Re: Which engine is best??
I've bought 4 motor kits from BGF/LEB/Rico group. They're service and parts have been good, but all their motors were crap.
I made 1 motorized bicycle using a ShyHawk 80. It was better than the BGF motors.
I've bought 4 motor kits made by Flying Horse. So far they've been my best by far, so they are the ones I recommend. Flying Horse has Japanese crank bearings. All of my Flying Horse motors have run the smoothest of all. I feel this is because they have the best, balanced crankshafts. Their pistons are also lighter than the ones in other brands. Having said this, it's still a important to remove the covers and make sure the gears, and seals are installed correctly, but you need to do that no matter what brand you buy.
Good luck with whatever you buy.