Oil leak around cylinder stud bolt

[Jenkin]

Hi all -

I have a significant oil leak around the cylinder stud bolt nearest the spark plug. Oil is pumping up around it.

My initial thought was a head gasket failure/leak, but when taking things apart, the head gasket is in fine shape and clearly has been replaced recently. The stud bolt in question is badly discolored and oily while the others are very clean and shiny. This leak has been going on for awhile. Taking things apart further the cylinder gasket itself is most likely original (this is a 2000 model) and exceptionally brittle and flakes off in chunks except where it appears fused to the block.

Is it probable that the failed cylinder gasket is the source of the leak? Any other thoughts before I dig deeper? The cycle runs great just leaks oil pretty badly.

Thanks.

[motorandy]

Just within the last week I've torn mine down also. I have (still) a leak at the base of the cylinder. I bought a new cylinder and piston kit from eBay. The parts were perfect. Installed the new gaskets and buttoned everything up. Now after riding for a few days, the leak has reappeared. Friends think the case may have warped. I've ordered new gaskets and will tear it down again. This time I'm going to add Permatex Copper high heat RTV to the base gasket and see if that will help. And I'll check the case with a straight edge as well.

So my suggestion might be to see if the sealing surfaces are truly flat. If not, you might find a machine shop that will mill it. Or add some type of sealant (high heat of course).

Good luck, and let us know how you make out.

[motorandy]

Oh, one other thing I tried. I was suspecting the crankcase ventilation. So I removed the short piece of hose. Bought about 2' of hose and a clamp. I installed the hose and clamp and ran the hose up high near the seat. Still leaked...

A word to the wise.