professor
Active Member
This is for field use, no peddling- for street, it would need a second jackshaft rater than using the crank shaft, and would need a one way sproket deal.
The bike is one I got at a curb sale (garbage day) and fixed up a couple of years ago:
The engine mount is eighth inch steel straight back off the one side with a support bracket mounted where the electric starter was to the frame. Seems pretty solid, of course the frame itself will flex a bit since the notor is cantilevered back so far.
Initally, i wanted to use the petalcrank to also power the bike so the motor does clear the back of my boots.
I did not want the engine on the rear triangle bouncing around and adding lots of un-sprung weight, thus the rear frame mount, motor only weighs 10 pounds, have yet to add a muffler system and aircleaner- maybe 3 pounds.
Ideally this would be a great set-up for a chainsaw motor and it's cent. clutch, gastank and muffler.
So far I have had to actually buy a crank tool (Avner crank puller fromUSBIKEBARGANS- got it in a couple of days), a 9 tooth #41 sproket from McMaster carr another fast delivery) and a v-belt. Everything else I had.
Here is a pic of the jackshaft (plain brgs. -had them for decades but ball would be better)- it is slotted for adjustment and mounted on a 1/4 inch bracket with small gussetts-
Oh, here is a tip- if you have a jackshaft with no keyway, or sprockets/ pulleys without them, you can place the shaft on the item and drill the end so that one half of the hole is in the shaft and one half is in the pulley, then you tap it and put a long set-secrew (or 2 short ones) in the hole. They become a "Key" of sorts. Locking it both from turning and coming off. The downside is they become dedicated. I used quarter twentys in the 1/2 inch jack shaft.
The concept is to reduce the gear ratio a real lot before it gets to the derailur, thus the 4.5 ratio from the engine to jackshaft and 5 or so to one down from the shaft to the large chain ring. I am hoping the small sproket to the derailer will be enough to kill the ratio some more - I am only looking for around 20 mph and down.
The next pic shows how I drilled the rivets out of the ring in order to affix a big washer with other washers welded to it (my adapter) which will carry the small sprocket you see in my hand welded to the "adapter".
The trick here wil be getting the little one to run true. Think I will weld studs to the adapter, measure the sprockets to center as much as I can then clamp and tack weld the sproket to the adaptor.
Then, bolt them together lightly and set the ring sprocket in place (tight). Then spin it and make sure I can tap it true, go back and final weld the sproket to the adapter, re-mount, tap true and tighten down and tack weld the adaptor in several places.
Was anyone un-able to follow that explaination?
There is a lot yet to do. Gotta come up with footpegs, and a bunch of other things.
Will do more updates as I go..........
The bike is one I got at a curb sale (garbage day) and fixed up a couple of years ago:
The engine mount is eighth inch steel straight back off the one side with a support bracket mounted where the electric starter was to the frame. Seems pretty solid, of course the frame itself will flex a bit since the notor is cantilevered back so far.
Initally, i wanted to use the petalcrank to also power the bike so the motor does clear the back of my boots.
I did not want the engine on the rear triangle bouncing around and adding lots of un-sprung weight, thus the rear frame mount, motor only weighs 10 pounds, have yet to add a muffler system and aircleaner- maybe 3 pounds.
Ideally this would be a great set-up for a chainsaw motor and it's cent. clutch, gastank and muffler.
So far I have had to actually buy a crank tool (Avner crank puller fromUSBIKEBARGANS- got it in a couple of days), a 9 tooth #41 sproket from McMaster carr another fast delivery) and a v-belt. Everything else I had.
Here is a pic of the jackshaft (plain brgs. -had them for decades but ball would be better)- it is slotted for adjustment and mounted on a 1/4 inch bracket with small gussetts-
Oh, here is a tip- if you have a jackshaft with no keyway, or sprockets/ pulleys without them, you can place the shaft on the item and drill the end so that one half of the hole is in the shaft and one half is in the pulley, then you tap it and put a long set-secrew (or 2 short ones) in the hole. They become a "Key" of sorts. Locking it both from turning and coming off. The downside is they become dedicated. I used quarter twentys in the 1/2 inch jack shaft.
The concept is to reduce the gear ratio a real lot before it gets to the derailur, thus the 4.5 ratio from the engine to jackshaft and 5 or so to one down from the shaft to the large chain ring. I am hoping the small sproket to the derailer will be enough to kill the ratio some more - I am only looking for around 20 mph and down.
The next pic shows how I drilled the rivets out of the ring in order to affix a big washer with other washers welded to it (my adapter) which will carry the small sprocket you see in my hand welded to the "adapter".
The trick here wil be getting the little one to run true. Think I will weld studs to the adapter, measure the sprockets to center as much as I can then clamp and tack weld the sproket to the adaptor.
Then, bolt them together lightly and set the ring sprocket in place (tight). Then spin it and make sure I can tap it true, go back and final weld the sproket to the adapter, re-mount, tap true and tighten down and tack weld the adaptor in several places.
Was anyone un-able to follow that explaination?
There is a lot yet to do. Gotta come up with footpegs, and a bunch of other things.
Will do more updates as I go..........