2004 CRF 250R Valve Adjustment

I picked this bike up on Friday from my friend Mark.  It’s his nephew’s bike that he recently purchased.  Lately it has become difficult to start.  We suspected the valve shims are getting tight, so I offered to check it out for him.

Here it is prior to any work:

My girlfriend Sara likes to turn a wrench too!  I am fortunate to have someone who fully supports and helps me fulfill my hobbies.

Finding top dead center:

And here we are with the problem.  The intake valves only have .0025″ of clearance.  The recommended clearance is .005″ plus or minus 1 thousandth.  The exhaust valves had .006″ and .005″ of clearance.  Recommended is .011″

At this point, you can just pop in new valve shims from a kit, but to save the customer money, I ground/sanded the existing shims down using a piece of glass as a flat surface and 200 grit wet/dry sandpaper for the initial sand and then finishing off with a 500 grit for the final sanding.  I use larger sheets and run in a figure 8 pattern until I have achieved the desired thickness.  In this case, I removed .0025″ from each intake shim and .005″ and .006″ respectively from the exhaust shims.  To accurately measure this I use a micrometer and measure the shim prior to sanding, then adjust the micrometer for the desired amount removed and lock it.  Keep sanding until the shim fits into the micrometer.  Then you have successfully adjusted your valves without buying a $79.99 shim kit!

Author: joedean

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