650/X-2 650sx makes low compression

hemiorange650

hemiorange650

Location
las vegas
so my 650sx makes 105 psi on a compression test has no balls when its on the water. i pulled my my cylinder off and and the piston, cylinder walls and rings look fine. so i was thinking if i put new bore pistons and rings would that help? or maybe even just put new rings?:pancake::pancake:
 
dbattersby20

dbattersby20

Location
New Jersey
If the motor is clean (no large scratches along the walls, and the piston has no chips in) then I think it would most likely be the head gasket. I would try replacing the gasket and test it out. My 650 has some wear to it and the motor isn't too clean, but still gets a little better than 145 compression.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
Only takes 1 score of the piston wall to kill the compression. I'd replace the head gasket. If compression stays low then hone and replace the rings.

Boring it is a preferance if you think you want more power (which is a poor dollar for dollar investment in power) or if the walls are too damaged to hone.

Either way you need a new head gasket. If you do decide to do something to the top end (hone, bore, w/e), take it apart before you buy the top end parts and inspect the bottom end for excessive play, w/e. (not likely a bottom end issue would cause compression issues but it's a good time to check fir wear)
 
hemiorange650

hemiorange650

Location
las vegas
ihave it fullly takin apart and the motor is cleaner then ever i mean its clean! the head has no corrosion on it. but yeah the walls look great im gonna hone it anyways thanks for the info
 
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