Rebuilt engine smoking

[atb7346]

I just rebuilt my 400ex with a 416 kit. I think I may be a little to worried. How long does it take for it to stop smoking after rebuild. Also, I hear a new noise that almost sounds like the rings moving up and down, but I am not sure. It is still smoking like a chimney. Please advise.

[88blaster]

its not uncommon for a rebuild to smoke a little and make a bit more noise, put a couple of easy hours on it and it should stop both, if not, then, you can worry

[enduro400rider]

did you have the head rebuilt? sometimes if the valve guids or seats arnt good, oil will leak into the cylinder while its sitting and then burn off once you start it

[atb7346]

I replaced the valve stem seals, so I don't think it is coming in thru the head.

[GPracer2500]

Still smoking?

Could be the rings were installed wrong or the cylinder was not bored and honed correctly.

[atb7346]

I haven't got to run it good yet. I don't think it was bored and honed incorrectly. That was done by a qualified porfessional. I installed the rings and I made sure to stagger them. I am hoping ti jsut needs a good break in.

[400exrider707]

Originally posted by atb7346
I haven't got to run it good yet. I don't think it was bored and honed incorrectly. That was done by a qualified porfessional. I installed the rings and I made sure to stagger them. I am hoping ti jsut needs a good break in.

I had a problem similar when I rebuilt my 400ex. I did everything good, it had great power, ran like a top started good, never any signs of lost oil, but it always puffed a little on startup, and when I got on the gas really hard. Never figured it out, didn't really care, just ran it!:cool:

[mgraff400ex]

when you put it back together did you check ring end gap before installing the rings on the piston. it's something easily forgotten but would save you a lot of heart ache if the guy who punched the hole made it a little tto big

[Bigbadfords]

If I were you I honestly wouldnt worry about it as long as it runs and starts up fine. My 400ex is an '05 and it does the same thing, smokes on startup and also when I really get on the throttle it will puff some smoke out.