The TZR was the aluminum framed 250cc successor to the RZ350. Barrels are separate casting with a powervalve that connects between the two and is very similar to the RZ350 set up. The cylinder head is a one piece unit for both cylinders so it would need to be cut in two to fit a scooter.

Some issues involved in adapting this to a scooter are that the powervalve actuator is on the right hand side of the barrel which would be problematic for a Vespa. Maybe it could be mounted to have the exhaust exiting toward the rear of the scooter which would make the powervalve actuator stick out to the right. Also the watercooling comes off the crankcase without a separate barrel intake as far as I can see (see the latge oval hole in the gasket face just under the exhaust). Intake would have to be through the crankcase as there is no barrel mounted intake.

The 50mm stroke is very close to a small frame stroke so with some adaption it could work.

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