So where are we with this thread idea? It has so much potential that I hate to see it fade away into nothing. Even failed ventures inform and help to point the way to success. I have a feeling that there are any number of ways to make this work. Mostly, it just needs doing. No doubt one way is more elegant than another, or less expensive, or more foolproof, but there must be a way.
A year from now will be the winter of 2015-16 and once again I will have two bike projects sitting at either end of my old trailer house in the woods, a 1957 Spartan Royal Manor. I think that one of the bikes is going to be an upgrade project to my American Flyer (1950 Schwinn Panther), which has been my faithful daily rider. It started out with a 50cc huasheng 4 stroke with a Q-matic transmission which is belt initial drive and from the output clutch chain drive to a manic mechanic hub adapter.
Along the way I added a sidecar for Aaniimoosh The Wonder Dog made from part of a Gruman canoe and with the additional weight and drag seriously needed more power. I swapped engines to a 99cc Predator which was a great improvement, but still not the greatest for steep inclines. I don't do pedal assist, thanks anyway. Much as I like this ride, it still wants more power. So, it needs a different engine.
I have a 147CC 2 stroke Jacobsen from a power burst snow blower, vintage 1970's which is a robust little engine and I think it will give power in the range that I want and need for this build. My plan is as much as possible to use what I have on hand and keep the cost down. So, although tempted to go to a CVT transmission I will use the Q matic again, which has been a reliable transmission and is what I already have.
In line with the subject of this thread, I would like to change the final drive over to belt. I'd need to switch the sprocket on the clutch to a pulley of the same diameter and use a pulley at the rear wheel of the same diameter or in the same general range (probably smaller by a bit to increase the top end and lower rpm on the engine). Not sure how yet without staring at salvaged parts, but I should be able to drill and bolt the pulley to the sprocket on the manic mechanic hub adapter. Yes, I would reuse the sprocket and in fact have an old one with worn teeth that would serve the purpose and attach the pulley to the sprocket. The hub adapter will have plenty of bite against the hub, leave the spokes (11 gauge) alone and have some lateral adjustment on the hub. The hub is an older Bendix coaster brake type and is excellent.
I don't wee why this won't work at little additional expense (pulleys and belt). Anyone see a problem? I may need to open up more room at the frame for belt clearance, but will better know that when the time comes. I can mount the engine a bit off center if need be and will be removing the recoil pull start, tinwork,and shaving down the flywheel to shrink up the engine. Engine starting will be by hand crank as I'm doing with two other builds (Elgin Velocipede and "Kindalikeawhizzer" which is also final belt drive to a traditional whizzer sheave).
I thought about doing away with the Q matic and going directly from a pulley at the engine to a sheave on the rear wheel, but this is actually simpler since I have the Q-matic and the hub adapter. When this project gets underway I will do a thread with photos and narrative. It is still a long way off, but I am committed to the engine upgrade and am tired of chain final drive.
Suggestions are welcome.
SB