Motorcycle Repair/honda cr 450


thanks ws for reply , coolant / oil ok , spark plug out but engine still wont turn , tried putting in gear and pushing it but wheel locked. no noises from it when it was running , someone told me the piston should be changed every 15 hours run time this has never been done . thanks

Hi Jim,

If the engine did overheat or the head gasket
leaked coolant into the combustion chamber
it may have seized the piston in the cylinder.
If it won't turn by hand or by pushing it in gear
then it must be locked up pretty bad.

You could try to work some oil into it through the
spark plug hole but it sounds like you will have to
remove the head to see what's wrong.

You will have to check the piston, rings and
head gasket. Also the connecting rod should be
checked to make sure it is not bent.

You will want to flush the engine out and make
sure it is pumping oil if you rebuild it. Check that
the head surface is flat and if the bike was running
lean or hot you may need to rejet to a larger main jet
in the carb.


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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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