I have a Kawasaki Bayou 300 4x4 [1993]. It keeps getting carbon on the plugs. It only takes 1 hr of running for the bike to start hesitating, backfiring etc. It will start and idle find. But when you try to accelerate it does this. I clean the plug and it will run find for a short while. I changed the carburator. I tried adjusting the air/fuel mixture screw thinking it running too rich. This has not helped. The air filter and plugs have been changed. I got this bike from my father for my son. I know that the valves have never been adjustied. Could this be the problem? All help would be appreciated.

 

Clymers says the valves should be adjusted every '90 days of service'. So if you've ridden the thing for a full 90 days worth, then maybe it's time to adjust the valves!? I know that rich problems can be caused by the carb, wrong spark plug, low compression, or even timing issues. Sounds more like a valve problem though. Here's my books specs for the valves:
COLD: Intake-.10-.15mm
Exhaust- .15-.20mm
Good luck man

 

Thanks for the valve information Matstang. I'm going to try adjusting them when I go to hunting camp in 2 weeks. I forgot to mention that there is a hole in the airbox. Can this cause any problems?

 

Really I don't think it would cause a short term running problem. I could see in the long run it causing issues, so if you can figure a way to close it up that would be good. I guess it really depends on how big the hole is!

 

Tight valves problem would typically give hard starting even when hot AND stalling problem when coming to a stop not carbon on plug problem.

If your 300 doesn't have above 2 symptoms, it's not the tight valves. But it's a good idea to check/adjust anyway to save your cyl head from getting hammered by tight valves. But don't be surprised if that does not solve your problem.

Since you defitnitely have rich running condition, I would check the choke system on your 300. The plugner at the carb might be hanging open allowing extra fuel to the carb (that is the choke system which is actually a fuel enrichening device), causing engine to run too rich. Also, excessive carbon on plug means, piston, valve seat area on the head, every where else inside combustion chamber except cyl wall is probably gunked up with carbon deposits. It's best to open it up and clean. If that's too much work you think, run some carbon removing fluid in fuel tank and/or directly spray into the carb throat while running the engine. That should bring up the lost performance of the engine.

 

What carbon removal fluid should I use to remove carbon deposits from valves etc. ?