I got an e-mail from Motoredbikes and this thread was mentioned. I read it. I used a motorized rack mount as my only motorized transportation for two years. The Golden Eagle was the first kit. The motor lasted the longest but the kit kept breaking spokes. That got expensive to fix. I hated dealing with that. Then the metal brace that held the engine cracked in half. It had to be replaced. Eventually I gave it up for a friction kit from Staton. With the one inch driver it lasted only a few months before the diamond pattern was just gone and the traction was much less. They don't work on rainy days even with diamond etching in the metal. The bearings wore out in those few months too.
Next I ordered a Chinese four stroke motor kit from some big retailer. It leaked oil from day one. It was exchanged. The second one leaked oil the same way and was returned. I spent over $110 on postage for defective motors. I got my $160+ back. I really liked the torque and lower noise even though it was slower.
Next I created my own rear rack mount using my original 32 cc Tanaka motor and a donut left sproket setup. It worked well but the mount was always twisting and needing adjustments. Then the shaft on that motor broke. A friend gave me a 2-stroke weed trimmer motor from Sears. It was fifteen to twenty years old. It worked. That was my last motor until I gave up using it.
I could have purchased a Honda Metropolitan or Ruckus for the money I kept pumping into my motorized bicycle in those two years and 8000 miles. There would have been less maintenance and frustration PLUS the scooter would probably still be running. The only benefits were no insurance and the bike could be carried upstairs and locked to the railing outside my apartment. It couldn't be kept inside because it stunk.
The price to build a motorized bicycle that would last for thousands of miles without lots of maintenance would cost more than a new Lazer 6 moped by SSR ($1599). I still have a Tanaka 32cc replacement clutch that I didn't get to use. Anybody want to buy it?
If I were to do it again, I would want it to be legal, meaning under 50ccs. I would want a Honda or Subaru four stroke engine, and some kind of chain drive on a rear double or triple wall wheel with spokes that would never break. I found a Schwinn frame that I like with front suspension and it costs $500 alone. Everything I've listed puts this over $1400 and there are still parts that I would want to add for comfort; like a suspension seat post and a better seat. Adding a drum front brake would get me over $2000. Honda sells the Navi 109cc motorcycle for only $1807. It goes 50 mph and would be a very reliable vehicle.
Maybe I just want my money to give me a better return when it comes to pricing vehicles. Gas N'Go with few problems. That is my ideal two wheel motor vehicle. Generally motor scooters that are treated well last 30,000 miles. Some people in Asia claim that their Honda Cub motors can last three times that many miles. Yamaha is in the electric bicycle market now. Some are selling for $3499. Uhhhh no. There are lots of options for reliable low cost low speed reliable transportation.