When my centre crank seal died, the mixture still burned OK as long as the revs were kept up. It was the part throttle and bottom-end rpm that suffered the most. It still made 60hp though!!

You can check the centre crank seal with the motor in place. Take the barrels off (keep the heads in place to save on gaskets) and mix up some pre-mix at 50:50. Fill the upper (left) side crank case with the pre-mix, and put a drip tray under the lower cylinder. You'll soon see if the seal is buggered!

I imagine there may be a very slight/slow amount of transfer between the cases over an extended time, but if the seal is shot, the level in the top case will drop noticeably in a very short time.

If the seal between the transmission and the crank has gone, it would be given away by white smoke from the RHS exhaust and the transmission oil level dopping as it is burned off.

Oh, and welcome to the Forum!
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Andy.
NSR-WORLD.COM

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