Back on this project again.
This was acquired not running and very cheap as a result. I have cleaned it up, did some
Engine CSI to determine no compression and some mechanical lockup inside, took the Engine out and top end off. Piston has several pieces broken off edge in one spot. Rings and cylinder substantially destroyed of course. I have the cylinder off of the case, and have thoroughly cleaned all small pieces out of the case. I don't think it was ran like this but for a second. I was able to contact the previous owner and he said he was riding it and the wheels locked up, he skid to a stop and it never ran again. The biggest chunk of piston was wedged in between the case and the crank weight section, causing the lockup spot. No visible damage in lower end that I can see. I have rinsed it all out well. All gears mesh correctly, no broken teeth, timing gears and chain all seem ok, rod still connected to crank has a very very little bit of side to side play, crank is rotating smoothly and no play can be felt in any axis, crank oil seals were not leaking, nothing seems sloppy anywhere. The edge of the inside of cylinder head, adjacent the intake valves does look like the piston pieces hit it on an up stroke and slightly mushroomed it there inside the cylinder. I noticed the head bolt alignment dowels (knock tubes) looked slightly bent. The valves don't look bad but I don't know how to check if they are bent, and if they are seating and sealing? The cam has no excessive wear, rockers look ok. No missing parts that I can tell.
I now have on hand 2 new alignment dowels, a new cylinder, piston, rings, and gaskets. My question, before I put this stuff back together... I am leaning towards taking my chances with the lower end, it just looks all ok to me but would you recommend I do anything with this head? How can I test it or is that strictly a machine shop service? Do you recommend a particular machine shop? Do any of you do this work? I think the service manual has some sort of cyl head leak down bench test... have you ever done this? What about the mushroomed area in the aluminum? I can get new valves and springs on ebay for another $160 investment but I have never lapped valves before, and even if I do that I have the small mushroomed section.
That's a lot of questions.. sorry. I do appreciate any advice.
Many thanks!