I used to have two different thatsdax 70cc frame mount kits, like most of the guys have here. I got mine from ebay for under 200 dollas U.S. shipping included. The one I have now is a 1979 or 80 TAS Spitz. It's basicly a weedwacker engine with a roller that runs on the front wheel....slow, but indestructable.

The frame mount types are pretty reliable, I did do some major long rides with them both and the only thing I had any trouble with was the gears started to whine, so I had to stop at an auto parts store and buy an oulandishly priced packet of grease for 99 cents and popped the cover off and greased the gears.

I WOULD suggest that everyone make up a small tool bag to mount somewhere. Screw driver (one each) pair of visegrips, maybe a tire patch kit, but that's no good unless you have a pump as well.