Not much difference in the two engines cosmetically, 48cc is just that, 48cc and 66cc is just that, 66cc, the difference is in the bore, and honestly I'm not sure if the have the same stroke or not, never had a 48cc engine in the china girls, no cop in any state can look and tell which is which between them and as far as I'm concerned that 48cc law is just a bunch of commy B.S. ( Biscuit Sausage....LOL! ) anyway, If you're on a 48cc bike cruising 30mph down the road or on a 66cc bike cruising @30mph down the road, what the heck does it matter......!
Anyway, if you get a 66cc engine kit you will have a much larger selection of stock parts and upgrade parts to choose from, the 66cc engines are where it is as far as I am concerned, why would I want something that basically cost the same in every way that will play second fiddle to the 66cc for power, speed and parts selection for repairs or upgrades.... to me the choice is a real no brainer.
I have seen where some have said they think the 48cc engines are a bit smoother running but I have no experience with them and I am currently running a GenIV balanced crank lower from Dax, and personally I cant see any stock 48cc engine running any smoother than mine does, so it would be of no use at all to me to own a weaker less upgradeable 48cc China Girl.
But I also say to each there own, and if you like the smaller slower weaker engine..... by all means go for it.
Peace, map
Other than cc size difference between the 48 and 66; what are the differences in the motors?
Sorry if already asked. Search function has me baffled.
OH and I'm new...lol.