Jim, this seems unusual...I just took the back plate off my 50SX the other day and I was shocked at how BRIGHT it was inside (I also use Wildcat/Hobbytown...10%...cas/syn w/ extra oil added to get up to 20%). About a year ago I installed high speed high heat bearings, so no rust.??....Dave


I will hold off re-assembling the engine until I am convinced I have it correct -- this is a fantastic running engine and the only complaint I had was how quickly it became varnished-up.