No Compression--Out of Time??

[dirtstalker]

I finally got around to tearing into the top end on my bro's 400ex. It lost compression a while back, figured it was a blown pistion and or rings. After getting it apart today, piston is fine not a bad spot on it. Rings all move freely, none froze up. Valves looked to be seated properly. The rubber o-ring between sleeve and sleeve cylinder was broke in one spot but was still together. Would this thing being out of time make it loose compression? I'm at a loss on this one lol..

 

[Gen1Pat]

Yes it can. If a valve is partially open when the piston is at TDC of compression stroke.

 

[dirtstalker]

okay thanks. Guess since it's already tore apart i'll freshen up the top end. New valves and seals and new timing chain for sure. Like just a few parts to install on the warrior and i'll be ready to ride. Then gotta put the ol' honda back together before the warm weather gets here.

 

[Gen1Pat]

That's what I would do.