Motorcycle with a radial engine, similar to those
used in aviation.

One such bike had a radial engine. I kept thinking that there must be a plane flying around somewhere with a V-twin for a power plant. In this one the engine sat vertically at 90˚to the bike, about the same way it would sit in a plane. It looks like you could just ad a propeller and a pair of wings if you wanted to fly.
But it didn’t take long for other hobbyists to put their own spin on the radial engine concept. I soon found other bikes using radial engines, but with different mounting schemes.

Motorcycle with a radial engine mounted with
the crank shaft transversely.

Another builder must have thought, as I did, that the radial engine looked a little wide. I can just imagine dragging a head in a hard lean. Or worse yet, misjudging a gap. On this bike, they rotated the engine 90˚on the vertical axis. It makes the bike much narrower.
One would suspect that those big radials produce a lot of torque. You’ve got to wonder if that first bike will try to make a left turn if you get on the throttle too hard. And maybe the second one can pop a wheelie with just engine torque.

Radial engine encased in circular cage.

Another bike was built with the same engineering philosophy, but this engine is encased in a circular cage giving the whole thing a very clock-work look.
I’d like to watch somebody ride one of those. I don’t think I’d care to try it myself.

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