I thought I did all the research - I read all the threads I could find, I got instructions from Thumperfaq.com, I printed pages from my shop manual, but I'm still stumped with the YZ timing. Keep in mind I'm a weekend mechanic only - this is probably one of the most complicated things I've done with an engine. Laugh if you will . . . Anyway, I got to the step of removing the timing chain tensioner - removed. then I realized the flywheels did not have the little puchmark at the top of them and the E was upside down on the right side and the I on the left. I had aligned the H symbol in the sight window and thought I was at TDC, but apparently I was at the top of the compression stroke, not the top of the exhaust stroke. SO without reinstalling the timing chain tensioner I rotated the engine trying to get it to the top of the exhaust stroke. Did I screw up the timing or is that only if I rotate the engine after removing the cam tower? The reason I ask is that after finding TDC (as I thought) the exhaust cam has the little punchmark at the top but the intake cam has it at about 3 o'clock. Do I have to re-time from scratch? If not, how do I get both sprockets to have the punch marks on the top? Do I just keep rotating until they line up? I really appreciate your help. Maybe I have to find a mechanic who does house calls, but I'd rather be embarrassed in front of a computer screen than with a guy who looks at me like I'm some dumbazz which I guess I might be.