Most common sizes 53, 71, 92 and 110, all Cu In per cyl, no matter V or L(inline), whether turbo supercharged(T) or just blower natural aspirated. I worked on these for over fifteen years with tools in my box I will probably never handle save to move around again. As stated all 2 cycles, dubbed as 'Double Breasted Yamahas', or Drip-Troits. The engines had simple drawbacks, as the engine wore it developed blowby, that also equated to blower box slobber so the engines had designed in blower air box(engine block) slop drains, when the engines ran these would steady dribble to the ground, plug those and a runaway was inevitable as the raw oil filled the airbox. The engines had a harmonic vibration due to the fast firing rate, that would back off every cover bolt on them and inevitable leaks would prevail, if piston wrist pin seals failed excess crankcase pressure would flow oil to the surrounding area, trailer nose, engine compartment, ground or road, have witnessed that many times in my days.