Freshly rebuilt 2010 YZ450,oem piston and gasket set used. After running the bike initially noticed coolant “weeping” from the base gasket, particularly on the right side and front of the cylinder. Took the bike back to the mechanic and had him install a new head and base gasket. He said both the cylinder and case surfaces looked fine, as well as the olD base gasket. He started the bike several times, I have not since getting it back. It sat for a couple days in the garage and is now weeping again, same spots. It’s not pouring out, but enough to make a small pool behind the cylinder on top of the cases, and clearly is damp along the right side of cylinder. Can I assume the cylinder is warped at this point? I didn’t ask but assume he did not check to see if it was warped. I also did not ask if he used the technique in the manual for torquing the bolts(ft lbs reading and then further torquing by angle, can’t think of the specific number values off the top of my head). Any other reason it would be weeping at this location? Haven’t had the chance to drop the oil yet, but it didn’t look milky in the sight glass when I picked it up. Thank you
Highly unlikely that the cylinder is warped. May have been machined incorrectly but why didn’t it leak before? I would take it back to the dealer since you paid for the work. I would ask if he used OEM gaskets. If you decide to tackle it yourself, place cylinder on a glass plate and use feeler gauges to see if there are variations. Also check for coolant in the oil. Good luck.
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