Uh oh Scott, i spy a problem but I do admire your build and enthusiasm! Last summer I did just this same build on a cruiser with a Briggs&Stratton.
These are the only crummy pics that remain of the build. Let me tell you what issues I ran into and what I learned from this particular build. It's my third variation of a motorized bicycle (out of 5 now), and I would prolly never do it this way again.
The center of gravity is waist high which makes the bike unmanageable and also very wheelie happy. Very. I had a giant sprocket on my drive wheel which was all I had at the moment resulting in a very low gear. The full weight of the engine is sitting over the rear axle and at the first sign of an uphill grade or even a pebble in the road the front wheel will shoot into the air. This project only lasted a few miles when the front tire just slid out around a leisure bend in the road and turned the frame into a taco. That's another thing, the front tire has minimal traction being that the weight distribution is now (approx) 15%front and 85%rear.
I would recommend strapping that engine to your book rack and pedaling around the block to get a feel for it, you'll prolly agree it feels like a monkey on your back.
Good luck! Hope my story helps.
