"Fun" with sprockets

Discussion in 'Performance Mods' started by Doppelgamer, May 7, 2007.

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  1. Doppelgamer

    Doppelgamer Guest

    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?

  2. Guest

    Guest 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.
  3. Doppelgamer

    Doppelgamer Guest

    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...
  4. Doppelgamer

    Doppelgamer Guest


    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. :grin: 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...
  5. locoWelder

    locoWelder Guest

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

    Edward Guest

    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.