Can taking out Power Valve and Changing Ignition Coil convert Senior to Junior Rotax

A local trader at my circuit is selling a senior engine with a evo barrel and i was wondering if i could remove the power valve and swap over my junior ignition coil and it would become a Junior Rotax Engine.


I’m guessing no. Think there are different cylinders for senior and junior motors.

Do junior barrels have the power valve closed off?

Don’t think that one is machined into a jr cylinder. The barrels have separate part numbers. I see kits to update a jr motor to a senior, but not the other way around.

No, you cannot do that. The Senior cylinder has a slot machined above the exhaust port for the power valve, and the port timing and dimensions are different than the Junior cylinder.

1 Like

Christian is right, the junior is a totally different cylinder with the PV port sealed off