"would i lie to you, honey?"
box-sellers are box-sellers...2- or 4-stroke, frame-, rack-, or beanie-mount, you can bet the farm they're clueless about "whatever" is in the box. but, no matter the particular style of drive you prefer, there's always a couple examples that will excel...do your homework and find one, it's worth the time, and it helps the next new rider/builder who comes wandering in.
there are quite a few different engines and styles i admire, or i could say
have admired...i've been blessed with a close look at a diverse selection.
my generic opinion for a topic like this goes as always: i'll never strap another non-
certified engine on my bike ever. certification is the maker's financial show of proof that you are getting what is being claimed. if someone would lead you on about "approved", "designed by", or any other such nonsense, how can you believe their claims about the internal quality of their "replica."
with that said, i can honestly say that some of the drive-trains i've admired were only lacking one thing. it was the certification that proved loyalty to fair and honest trade in our market, a bit of dedication to pitching in & cleaning things up a bit, and the downright
genuine desire to help the economy instead of contributing to it's downward spiral.
please choose first to buy a quality clean engine,
then choose your favorite style, and
then you can go looking for the right supplier...
you'll wind up with a motoredbike like you wouldn't believe, you'll wind up with one you'll
still LOVE 5000 miles later