deXtrous' First Project Journal

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deXtrous

New Member
Hey folks, so I've decided to put togeather a few words with pictures of what I've done thus far.

It's far from finished and I actually could use some help with the gearing and hooking it up.

So far I've got a 49cc cag pocket bike motor, with a front hub from the pocket bike to be used as a jackshaft, and the frame of the pocket bike used as a rack mount. I've also torn apart an old bike to make the forks that lead to the rear wheel hub on the bike.

I'm still cutting and welding the rack togeather so no pictures yet.... oh, wait, it seems I'm very good at balancing, so there is some pictures!

Bike and motor,

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Bike with motor and rack mounted. Nothing is welded, just balancing.

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Up close

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So what do you think?

I don't exactly know how I'm going to get the jackshaft in there.

I have a few questions, I will be running the rear pocket bike sprocket to the jackshaft, but what second sprocket (on the jackshaft) should I use? I know the ratio needs to be around 2:1, but I don't know where to find sprockets or anything.. I mean, do I just use bicycle sprockets? I wouldn't think their chain would be strong enough to support the rpms?

That's the only question I really have at the moment. I'm sure more will pop up when I get further into the project.

Hope you enjoy and I'll be sure to update soon!
 

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Nice build, very clever use of what you have. I assume you are doing chain drive? Good luck with it and I want to see a video of it working when you're done. I'm working on a rack mount and friction drive here in the states. Happy Building!
 
I used a scooter rear wheel for a jackshaft on ome of my bikes- cut the spokes off and sent the power to a sprocket welded to the brake side (actually used part of the brake "Drum" to weld the sprocket onto
welding sprocket, the hard part is getting them to run true tacking them up.
Looks like you already are using some of the frame of the pocket bike. Can you do a similar thing with the rear wheel?
 
motor_head said:
the ratio needs to be around 12 or 14:1
Click to expand...

The current setup has the correct ratio to turn a pocket bike wheel which is about 32". But instead of turning a pocket bike wheel, I gotta turn a bicycle wheel which is about 78". That's 2.5 times bigger, which is 2.5:1, but to handle lower range I'm gonna tune it down to 2:1. (thanks haggard from motoredbikes.com!)

I still really need to know which sprockets are acceptable to use as the secondary gear for the jackaxle. Are bicycle sprockets and chains okay or would I need something a bit more heavy duty?
 
deXtrous said:
The current setup has the correct ratio to turn a pocket bike wheel which is about 32". But instead of turning a pocket bike wheel, I gotta turn a bicycle wheel which is about 78". That's 2.5 times bigger, which is 2.5:1, but to handle lower range I'm gonna tune it down to 2:1. (thanks haggard from motoredbikes.com!)

I still really need to know which sprockets are acceptable to use as the secondary gear for the jackaxle. Are bicycle sprockets and chains okay or would I need something a bit more heavy duty?
Click to expand...

are you shure or does the motor have some internal reduction gearbox
 
motor_head said:
are you shure or does the motor have some internal reduction gearbox
Click to expand...

Positive.... It's a centrifugal clutch system. No gear box or transmission - nothing.

Rather than questioning me, would anyone be able to help me?

I've got it all sorted out. I'm going to add a 3:1 secondary gear to the jackshaft. I'm going to put a LH freewheel sprocket on the left side of the hub. Anyone know where I can get a big enough freewheel sprocket?
 
You could grab a disc brake rear hub and make an adaptor to fit a chain ring on the LHS of the hub. Greenspeed & Jackson Bikes make chainrings in the 80 tooth range and both are of excellent quality (would post links but I am not allowed :( ) This does mean that you will need to run bike chain though.

Another thought would be to use gokart chain ring. Not sure of the gear range available but since you are going to run a jack shaft to drop the revs this would not be an issue. Gokart chain should have no issues with the power either.

Or you could use a cambelt and pulleys from a motor if you could squeeze them into your frame.
 
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