I checked my valve clearances. YZ250F manual said between .10 - .15 for intake, .17 - .22 for exhaust. Intake was less than .002 in (.002 wouldnt fit in there), so its either touching or its .001in. Exhaust is .006in. But heres the tricky part: I checked my intake shims and they are all 1.35mm. After doing the calculations, which I am sure I did correctly, the intake shims come out to be needing a 1.20mm if the intake is 0.001. According to the calculations, that should bring the clearance back to 0.006in. That will do. However, 1.20 mm is the smallest size shim they make it seems. What happens if I need something less than that? Dont valves tighten over time?