guys I need some advice,
history of the bike
the bike is a 2001 KX 250
I got it used with very little use on it.
40:1 gas/oil mix, premium pump gas, yamalube R2
sparkplug NGK BR8EG , BR8ES
the bike runs very rich, and dies after some run time. or won't restart after letting it cool down.
the plug it is black but not WET, the reason it dies the spark jumps at the base of the spark plug instead at the electrode.
If I put a new /clean plug it will run just fine for a while.
things I done so far;
repacked, cleaned bafle on the silencer, checked carb jetting stock main is 160 , the bike has a 155 , stock pilot is 52, the bike has a 48 in it.
checked the float level= ok, clean air filter with little or no oil on it.
checked the reed valves , not chiped or dameged.
adjusted the air screw 2 turn out.
the bike runs strong and starts every time on first or second kick(except when the plug gets fouled )
what else there is to check to see why this bike runs so rich?
Cranks seal? , how would you check it wihtout disassemble?