Originally Posted by Pigford
STOP - Do NOT bother doing the clearances now
You should redo them AFTER the rebuild, as new head gasket & retorquing the head may well lead to minor distortion & effect the clearance measurement!. ALSO, the clearances are best re-checked with the lobe pointing 180 degrees away from the shim surface - in line with the axis of the valve stems.
The entire valve train is contained within the Head Assembly. So, I'm not sure how gaskets outside the Head Assembly would affect the clearance. This is a new one to me...?? My imagination can follow your idea of some "distortion" a little bit. But, I'm still trying to work this one out in my head....visually. I'm all for learning something new.
Regarding the procedure for checking the clearance, I'll say that I believe I got it right.....at least according to the official Yamaha WR250R/X Service Manual....if that's worth the paper its printed on.
Sometimes maybe they are not.
Page 3-4 "Adjusting The Valve Clearance"
states the following:
Valve clearance adjustment should be made on a cold engine, at room temperature.
When the valve clearance is to be measured or adjusted, the piston must be at Top Dead Center (TDC) on the compression stroke.
Align the TDC mark of generator rotor with mark on rotor cover.
Measure the valve clearance with a thickness gauge.
Out of specification --- Adjust.
So, I'll blame it on the manual first. Then, on the Krabill second. This is same way he taught me to do the KLR motor....same way the KLR manual instructs....and its always seemed to work correctly.
But then, I am no professional mechanic. I probably even break a lot of the mechanic's code....if there is one. But I'm trying hard to do it right. Really, I am. Scout's honor!