Took the top end off the motor and noticed on the bottom of the barrels where the piston liner sticks out from the bottom of the barrels their is a rubber seal around the liner and fits into the bottom of the barrels but cannot see what it does , anyone know :unsure:
Yamaha genesis 750 , No its not a seal for water or anything else as I can see , if you look at the cylinder next to it you can see where I have taken the seal out, but its not sealing anything at all . :wacky:
I'm on you bench. The water jacket is going to be higher pressure than the crank case The base gasket may allow seepage of the coolant. The o-ring would not. That's my best guess. As the oil feed to the head is probably higher than the coolant pressure, the o-ring is probably not needed.
Yeah you are right in what you have said about the oil and crank case pressure , and I agree on the O ring bit as well , it may just be there as a back up like you said against seepage from the outer cylinder sleeve due to possible expansion and contraction .
Another purpose this seal may serve is as a damper, due to the extension of the liners from the barrels. But as they are dry liners it is most likely to be a seal to prevent coolant escaping between the barrel and liner which can cause problems.
