>2 cycles are lighter, more power efficient, having a power stroke each time
>the piston rises.  No crankcase+no oil changes, less moving parts.

Yuk. Twostroke. Pemix. Stink.

Actually, it is possible to build a fourstroke-based twostroke.
Toyota designed & built a DOHC 2-stroke (I have seen photographs).
The cams run at crank speed. Zero valve-overlap, of course. With
variable valve timing this could be the ultimate 2-stroke. And no oil
in the gas! But I doubt it will ever reach production, as it was made
years ago.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
<andrew.grebneff@stonebow.otago.ac.nz>
Seashell, Macintosh, VW/Toyota van nut