000 rpm. Each time i stopped it would idle at a different rpm. I found that when coming to a stop if i leave it in gear (6th) while stopping then disengage just before stalling, it will idle where i want it to. I'm not sure what the problem is. Hoping to get a little help. Hopefully this gives you a decent idea of what's going on, sorry if it doesn't. Would appreciate any ideas.

The main causes of this are usually a vacuum leak in the carbs, and/or the timing advancer might be loose or stiff and notreturning to fully idle position. It could be loose if a spring is broken, or if the pivots are corroded it could be stiff.

Are you sure you capped off the vacuum ports on the intake manifolds, and none are left open?


P.S. Thanks Patton

Hello, Matt, and WELCOME to KZr!

Looking forward to your participation in the forum!

Thank you for the welcome! Glad to be a part of the community.

I'm pretty sure there isn't a vacuum leak, i will double check. What is a timing advancer? Where is that located? I'm not sure what you mean by "cap off" the vacuum ports. sorry, still new at this. Thanks.

If the airbox is gone, then most likely the air suction system has been removed or disabled. It had vacuum hoses that went to the intake manifolds. Where those hoses went needs to be capped off.

Do search for vacuum leak and you might find good tips on how to find them and what symptoms they create.

The mechanical timing advancer for the ignition is under the small round cover on the right side of the engine. It is accessed under the timing plate. You need to verify that it operates properly.

There is a manual in my signature if you need one.