When Yamaha produced its first two-strokes, engineers surely encountered this problem, which explains why they tended to locate wrist pins quite low in their pistons, farther away from the very hot piston crown. In early models, this was evidently workable, for when I took after-hours work at a Yamaha dealer in 1966, rebuilding twins crankshafts for $10 apiece, I was fascinated by one of my first rebuilds, a twin whose con-rods were unusual. First, their oval beams did not have the normal I-beam cross-section. Second, their small-end bearings, through which the wrist pins pass, were plain bronze bushings. This engine may have belonged to a US serviceman who had brought it back himself from Japan. I never saw another like it.