After spending a year in the BMCA riding pre-65 i deciced to get something that stops(working brakes), bounces(suspension that moves) and weighs less than 100kg.

I bought a Beta 270 from BVM Moto, yes i was getting the 200... . After 2 hours of continous riding i got a loud piston knock at top of travel. 2 Betas i was riding with had no problem. I am using super unleaded and Castrol TTS 50:1.

Have not tried since to see if it happens when cold. Will try today.

Where do i start?? Thanks

I had a tap on my old Beta running 60:1, changed to run 70:1 with Shell Optimax and my tap disappeared.

How can you tell that the knock happens at the top of the piston's travel?

By putting your finger in the spark plug hole of course

50-1 is a bit too much oil.Try 70-1.

Thanks will lean off mixture.

Tried putting finger in spark plug hole but engine wouldn't start???...guess there wasn't enough spark in my finger.

Took it back to BVM turns out the jet and breather pipe was blocked so both replaced FOC. Seems OK now.