49cc is fine. But for insurance it depends on whether bike ends up being classified as a motor vehicle or not. Above 50cc you'd have to apply for a title and registration and plates before you can get it insured. If you tell the insurance agent it's under 50cc you'll hit the same issue as me. one might be able to get liability for off road use but that's still inadequate considering that we use our motorize bicycles for on road use most of the time. Insurance companies underwrite policies according to use and risk associated with our vehicles and there is a huge difference in the types of risk between off road and on road use. They won't underwrite a policy for a non-motor vehicle for on road use because there is no such provision in the statute that requires it hence the very issue I brought to the attention of the police. If there was such a law that mandates our motorized bicycles be covered with liability insurance and the insurance companies refused to underwrite a policy I'd be filing complaints with the state commission that regulates insurance companies.
The EPA mandates that every internal combustion engine sold/imported into the US must have some sort of label describing the engine displacement and such. The officer that flagged me down yesterday made a point of verifying my engine cylinder displacement.
Years ago these Chinese HT manufacturers weren't labeling the engines and the EPA cracked down on them. We used to see claims from makers and vendors that HT engines were 80cc which was a lie. They were actually 66 or so CCs being marketed as 80cc and so on causing all kinds of drama with both government regulators and consumers. The state won't have any issue determining the cylinder displacement these days so if you do try to use a 66cc engine the police and DMV inspectors will know. Some try to remove the label but that only makes the consumer have to prove the displacement somehow.
From what I've read there isn't that much different in the performance of a 48cc and a 66cc motor if the gear ratios are properly accounted for. My 49cc 4 cycle has enough power to move me around and a 48cc 2 stroke would be stronger than my 4 stroke I would assume.
Thanks, I think my next concern would be since I just ordered the 66cc kit, would I be able to swap out the engine only with the 49cc using everything else. It looks to me like everything matches up manifold wise.