Hey guys,
I need to ask the advice of seasoned 2-stroke owners who may have switched to 4's nowadays.
I friend of mine bought a 1987 yz-125, and has been riding it for a few months now. Not a bad little ripper for its age. Even has an FMF pipe on it (looks nice, not sure what gains it gives the bike).
He had been noticing less and less resistance when kicking the engine over, so I brang it home to my garage to do a compression test on it. I got a reading of just under 55psi, and that took about a dozen kicks.
Also, I find it's really hard to start -- kick and kick, take the plug out and find almost no gas on it. I finally did get it started, but somewhere around 60 kicks (I not kidding).
What should the compression psi's read on a healthy top-end?
What should be replaced? I'm guessing the piston and rings, and probably any gaskets I remove to get at them?
Lastly, should the cylinder be honed before finishing the rebuild? Also, any special instructions on the exhaust valve/port? I took that puppy out of the side of the jug, and wasn't sure if the brass sleeve on the cover plate should have been "stuck" in the spot it was stuck in, or should be able to move freely. I not really up to speed on the 2-stroke engine, but have always been fascinated with their design. I figure this might be a cool thing to learn.
Appreciate any help! Thank you in advance.
-matt