my 300ex smokes when revved

[northy]

i just had a top end rebuild and noticed that when i rev my quad ( in neutral or when excelerating) a bluish, black smoke comes out. it only happens at about 3/4 throttle and above. There is also alot of carbon buildup inside my supertrapp pipe. Any ideas, All help would be appreciated.

[future 450?]

that happened for a lil while when i had stock pipes on idk y though

[rooster300ex]

Your air/fuel mixture could be rich with to much fuel. there is alot of people on here that know alot about proper jetting. Oh yea does the smoke smell like oil burning or a real fuelie smell.

[2004exrider]

sounds to me like your running to rich on your main jet. the main kicks in at 3/4 to w.o. throttle. does it bog or pop when you give it full throttle (not in nuetral but when riding)? check the spark plug for the proper jetting.
BLACK- rich
GRAY-TAN- perfect
WHITE- lean

Jimmy

[JRP]

Originally posted by 2004exrider
sounds to me like your running to rich on your main jet. the main kicks in at 3/4 to w.o. throttle. does it bog or pop when you give it full throttle (not in nuetral but when riding)? check the spark plug for the proper jetting.
BLACK- rich
GRAY-TAN- perfect
WHITE- lean

Jimmy

yep do that procedure to see whats wrong.

[northy]

thanks i'll try those suggestions

[dsheola]

check your jetting
black smoke is fuel
whiteish blue is oil which would mean your cylinder wasnt honed properly or at all and oil is passing your rings. The guy who did my motor neglected to hone the cylinder after he bored it so oil blew through at around 8-9,000rpm wasting my JE piston clogging my valves and causing a pain in my ***. I had to rehone my cylinder and get a new piston and all.
Hopefully for you its just black fuel smoke.