Jackshaft 5/8 or 3/4?

Discussion in 'Transmission / Drivetrain' started by RocketPenguin, Jun 11, 2015.

  1. RocketPenguin

    RocketPenguin New Member

    I've gotten to the point of my project where i need to begin turning the ideas and theories into a list of materials, and have come across my first question.
    What size of a jackshaft should i get?
    My two options are 5/8 and 3/4.
    A chainsaw engine with 6 teeth will connect to a sprocket with ~30-40 teeth onto the jackshaft, and from there a ~9-17 tooth sprocket on the jackshaft to the rear tire sprocket, with ~36 teeth.
    Would 5/8 be enough to handle it?

  2. KCvale

    KCvale Motorized Bicycle Vendor

  3. RocketPenguin

    RocketPenguin New Member

    Yea, chainsaw is #35. I will have #35 chain and sprockets from the engine to the jackshaft, but will keep the original #25 chain and sprockets for the jackshaft to tire.
    From what I see, the site you linked only sells kits and a few sprockets. Any location where I can buy sprockets with keyed bores for a cheap price? Not looking for anything fancy, I can see the chainsaw engine not lasting for more than a few months, and so I don't want to invest too much. I found a few for a good price, but the shipping is always 15$ or more.
    Also what bearings would you recommend? Again, cheap, but able to bear high rpm. ID needs to either be 5/8 or 3/4, and OD needs to be 1-3/8".
    For shaft, since both gears will be on the same side, I was thinking of just buying a 6" bolt, and cutting out my own key shaft? If I go with 5/8, I could buy a 3/4 bolt and lathe it down to 5/8 in order to remove the threads... Again, I am really trying to cut corners and keep this cheap. I know cheap sucks, but this is more for laughs/a short period of time.
  4. The_Aleman

    The_Aleman Active Member

    Exactly why I think it's funny you called SickBikeParts the "king". Staton-Inc was making jackshaft parts for MaBs over 20 years before SBP.
    I wouldn't call them the "king" either, but when it comes to MaBs, they have SBP beat. I love SBP, but I just can't let what you said slide without a retort.

    Anyway. OP: try JSE, they have very reasonable prices on sprockets, it's who I use for my projects. Obviously you'll have to compromise on teeth count with 3/4".
    link: http://www.jackssmallengines.com/eq...art/go-kart-sprockets/engine-sprockets|192:35
  5. RocketPenguin

    RocketPenguin New Member

    Prices look good (Haven't looked at shipping yet) But yes, as you said, limited on teeth. I need a #35 chain 54t sprocket, and a #25 chain sprocket with the least number of teeth possible and still have a bore size of either 5/8 or 3/4 (Still haven't decided)
    The only sprocket I found with 54t was this but it has 0 specs, other than tooth number.
    Might buy the smaller sprocket from here though, depending on shipping costs. Would like to buy both on the same site though...
  6. The_Aleman

    The_Aleman Active Member

    That Manco 54T wouldn't be ideal as it has a proprietary bore center and holes drilled for some proprietary thing.

    JSE has a 54T aluminum #35 blank with 1" bore center
    link: http://www.jackssmallengines.com/eq...art/go-kart-sprockets/engine-sprockets|192:35
    Obviously it would need a hub adapter and JSE doesn't seem to have one that works directly with it.

    MFG Supply has a hub adapter in both 5/8" and 3/4" that will work with a JSE blank. You just need to drill 3 holes in the sprocket.
    5/8 link: http://www.mfgsupply.com/gomini/gominisprockets/gominisprocketshubs/az2037.html
    3/4 link: http://www.mfgsupply.com/gomini/gominisprockets/gominisprocketshubs/az2038.html
    They also carry sprockets, but their selection is much more limited.
  7. RocketPenguin

    RocketPenguin New Member

    The Hub adapter is nice to know, I might be able to find a cheaper sprocket that works with that, but with the sprocket and adapter, I could still get this for less. That's the cheapest I have been able to find, but am hoping I can find a less expensive one...