homemade jackshaft 80cc raw engine 8speed hub

Discussion in 'Frame Mounted Engines' started by pbeggs, Jul 2, 2010.

  1. pbeggs

    pbeggs Member

    hi all

    im in the end stages of a motorized bike build.
    i used a 1960's murray beachcrusier frame (the engine front mount fits!) an 80 cc "raw" engine.
    i made a rear engine mount (see pic.) and a bearing mounting plate for the jackshaft.,,,

    jackshaft: engine side 30 tooth sproket.
    pedal side 16 tooth freewheel
    rear wheel drive cog 10 tooth

    rear hub: sturmey archer 8 speed with drum brake with 25 tooth cog
    front hub: sturmey archer with drum brake

    it is the best motorized bike i have ever had (my third):D

    Attached Files:

  2. AussieSteve

    AussieSteve Active Member

    Nice looking. That's a good solid jackshaft mount.
    Is it up and running yet?
  3. pbeggs

    pbeggs Member

    its up and running,.. tested lights tonight,. installed speedo 24.5 mph in third gear at 3/4 throttle (dirt road,. still shake testing the thing,..)ill go faster once motor is broken in a little more and i can take longer rides,.. so far a very enjoyable ride.
  4. AussieSteve

    AussieSteve Active Member

    Sounding good. Nothing like having gears on these things. (Got a Sick bike Parts shift-kit into 6-speed derailleurs on mine.)
  5. skyl4rk

    skyl4rk Guest

    What kind of freewheel are you using on the pedal cog?

    Where did you get the parts?
  6. pbeggs

    pbeggs Member

    where did i get all this stuff?

    pedal side of the jackshaft is a standard 16 tooth freewheel on a freewheel adapter from staton inc (5/8 shaft 3/16 keyway)
    rear wheel chain drive cog 10 tooth for 410 chain also from staton on 5/8 shaft w 3/16 key

    engine side 30 tooth sproket and freewheel sproket adapter (sick bike parts) on a 3/4"shaft freewheel adapter (staton inc)

    shaft ,.. made by myself on friends lathe and mill 3/4 inch on one end and 5/8ths on other end (if i were to start over it would be a 5/8ths shaft)

    bearings: standard 3/4" flange bearings modified some to make them less wide ( again, made by myself on friends milling machine and surface grinder at work)

    bearing mount plate: 3/16th plate steel from local steel
    supply 1" slot milled up center (friend again)

    rear motor mount: section of mountain bike handelbar(i think) vendor : scrap bike pile outside shed.

    chain tensioner,.. made from a piece of 1"x 1/8" bar stock,
    derailler wheel from pile o' parts, made on a drill press and a small (micro) milling machine(unimat!) with 2 screen door springs for tension.

    this is not a project for anyone whom does not know thier way around a machine shop (im a machinist).:evilgrin:
  7. AussieSteve

    AussieSteve Active Member

    You said it.
    For the rest of us, with only a drill, file and hacksaw, the Sick Bike Parts shift-kit works well.