Jayaco 72cc 48mm zuma, jog cylinder
Here's a great budget 72cc (48mm) cylinder, that makes power similar to higher end cylinders.
Comparable power to the polini corsa, uses stock head.
You will not find a higher performing 39mm stroke cylinder for this price!
We dyno tested this on a jog, with a 17.5mm dellorto, and yasuni R exhaust, and saw 9hp, and it beat out the streetrace we tested it against.