Well, it's a bit of a simplification. Anyway it's a damn sight easier to make a four-stroke with a broad range of useful power than it is a two-stroke (and a Wa

Well, it's a bit of a simplification. Anyway it's a damn sight easier to make a four-stroke with a broad range of useful power than it is a two-stroke (and a Wankel is just a special case of two-stroke), without getting into stuff like YPVS and stuff. They're fiddly to make in that they require really weirdass machining techniques and interesting materials for the seals, which are not yet something we've worked out how to do.