Deraileur Transmissions


New Member
Local time
11:45 AM
Jun 19, 2008
West Virginia
I've got a very neverending supply of large chainsaw engines...39-50CC's. I have to buy them, but they generally go for under $30 each brand new. Anyway, I have a happy time motor, want to play with putting one of these chainsaw motors on another bike. Really, REALLY looking for anyone who has successfully rigged up a pseudo transmission using the rear deraileur of any given bike. (Especially if the bike is still pedal-able, we have lots of huge hills around here.)
I cant wait to read the specs on this setup and please post pics too.
Nice bike and excellent workmanship. Isnt a deraileur the mechanism that shifts the chain from one sprocket to another? In the original post he specifically states rear deraileur.
Well the bike is pedal-able, and can shift, under both engine and pedal power using the rear derailluer. I thought that is what he was talking about.
I had actually seen both those threads, but was hoping to avoid the jackshaft via rear mount above the rear tire, and physically using the rear deraileur. It occours to me that the rear cassette is perhaps too tall for the motor, though.
By too tall I assume you mean gearing, you would need to reduce you engine axle speed substantially prior to hooking up with the rear cassette. You would also need to move your derailluer so that it would pick up the chain as it enters from above as opposed to the front, but if you do that then you couldn't pedal it anymore. I guess 2 chains would be an option but shifting either or both would be a dicey proposition.
Right, thus my conondrum. My real reason for wanting to pursue this is that I live in the mountains here and hills are a real issue. My little HT motor isn't anywhere near broken in yet, and it really does ok on them, but I believe that it can do waaaay better. Like I said, I saw a fellow way bigger than I am pulling quite a grade without pedaling at probably 30-35mph, and his motor didn't appear to be any bigger than about 50cc. It was mounted directly above the rear wheel, and I didn't see a friction drive as per the GEBE kits.

The cost of the jackshaft kit is the real killer for me on your front sprocket setup there. If you've got any messenger program (msn/aim/yahoo/whatever) I'd love to pick your brain a little closer to "real time."
Most likely what you saw was a 4 stroke rack mount kit. 4 strokes have good torque. I don't use IM's, not that kind a guy. Send me a PM and we'll talk.
Tom after looking at ghosts setup isnt that exactly what you want? You could have a 6 or 7 sprocket cassete on the rear and that would give you the gears to choose from.........nice setup ghost.