400ex smoking when i push throttle

[sprt400ex]

my 400ex smokes when i push the throttle. its blue smoke. it idles fine and after the engine is warm it doesnt smoke anymore.
please help me find the problem. thanks

Is there enough oil or is it the right kind?

[Guy400]

I'm not going to say that there's nothing wrong but there's MANY other 400EX owners talk of the same problem. Sounds like an issue with cylinder clearance in relation to your rings. When the motor is cold the rings contract a little, increasing the gap between the rings and cylinder walls and causing a little blow by. When the motor heats up the rings expand, sealing the gap.

[sprt400ex]

yes i have read that, and i have to say this problem has only been happening since its bee getting cold if that has anything to do with it.
thanks

mine didn't do it till this summer so i figured time for a new piston rings and bore job..due to what what guy said

[schism_rhs]

my bike does that , on mine its just leakey valvue seals !...right when it warms up it goes away completley !

[sprt400ex]

so should we not worry about it or what?

[schism_rhs]

I wouldn't panic over it, but if it has gottin alot worse since it started or looks like its getting worse, I'd get it checked out...

not trying to say it's not leaking valve seal but in most cases the smoke happens when to piston and rings have worn...due to more space now between the piston rings and cylinder wall(due to the wear) it takes longer for the piston to heat up and swell to seal better which allows oil to get by between start up and the time the piston and rings swell to seal up the gap..it's no real big problem but sooner or later the engine will need a new top end