ORIGINAL: mike109
I have a Saito 120 that was owned by a friend and given to me in bits. He had run it lean on fuel with synthetic oil only (I always use some castor in my fuel) and he had destroyed it internally. It looked OK on the outside but the bore is scored, the ring has gone soft from being overheated and the bearings were a mess of rust. It is not worth repairing.
I've built/rebuilt alot of engines and maybe the costs are too high... but wouldn't a hone job , rings, and a couple bearings do it wonders? I imagine these little engines run real hot realtive to conventional water cooled non-model units. Maybe the tolorances needed cant allow for a slight overbore?