"Fun" with sprockets

[Doppelgamer]

Ok, I have an interesting problem here.

I am trying to mount a pocket bike engine above the front wheel of my bike. The front wheel is actually a single-speed rear, where I can run a chain between the pocket bike transmission and the wheel.

Here's where it gets hairy.

The stock sprocket on the pocket bike tranny appears to be a #35 from what I understand about chain pitch. The bike sprocket will be a #41 when I am finished (welding two sprockets together). I have a drive sprocket I purchased that is a 9 tooth #41, but it is a 5/8" bore, and I need it to fit a weird splined shaft with 6 splines and of a diameter of ~1/2" I tried looking on pocket bike websites hoping they made a conversion kit, but no luck so far.

The only other thing I can think of would be to take the two sprockets, have them machined down and welded together to form one good sprocket. This method can still be reliable, but is a little more time consuming.

Any ideas other than what I have come up with so far?

 

[Guest]

I would suggest a web search of motorcycle/gokart/minibike places for the proper 1/2" six splined, #41 sprocket, I know someone makes one.

Or cut the teeth off the old one and weld the new one to it.

 

[Doppelgamer]

Right now I am in the middle of option 2. I work at a company that manufactures filter systems and they have a lot of machine operators. I think I can talk them into machining the sprockets to fit the splined hub into the sprocket I need. I'll keep fiddling with it until I figure it out. That's usually how I go about things...

 

[Doppelgamer]

The gear on the left is the gear I need to use. The splined spacer on the right is what happens to a sprocket when I play with a grinder. I want to have a machinist turn down the spacer a bit and drill out the sprocket so I can fit the two pieces together and weld them. If I knew what I was doing on a lathe I would do it myself. I'll have to entice them with doughnuts or something...

 

[locoWelder]

green stuff works best ,ya know that stuff that the wife take from you

 

[Edward]

Ran into the same issue with my standard mounted motor. The sprocket is a #25. Machining a new engine sprocket is $200. Tossing the moped wheel and buying 2 #25 chains and a rear sprocket to use on a standard Stingray wheel is $60. Guess which one I'm going with. Re-inventing the wheel is for people with more time and money than I've got.