thick smoke

[peeps]

A friend of mine just got his 400ex rebuilt, and now if he revs it to wot at idle it blows a thick puff of black smoke out of the exaust. only mods are the pc slip on, any ideas? mabey something with the jetting?

[Pappy]

If it puffs then immediatley clears out, a guess would be that he is rich and its carbon build up in the exhaust

[redexrider]

I am not positive on this but when you get it rebuilt, don't the rings need to fully seat? so you might get a little oil in the cylinder, and it will burn black? Like I said not positive, but it sounds like oil to me.

[miller821]

Originally posted by redexrider
I am not positive on this but when you get it rebuilt, don't the rings need to fully seat? so you might get a little oil in the cylinder, and it will burn black? Like I said not positive, but it sounds like oil to me.

Usually when its oil its blue/whitish colored.

[redexrider]

yea good point I guess that is what a two stroke spits out huh... my bad. Thanks for the heads up though.

[Rider-trx_250ex]

Originally posted by Pappy
If it puffs then immediatley clears out, a guess would be that he is rich and its carbon build up in the exhaust

yup, that happened on my 250ex