Hey, everyone! Given that there is still very little information out there about these kits (cannonballs2 being the only other user I've seen actively posting anything on them), I'd like to share my build.
I have desecrated, er... revitalized a 1985 Trek 400 road bike by putting flat bars on it, and removing the shifters and rear derailleur. Oh yeah, also the huge (and I mean huge, this thing is incredibly wide) engine bolted to the frame. As a first note, if you're going to use a older chromoly/steel road bike frame, I would not go smaller than a 56cm or equivalent, you'd have to do some modifications to the wiring to get a 54cm or smaller frame to work. Note you may have to shim out the frame for the junction box or chain tensioner, though the engine itself along with the fuel tank and battery should mount up just fine.
On the subject of old road bikes, make sure you have decent wheels and spokes. My 30+ year old spokes began to snap from the torque this engine provides, if you're gonna go with 27" wheels, try to steal some off of a Schwinn Continental, those wheels are tanks. The front wheel doesn't matter as much as the rear wheel, it doesn't bear as much weight or nearly as much torque.
I was originally skeptical (and rightly so) of the battery mounting location under the bottom bracket, but it seems to be okay, but my eagerness to ride meant that I lost a bolt on the front mount which caused my battery to drag along the ground for about 100 feet, but the plastic casing stayed in place and kept it intact, thankfully. If you want to lengthen the wires, you can (and probably should) mount it inside of its case in a bag on a rack, much better in my opinion. You could also go the route cannonballs2 went and use a hobby shop lipo battery, which is smaller and lighter but still turns over the engine just the same.
Contrary to what Bikeberry will tell you, your kit will come with a 48 tooth sprocket, not a 44. I recommend downgearing to a 44 at the least, this thing has more than enough bottom end to do it. I run a 27" wheel and am thinking about going down to a 41 from my current 44.
The electric start works, and it works very well. Today the high was 5F where I am, and with any choke whatsoever, it would not start. It started right up like it was 105F out.
With any motorized bike, mirrors and lights are your friend. The nice thing about this kit is the battery is way more than it needs to be, so you could easily rig up a very nice headlight, taillight (with brakelight functionality if you could find or rig up a switch), turn signals, and even horn. I plan to rig up turn signals and a horn, I will update once I get around to that.
Included are some totally 100% non-sarcastic wonderful quality photos of my build. If you have any questions about the kit, feel free to post them here, or read cannonball's thread linked below; I'm also sure he wouldn't mind people asking questions there, either.
cannonball2's thread: http://motorbicycling.com/showthread.php?t=62224
Image links because they fail to upload as attachments and I don't wanna kill somebody's web browser by loading them all at once: