Cheaper Jackshafts?

Discussion in 'General Questions' started by willfargo, Aug 25, 2011.

  1. willfargo

    willfargo Member

    I've been searching for a jackshaft, and the only pre-made ones i have been able to find are the ones from
    However! $200+ sounds extreme for such a simple small part!
    I have found many threads of people building their own, however none seem specific enough to really get my head around what is needed. Can anyone point me towards a thread or link of a specific and simple build? or does anyone know of an alternative jackshaft that is less than 200?


  2. professor

    professor Active Member

    You must be thinking of the shift kit they offer. That is a lot more than a jackshaft.
    I bought parts from McMaster Carr (credit card) for a jackshaft set-up. You select what you want from their vast array, punch in bearings, and shaft. You can get pillow block bearings (cheapest ones are about 10$ each) pulleys, sprockets and keyed shafts and chain.
  3. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    You get all these parts for $200 from Sick Bike Parts.
    You can order separate parts from the kit.

    What motor are you using the jack shaft with?

  4. willfargo

    willfargo Member

    Im still trying to determine what engine to get. i was looking at a 66cc, however my towns ordinance requires it to be lower than 50cc, and i was told that somehow 49ccs can be tuned to run much better than a 66cc. any recommendations?
  5. professor

    professor Active Member

    Take the CC badges off and it is unlikely anyone will ask about the motor. From talk here, the 49s vibrate less.
  6. willfargo

    willfargo Member

    ok. So say i have a 50 mile commute to a college town i take ever weekend. What setup would be best for getting me a long distance. Something that can average 35-40mph. Fuel boosters? what are the best carbs? what engine? i'll probably save up and go with the SBP shift kit
  7. professor

    professor Active Member

    To me the best set-up would not be a china 2 stroke from what I read on these motor bike forums. 25 miles would be a long way to pedal with a dead motor.
  8. Big Red

    Big Red Active Member


    The Professor is right. You can't tell by just looking what cc it is. The only way to tell is to take off the head and measure it. So go with the 66/80cc, And when asked, Your response is always, Why, yes officer, It is a 49cc. I've been doing this for almost five years now with no problems. I don't think a cop is gonna take you're engine apart to find out what cc it is. But hey, I'm just a rebel at heart, so do only what you feel comfortable doing.
    The easiest, and cheapest way to hit 40mph is with the 66/80cc chinese engine. If you go with the 49cc I'm afraid you'll have to go with the sbp shift kit, or something like it, to hit 40mph.
    Big Red.
  9. IbedaYank

    IbedaYank Member

    the HT kits and sub $200 is not the best choice for this kind of use
    the grube kits or similar are LOT more reliable
    and will last lot longer
  10. IbedaYank

    IbedaYank Member

    round head...under 50cc...square head over 66cc
  11. happycheapskate

    happycheapskate Active Member

    Get a Staton Drive or Thats Dax friction drive and a 52cc harbor freight motor or high output pocketbike motor. You're not going to average 35mph though unless you have a long straight commute and no stops.

    NOTE roller size and engine RPM cruise speed are important. Ask before you purchase parts. Staton offers the most roller sizes, Dax should have a couple. Tire selection is critical. (probably my next purchase like this)

    I have a china kit bike and I like it, but I wouldn't want to rely on it for a college commute. If your china-kit bike is properly set up and you use heavy duty chains and stuff, it could work, but I would trust a commercial honda clone or japanese branded engine way more than the happytime, and friction drive eliminates a lot of stuff to fail and doesn't look like a motorcycle.

    Last edited: Aug 26, 2011
  12. MikeJ

    MikeJ Member

    I have to agree with Happycheapskate.

    For reliability, get a setup with as few moving parts as you can. Friction drive is pretty simple. I like the jackshaft, but alignment of gears and chains require close attention to detail. I had a chain snap a link when 10 miles from home. That was a long ten miles.

    These china engines tend to vibrate themselves apart. They are a high-maintenance item: bolts break, studs break, engine mounts break. The quality of the metal parts are just not up to automobile standards.

    I doubt you will maintain 40 mph average unless you go with a big engine for its pulling power. More realistic is 25 mph. I *strongly* recommend you get an engine with a cast iron cylinder sleeve. A cast iron sleeve engine will last longer. Run good quality synthetic oil.

    There is a great deal to learn from the contibutors of this forum. Cheap engines can be reliable. But more expensive engines from Japan seem to have a higher satisfaction rating for reliability.
  13. happycheapskate

    happycheapskate Active Member

    To maintain an average speed of 40, you will have to go a lot faster than 40!

    Here is a bicycle at 35mph for comparison (bike camera view)

    Best of luck with your build and your education. I would have liked to have a motorized bike when I was younger. I might have met different people and taken a different career path.
  14. Big Red

    Big Red Active Member

    If that is true, Do ya really think the cops know that?
    Last edited: Aug 27, 2011
  15. IbedaYank

    IbedaYank Member

    one look at the grubee line of kits and that cop will
    but on average no but it just takes ONE cop that does and is in a bad mood..
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