Re: New to Motor biking, What kit is best??
With that budget you could afford a better bike than the Walmart quality ones. This pays off, trust me, though many Walmart bikes end up as good conversions. I'd recomment the Grubee GT1 bike (Check Pirate Cycles, one of our sponsors). It's got many "Must haves" built right in like front and rear brakes and a "direct to hub" drive system instead of the "Rag joint" used in the kits. If you go with another bike, spend the money to get a hub adapter and toss the Rag Joint sprocket. I've built four of these bikes and the biggest problem always seems to be that rag joint killing the spokes over time.
All my bikes use 2.25" x 26" tires and I've never had a problem with chain clearance, though I admit it can be close at times.
So, in summation, plan on a bike that either has, or can be converted to use standard front and rear brakes (disc, cantilever, v-brake) as the coaster brake on 1 speed cruisers is NOT sufficient for the speed of these motors. Replace the rag joint sprocket or better yet, don't even use it in the first place. Front suspension is very nice, like the "mountian bike" style on the GT1 or a springer fork, which just looks kewl.
One last thing...be prepared to become an addict. Welcome to the club!