KDXRIDER.NET

Well I will start off with some background from my bike. It's a 1996 KDX 200 with a FMF pipe. That's about it. I run klotz R50 at 32:1 with premium pump gas. As far as jetting it has a CEL needle, 155 main, and a 45 pilot. It will run great for a while, with barely any splooge and not much smoke. But, when you try and run it usually the next day or after 4 or 5 hours of riding, it will get to the point where it doesn't want to rev out in 1st or 2nd. It will just start to kind of break up. 3,4,5, & 6th are fine. Eventually it will get to the point where it starts making a metallic noise on deceleration, and will just foul the plug. Also if you try and just hold it in 1st or 2nd past the breaking up point it will foul. What is causing this? It seems to run great with a new plug, at least for the first 4 or 5 hours. Do I need to do a main jet plug chop? I rode it around for probably 2 hours and pulled the plug and there was barely any color on the porcelain!

search and you shall find...
http://kdxrider.net/forums/viewtopic.php?f=77&t=12963

sterlin44 wrote: it will get to the point where it doesn't want to rev out in 1st or 2nd. It will just start to kind of break up. 3,4,5, & 6th are fine.
Eventually it will get to the point where it starts making a metallic noise on deceleration , and will just foul the plug. A

i would stop riding that bike before something really breaks.
i'd say you jetted too fat but only YOU can do the work and find out...

It just seems odd to me for it to run so well but still foul plugs. Most people with stock jetting don't foul plugs and it's extremely rich.