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55HP 2 Stroke Piston

C

c7z06

New member
Hello there

Engine shutted off on me while sailing... the upper cylinder pressure so low, the bottom is fine, i pulled the head out

I found a cracked gasket on the top cylinder, removed it, cleaned the head...

here's pic of the head after cleaning and some sanding.. probably needs more work

image1.jpg



The Piston seems not fine, i can fit my nail inside the area

PHOTO_2018_06_16_13_23_57.jpg


what should i do guys? what you think? should i pull the motor all out? i have rebuild 2 stroke bikes before, but this is my first time rebuilding an outboard...

any advice will be appreciated
 
Piston needs to come out and be replaced. Together with the rings. Cylinder wall honed to clean up any damage. Hopefully it will be within limits after clean up.

Looks like detonation damage to me. Would not be a bad idea to clean the carburetors while you are repairing the motor.
 
boscoe said:
Piston needs to come out and be replaced. Together with the rings. Cylinder wall honed to clean up any damage. Hopefully it will be within limits after clean up.

Looks like detonation damage to me. Would not be a bad idea to clean the carburetors while you are repairing the motor.
Click to expand...

Thank you for your replay

should i change both pistons, is it good idea while the motor is out? or should i change only one and leave the bottom? im concerned about the lower piston it may blow up...
 
I would pull both pistons since when you have one out 90% of the job is done. If the one piston is good reuse it. New rings and hone that cylinder as well as the other cylinder. Which may or may not be damaged.
 
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