The gas was leaking into oil . I suspect piston ring also metal grinding noise. I'm thinking bad piston . So now i would like to upgrade from china to japan motor . the honda 50 cc looks like a good choice but the 5/8 shaft won't work with my transmision from flying horse so i was looking for some advice as to what to upgrade to . this seems to be a good place to get help.
Bad piston rings and burrs most likely, might be repairable. OEM honda rings and a hone may fix it instead of a new motor. I have one of the ebay 50's and its running pretty good except the muffler fell off.
I did consider fixing piston damage but i just found a striped down motor $ 100.00 from bikeberry . I still want to upgrade but 100.00 gets me back on the road now and gives me time to build the perfect setup. I'll post pics of what went wrong with motor .