I've got a 95 KLX 650C that was super dependable until about two months ago when it started causing trouble. I'll skip right to what it's doing now:
It's extremely picky about mixture when starting cold and it doesn't start easy but I can get it running before the battery dies if I'm lucky. Once it's going I need to make sure it stays above about 1300rpm or it'll die immediately (a little higher than it used to need). If I rev it to 3 or 4000, it's a little slow coming back down to idle and as it warms up it gets more and more reluctant to come down. Once it's fully warm, it won't come down from 3000 at all unless I shut it off and restart it. Then it'll idle fine at 1300, until I rev it again.
It's on it's third plug since the trouble started. All of them fouled with classic symptoms of lean mixture.
It seemed to me like a sticking slide so I pulled the carb and the thing is pristine. The slide moves like silk, jets look perfect, float looks good, everything looks to me exactly like it's supposed to. Cleaned everything up anyway, replaced the plug and air filter, checked that fuel flows from the tank ok, put it all back together, same issues.
The plugs are fouling pretty fast. For a while I was able to drive it before the issue got really bad but now it's pretty much unridable so it's hard to say how many miles it takes to fowl them but I got maybe 100 miles on the second plug.
I thought I had enough ideas to get to the bottom of this but I've run out and still can't find anything wrong. Any suggestions of what to try next would be greatly appreciated.
Edited by apdg, April 24, 2012 - 05:53 PM.