Okay, with everyone's help I've achieved quite a lot. Current plans are to build a China Girl 66cc using a Walmart Special Huffy Cranbrook. I received my motor today and have yet to open the box and familiarize myself with the parts as well as make sure all the parts are there. Most of the information I've seen shows bikes without the chain guard so I may remove that one part before I pack the kit for the plane ride to Puerto Rico. I also have my powerful Cree headlight, bar end mirror and a cheapie tail light. The big question is: Do I buy a JackShaft or ShiftKit? Being able to keep up with traffic will be much safer in Puerto Rico where drivers are very aggressive and the roads don't have much of a shoulder. My concern is that I'm getting into a much more lengthy build where I can run into mechanical snags when time is very limited during my 3 week stay. I noticed a note on Sick Bike Part's Shift Kit page that says to make sure I measure the seat post shaft to order the right kit. Do most cheaper mountain bikes have the same size seat post shaft size? What about a build using a 3 speed (internal rear hub shift) bicycle with a JackShaft kit? Would a 3 speed give me enough of a speed variability to be worth it? Would it get me up to say 40mph? I'm thinking it would.