Strange KX250 fouling problem

[kzuby]

I fouled 2 BR8EX plugs on my 96 KX250 in about an hour of riding. (The second plug-after I stalled the bike for a short break and restarted it, took off and just died while at about 1/2 throttle) The bike ran great for the longest time until now. It has a pretty recent top end and the only thing I did to it before riding was throw in a new filter. Is it possible to over oil the filter and foul the plug? I use FAB-1 spray (the blue stuff) and oiled it just a little more than average due to the lack of rain and lots of dust. The bike has been jetted and tuned from the guy I bought it from. He used to race it. I am also considering to raise the clip 1 notch (lower the pin) on the carb because the cylinder seems to load up pretty fast while cruising in low RPM's. Even when I grab the clutch and rev it every once in a while. It takes a good open trail and a few good cranks on the throttle to clean it out. Never had a prob with the plug until now, though. I do all trail riding. I mix synthetic 32-1. Already checked the carb and it's clean. Any thoughts or suggestions?

 

[kawamaha]

generally a fouled plug means rich jetting. if your filter is overoiled there is less air coming throug it, means richer mixture.
you can try to lean out the pilot one or two sizes and lower the needle (raise the clip) one notch. if you rev the engine mostly low to mid you can also try a hotter BR7ES plug.
and, for testing use a BR8ES / BR7ES instead of a BR8EX - the ES are much cheaper...

http://www.supercross-online.de/e/

 

[YZThumper]

Do a leak down test. Fouling plugs can also be caused by a leaking right crank seal. Oil gets past the seal and sucked up in to the cylinder. Had this happen to a YZ250 I owned. Spent hours chasing my tail on jetting changes, only to learn the crank seals were shot.