3-Speed motorized bike experiment

[Blaze]

Here is the bike from the left side. A few things are still temporarily mounted just for testing. The derailleur is strapped up out of the way, while the bike is currently set up to use just 1st gear only.

This is the left side where you can see the motor chain going to the jackshaft.

Here is a good photo of the second version of the jackshaft mount. I don't know if I will make a third, or keep this one. I decided that it would be better to bolt the jackshaft hoder on by using it as the backside to the motor mount. No welding for the mount will be required (which is good, because the frame is aluminum). The sprockets on the jackshaft will have to be welded. They are currently riveted on, but the rivets really aren't strong enough for permanent use.

This last photo shows how I crammed the carb in there. The air filter housing basically got cut down to a small ring, then I cut the screen and sponge to fit into the smaller area. The manifold puts the carb right up against the motor, and the carb is angled slightly sideways to clear the clutch cable mount (which was cut short). The carb is actually held up by safety wire right now because I damaged the manifold upon installation. It is a little wobbly, but it ran OK for testing. A stainless steel manifold will probably be necessary.

 

[psuggmog]

Thanks for the update. I had a few thoughts about your hub jackshaft sprocket mounting. 1)Use grade eight allen head cap screws instead of rivets. Welding would possible create runout(wobble) of the sprockets due to uneven heat distortion. 2)Consider using a flipflop track hub for the jackshaft. These hubs have threaded cog mounts and separate lockring threads on both sides of the hub.

 

[Blaze]

I like the flip-flop hub idea, but the cog threads are going in the opposite direction from what I need. The motor force would be working to unscrew them. I think I will incorporate the idea for using screws or bolts, though. I'll get some more holes drilled through it, and put 9 hardened fasteners through each one.

 

[Blaze]

OK, until I get the pull starter for this thing, it's nearly impossible to get a decent chain tension on both sides of the jackshaft. I have been tinkering with different sized gears and 1/2 links in the chains, but I can't get it just right. It's always a little tight without enough slack to straighten the jackshaft out perfectly.

That said, I did get it straightened out enough to run it in 2nd gear tonight without throwing the chain. Right now, I think the gearing is equal to a normal bike with a 26 tooth gear on the back. After running it, I don't think my 3rd gear is going to be of any use at all. I was going really fast, and it was still accelerating, but it's going to take a while before it hits top speed.

It will be nice to run it again after a tensioner is hooked up and the jackshaft is perfectly aligned. I was a little nervous about giving it full throttle at that speed because it's the torque that throws the chain. If I accelerate slowly, it seems to do OK.

Anyway, I don't think there is any real progress to be made until the derailleur is re-installed, but so far, things are looking good. It looks like it will end up being a 2-speed, though, since 3rd gear will probably be useless.

I need to get a speedometer on this thing.

 

[gone_fishin]

here's another solution!

these guys use a freewheel crank adaptor, and the prices are way reasonable...this in conjunction with a simple jackshaft and you can have all the gears your rear wheel can handle.

http://www.cyclone-usa.com/installation.php

 

[-=MaTEoS=-]

Here is the bike from the left side. A few things are still temporarily mounted just for testing. The derailleur is strapped up out of the way, while the bike is currently set up to use just 1st gear only.

This is the left side where you can see the motor chain going to the jackshaft.

Here is a good photo of the second version of the jackshaft mount. I don't know if I will make a third, or keep this one. I decided that it would be better to bolt the jackshaft hoder on by using it as the backside to the motor mount. No welding for the mount will be required (which is good, because the frame is aluminum). The sprockets on the jackshaft will have to be welded. They are currently riveted on, but the rivets really aren't strong enough for permanent use.

This last photo shows how I crammed the carb in there. The air filter housing basically got cut down to a small ring, then I cut the screen and sponge to fit into the smaller area. The manifold puts the carb right up against the motor, and the carb is angled slightly sideways to clear the clutch cable mount (which was cut short). The carb is actually held up by safety wire right now because I damaged the manifold upon installation. It is a little wobbly, but it ran OK for testing. A stainless steel manifold will probably be necessary.

ok.. i have a question for the carberator. does cutting the pipe on which you slide the carberator on alter the fuel mixture or speed of the obike.?
i need to do this in order to fit the engine on my bike though i want to know what are the risks if any..

also what did you do to solve the petrol tank?
i can see how there are brake cables and gear cables running under it.
how did you fix it so the tank owont affect it?

im thinking of welding a bridge over it.

 

[psuggmog]

The filpflop track hubs have a lockring threaded with a left hand thread to keep the cog from unscrewing. I just got a hub off an exercise bike that had a large wheel rivited around the hub. It was threaded for a track cog and lock ring. There is no spoke flange just a undrilled flange with four nutches at 90 degree intervals. I thinking this might make a great jackshaft hub. Pictures to follow when I get back home.

 

[Blaze]

ok.. i have a question for the carberator. does cutting the pipe on which you slide the carberator on alter the fuel mixture or speed of the obike.?
i need to do this in order to fit the engine on my bike though i want to know what are the risks if any..

also what did you do to solve the petrol tank?
i can see how there are brake cables and gear cables running under it.
how did you fix it so the tank owont affect it?

im thinking of welding a bridge over it.

The carb will be fine with a shortened pipe as long as the new pipe doesn't have any leaks.

I have not finished mounting the tank yet. I really haven't worked on it much the last week or so. I am waiting for the owner of the bike to order a rope pull start before any more real progress can be made.

 

[wavygravy]

gears!

on my pocket bike they used a dual sprocket set up on one hub, drive chain to one side of the dual sprocket then down to the drive off the other side to drive sprocket! takes all pull off engine drive shaft! might mwork great on derailer set up!!

 

[locoWelder]

maybe something like this would help you

just a thought