New to forum. Just purchased bike w/42K miles and checked compression. Compression was 180 front and 165 rear. Then I set the valve clearances to spec. (7 out of 8 were off. The front intakes had NO clearance. Others were off. Some off big.) So after shimming to spec all the valves, I did another compression test. I got 140 and 140! How could this be? FYI: Bike was cold both times, throttle open, and used the same compression tester. Do valve clearances affect compression like that?