This is the 2nd 66 I've had, and neither could hold a candle to the 48cc bike.
I have a neat little secret I'm about to reveal with the 48. I have to install it first
Anyway, today I swapped the spark plug and did a plug chop. Everything's in order, so once I get back home again I'm probably going to hit both with a degree wheel and a set of calipers.