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Engine rebuild on 06 YZ250F


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I own a 2006 YZ250F and currently it has 88 hours on the motor (total), so I`m going to tear it down. About 80% of those hours were logged in the woods. I change the oil and clean the air filter every 6 hours. I typically don`t rev my bike out as I`m only 130 lbs. My question is should I replace the crankshaft? I`m not really sure if it is necessary, but I would like a second (or tenth) opinion. Thanks

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88 hours on the current build, or 88 hours total run time on the engine.... 06?

Check the teeth on the small end of the crank.  Profile in the teeth should not be sharp and pointed.  If they are, replace the crank and rod assy.

Check the rod large end play.  The rod has a spec for clearance between the crank webs.  It should not lean over.  If it does, replace the crank and rod assy.

Put a new piston pin into the rod small end.  Try to rock it back and forth/up and down.  If there is any play, replace the crank and rod assy.

Those are my checks.

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7 hours ago, ronbuell said:

88 hours on the current build, or 88 hours total run time on the engine.... 06?

Check the teeth on the small end of the crank.  Profile in the teeth should not be sharp and pointed.  If they are, replace the crank and rod assy.

Check the rod large end play.  The rod has a spec for clearance between the crank webs.  It should not lean over.  If it does, replace the crank and rod assy.

Put a new piston pin into the rod small end.  Try to rock it back and forth/up and down.  If there is any play, replace the crank and rod assy.

Those are my checks.

88 hours on the engine, total run time. I purchased it last year because it was barely ridden.

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I rebuilt my crf250x after 200 hours of me riding it with unknown hours before me and it never had the had off. I rev it quite a bit but not rev limiter and cylinder was in spec and looked new and crank was good. ended up putting a stroker crank in it for peace of mind but it lasted really well. I would put a new piston in in it and check everything over and go another 80 hours

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88hrs it will be fine as long as you are accurate. If its woods only and not worked hard the piston and rings will do 100hrs. Check the valves to make sure the clearance is ok if so ride it to 100. Then do the top end piston rings etc etc make sure you do a timing chain every piston. This engine well maintained and woods ridden will do 200 plus hours on the bottom end easy. 

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