Ok...Pulled the whole top end apart last night, and inspected / cleaned everything. Lots of black sticky crud in the powervalves, and everywhere else for that matter. Cylinder looked fine, minimal scoring, piston had a bunch of black crud baked onto the top but scraped right off with my fingernail and some simple green, rings seated nicely, plenty of flex left, After cleaning, new gaskets, and reassembly, it started on the third kick, idled better / smoother than ever, warmed up nicely and seemed totally fine. Better in fact.
No rapping to report yet, but it really didn't do it before until it was hot, and under a heavy low RPM load, so ....just figured I'd give an update. Nothing was broken, just really gummy. Get plenty of brake cleaner, soap and hot water, rags, gasket kit, and go for it! It took me and a buddy 3 hours to do everything. It helps to have another peron there to get the piston back in, but not necessary. I like the fact that you can do most everything with just 8mm and 10mm 12mm 1/4" sockets!! Except the head bolts, a little more tricky to torque properly without that funky 12mm torque wrench adapter tool and a calculator! :thumb:
I'm ready for spring!!! :aj: