Best engine for go-cart?

[Antec1200X]

polaris 800 storm engine done to the nuts lol

 

[Paulie B]

A 5hp briggs gocart was my best friend for a while while I was a kid.
I believe mmajay made mention of a good point, it's MUCH easier if you start with a horizontal shaft motor. The everyday vertical shaft like the ones found on push mowers are hard to mount up.