Why Does My Kawasaki Motorcycle Spark Plug Keep Fouling?

If you have an older model Kawasaki motorcycle like the KD100, that keeps fouling up new spark plugs after every couple of rides, could the bike be running too rich?

Partzilla’s Kawasaki motorcycle expert John Talley hosts live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this session, John was asked what could be causing a 1978 Kawasaki KD100 to keep fouling up its spark plugs. 

Kawasaki Motorcycle Fouled Spark Plug Q&A

Hi, I have a 1978 Kawasaki KD100 and it runs awesome, but every couple of runs, it fouls the spark plug even though it has the right spark plug in it. Any thoughts?

John Talley: That’s a two-stroke, isn’t it? I’m pretty sure the KD is a two-stroke, but anyway it sounds like she’s running way too rich. So it may be time to back off on the air-fuel on the carburetor a little bit. The only other things is, well I can’t remember if that has an oil injection system on it. I’m old enough, I should remember, but make sure that isn’t oversaturating the oil-to-fuel ratio. I think that one’s at like 32:1, if I remember correctly. So take a look at those two things first. If both of those things are right and she’s still fouling plugs, maybe go to a little bit warmer plug, whichever one that would be in the NGK range. 

Watch the video below to learn how to test the spark plug on a Kawasaki motorcycle.

Watch the video below to learn about the basics of cleaning, rebuilding and replacing motorcycle carburetors. 

Watch the video below to learn how to do a leak down test on a motorcycle.   

Want to see more live repair questions answered? See more motorcycle and ATV repair questions answered here.