Re: My First Build Pics (Cranbrook)
B7HS might be too cold. I had one of those lying around and ran it in my 48cc the other day, and it didn't seem to have the power that even the stock kit plug had. The kit plug was a nice light milk chocolate color after several miles, and the B7HS was a much lighter tan after a twenty minute run around the block. Of course, it was about 15 deg F outside, too.
Until you get the dual pull handle, if you're only going to run one brake handle, I'd put it on the front, and make sure you're using it and your coaster to stop under normal conditions.
I wouldn't worry about pulling the motor apart. Just make sure the head nuts are torqued properly (10 foot-lbs, 120 inch-lbs, I think? right?). If you don't go crazy with overtorquing the kit hardware, it shouldn't give you problems right away.
The only hardware I'd advise to replace immediately is the nuts and bolts that hold the chain tensioner on. Get harder bolts and locknuts - anything the hardware store will have is fine. With only two bolts on the tensioner bracket, the bolts and/or nuts from the kit will strip before you get it on tight enough to stay in one place. Then you'll have the chain sliding off into the spokes, wrecking your wheel and possibly you.