Its a thunder tiger MKII trainer that was purchased about 5-6 years ago and has been in the box up until about 2 months ago.

there is no play side to side and it sounds good and runs well. Its only got a gallon and a half through it, and I've made sure my props are properly balanced.

Campgems - I forgot that it's a bushing motor. Thanks for the reminder. I suppose it is what it is, as you pointed out. If it gets super bad ill just get a new crankcase and a gasket set.

Do you think it would help reduce the blow-by if I used a thrust washer that is .001"-.002" thicker?

Thanks,
Jeremy