Engine noise

Joined
Apr 10, 2007
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#1
I Just purshased a 1982 yz 250.The bike is like new.I seen 2002s in worse shape.I will have pics later.The trouble im having is.When you rev the engine,and when the engine is coming down on its revs,you can hear a very loud rattling noise.I have been away from dirt bikes for a longtime.so need a refresher lol.any help would be great.
 
Joined
Mar 30, 2006
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#2
Mine pops a bit when you rev it high and the revs are coming back down but it doesnt rattle. Take your magneto cover off and see if you can move the flywheel at all. If it moves then you need new main bearings and quick. I know personally what happens if you don't. Also it probably needs a new topend the piston could be worn excessively and causing piston slap.