I have a 2005 yz 450. The craftsman feeler gauge I have only goes down to .178 so I am a little ill equipped. The .178 fits under the exhaust valves and the shims are 188, 191 and 189 so I was going to drop down to a 185. This would put me in the .20-.25 spec but the .178 feeler gauge does not go under the front intake valves. The last time I checked them the .203 fit under them. Another issue I am having is the front shims numbers are missing on one valve and it looks like 53 on the other so I am assuming its a 153? Any idea on what came stock on the shims on this bike? I am the original owner and I have never changed the shims. Also I am looking for advice about buying the hot cams shim pak? What is the O.D. of my shims? Do the Honda or Kawasaki shims fit my bike? I think the Hot Cams shim pack would be more cost effective. Thanks for any help.