MK Star 15 & 60 motor

MK Star 15 designed by Masahiro Kato over 50 years ago is now under construction. As it isn't done from a kit but from pieces of balsa, it takes time and requires much effort. 80 % finished already, but not a few small works remain, I'm sure that it would come in time to next  Old Timer & Golden Age meeting held in coming Spring. For the power source of this model airplane, ENYA 20 with conventional cross flow scavenge would be invited, suitable or less power, probably, in case of poor power for stunt flight, OS 25LA would replace, it depends on the finished weight.

As OS 60 FSR motor appeared in Yahoo Auction I bid only at 520 yen like nothing, actually it was sold as a junk motor. After arriving to me, I knew the reason why it was sold at so lowest price, the carburetor holding screw 3,5mm hole was dead showing at the point in the picture. The former owner had bad habbit to screw in too tight all the screws even on back cover plate. All of them were loosened with heating method. Braking tightening power must have destroyed 3,5mm screw hole. Re-tapping with 4mm tools could recover the problem safe.
Crank shaft supporting front bearing was ill set, rear seal cover had not been removed and original bearing grease was left untouched. He did not understand the physical property of lubrication, just like a layman. It was lucky that the crank bearings on both side, front and rear could be usable after cleaning. Gas compression construction was not damaged.
Any way, it survived as a useful enough motor after full overhaul including carburetor.