[zixniner]

My 96 ZX-9r fouls a plug once in a while (I haven't really spotted a pattern as to the same plug). I think I warm it up sufficiently before taking off...I live in a relatively cool climate (northern Maine)...is this a common problem? What's the most likely cause?

 

[OmahaRider]

Fouled with what??? gas or oil? I used to have a chart in an old mechanics book that would lead you to the cause depending on how the plug was fouled.

Its been a long time since I've torn into any engines----guess I have to brush up on that again.

It might be an easy fix--like running too lean or rich-----or big problems----like worn out piston rings-----you should be able to tell by looking at the plugs.

 

[shift1313]

refresh my memory

was the 96 zx9 FI? if so the problem is probobly you. If you turn the throttle at all while starting the bike will fould the plugs. Its habit unfortunately. Tls have a huge problem with this.

is the bike stock or does it have some goodies on it?

and definately what is fouling them. Does it foul on start up? does it smell like gas? all these will help

 

[zixniner]

Not fuel injected...black carbon on the electrode...I've been able to salvage the plugs by sandblasting them clean (they're 10 bucks each)...CR9EK, which is the recommended plug for the bike. The bike is stock except for a two-tooth smaller front sprocket. The bike has 5000 miles on it, so I highly doubt it's a ring problem...could un-sync'ed carbs cause this?

 

[shift1313]

i dont think so

depends on if your fouling all the plugs or just a few. id say its an altitude problem maybe or atmospheric . Did you buy the bike locally. You may need to tune the carbs up. you may have to adjust the idle air circuit and give it more air at lower rpms , under 1/4 throttle. this will help on start up but shouldnt affect your 1/4 to WOT performance.

 

[zixniner]

From what I can tell, it's usually just one plug, but I don't think it's the same cylinder all the time (it's happened three times). No, I did not buy it locally, I bought it from my brother-in-law in Rockland, Maine, which is on the coast to the south. I'm landlocked about 300 miles north. Thanks for the info.