Originally Posted by tyrslider

All of these motors have the same cases as far as I can tell from pics. Some claim to have Japenese bearings, small end roller bearings or needle bearings. I would think that they all have roller bearings @ the big end and the premiums have needle bearings @ the small end instead of a bronze bushing.
I have had the bushed and the bearing engines, and engines from at least four different "sellers" and I can say I have found not a lot of difference.
What are the other differences? Some claim EPA compliance others don't. Doesn't matter unless you live in California.
Above 49cc, actual displacement seems ambiguous.
Yesh! Anywhere from 55cc to 80cc but all are around 67cc. Not a worry, they are just a bicycle engine to put around with. About 3 horsepower.
They range in price from $49.95 (the cheapest and self professed non premium), and "premium motors" range from $150-$350.
That's a funny thing...there are good dealers/seller and there are so-so, sellers. I have bought a Livefast 55cc "non-premium" engine kit and service was good, the kit has a few cheaper parts and doesn't have deluxe goodies, but beyond that, I can't tell any difference from the other engines I have had.
If you look in the "classic posts" area, there is a "find a dealer" there. That may help you too.
Thanks!