Got a really tidy old YFM200 for the wife to cruise the beach on. It starts instantly and idles away really quietly, great wee motor.

But...when put in gear and given some gas, it makes a noise like really loud 'pinking, or detonation"...like a higher performance motor would make with low octane gas.

It is run on 95 octane, and starts so easy I doubt the timing could be out...but any ideas? Rides okay, just the pinking type noise when maybe the clutch is working on takeoff. Oil and filter changed with Castrol bike oil.

Cheers