400ex smoking exhaust... not sure of cause and fix

[pimpazzberetta]

Friend of mine has an 02 ex that he purchased and it smokes like a ******* from the exhaust. He tore it down and put new valve seals in, cleaned the valves and seats (which did not look bad at all) Has good compression, new rings also. Besides the valve seals what else could be the cause of this oil getting sucked into the cylinder and burning in the exhaust?

[REDRIDDER]

scratches in the cylinder sleeve or possibly the valve guides are worn letting oil down then and burning it up did you guys check theses 2 things?

[pimpazzberetta]

We checked the cylinder walls as we replaced the rings, however I was unable to get the owner to let me take the head to my work and mic out the valve guides. Just curious though how does oil get past the new valve seals and down the guides?

[JOEX]

What color smoke?
When does it smoke the most? On start up? All the time? Under load?
Did the cylinder get honed before the new rings were installed?

I don't have any real answers, just questions that may help someone else answer:)

[JJE02EX]

Originally posted by JOEX
What color smoke?
When does it smoke the most? On start up? All the time? Under load?
Did the cylinder get honed before the new rings were installed?

I don't have any real answers, just questions that may help someone else answer:)

It does not smoke on start up.. it smokes a lot when reving the engine. Color is white gray, and gets darker almost black when reved hard. The cylinder did not get honed but there was cross hatching in all parts of the cylinder, as it looked to be recently honed before it was purchased a few weeks back.

[Dill]

sounds like overly rich jetting or maybe a stuck float allowing fuel to pour in.

[JOEX]

When I rebuilt mine it has several hundred hours on it yet still had a visible crosshatch. But there is a glaze that forms on the cylinder that needs to be removed so the rings can 'seat' to the cylinder and form a seal.

That's my understanding anyway:p

[1965 honda]

bad ring job. get it done again i just went through this problem.