49cc Shifter vs 79cc Direct Drive?

Discussion in '4-Stroke Engines' started by Chris Duke, Aug 10, 2016.

  1. Chris Duke

    Chris Duke New Member

    Hey everybody, I've been enjoying reading posts here while trying to decide on what way to go with my first project. I should be starting to order parts by this weekend, and would like some feedback on kit selection before I start ordering.

    It's come down to two choices.
    1. 49cc HS kit's set up with a SBP shift kit.
    http://www.gasbike.net/collections/...-drive-kit-with-huasheng-49cc-4-stroke-engine

    http://www.sickbikeparts.com/catalog/index.php?cPath=21

    2. 79cc HF Direct drive setup.
    http://www.gasbike.net/collections/...ucts/79cc-monster-80-bike-engine-kit-4-stroke


    I figure either would be acceptable. The shift kit would be sweet with the 49cc bike, but I'm guessing that the 79 would be ok by itself with direct drive. And I can't find a direct drive for a 79cc setup, so at least for the moment, it would have to be dd until I came up with my own shift setup.

    Does anyone make a primary / trans with the secondary shaft to extend from the left side to the right side of the bike? It would be nice to eliminate the extra jackshaft assy and the additional chains required for that setup.

    Or what about a swap over at the pedals? Where instead of on the right side, where it would be coming off the jack shaft, the chain to pedal sprocket just drops down from the output sprocket on the primary / trans instead, eliminating the need for the jack shaft kit. Only problem I see (with my limited experience) would be chain alignment between the two. Or, what about running a V-belt from output to pedal assy on the left side? I don't think it would be too hard to weld a old Chevy or Ford pulley to an extended pedal shaft, but would a pulley fit behind the back side of the primary / transmission plate?

    Anyway, some thoughts I had.

    So, if you could only have one 4 banger, and your choices were a 49cc HS kit's set up with a SBP shift kit, or a 79cc HF Direct drive setup, which would you get? Advantages, disadvantages?
     

  2. jaguar

    jaguar Well-Known Member

    shift kit gives the advantage of gearing up for the highway and gearing down for hills but the disadvantages are the added complexity, 8% power loss, cost.
    I'd rather see people spend their money to make the engine more reliable and powerful so the shifter isn't needed.
     
    Frankfort MB's likes this.
  3. bakaneko

    bakaneko Active Member

    If you are thinking about the 79cc HF, there are many who have done it and you can always add a jackshift/shifter later if you are bored with direct drive. Here is a recent video of a guy working on his 79cc HF, he bought the kit from gasbike and suffice to say you should watch the video and avoid some of the pitfalls he had. In the end, he has a nice bike. I have the 49cc HS direct drive, my transmission just broke some I'm weighing some options. I would go with the 79cc HF if you are decent with tools. I mean in the end you won't regret getting the bigger engine. Also, watch all of this guys videos before buying anything if you got 79cc HF.

     
    Chris Duke likes this.
  4. JunkyardDog

    JunkyardDog Active Member

    I would love to have a shift kit. One of these days I will build one. Never seen a 79cc motor, they are usually 66cc. However in most states anything over 48cc is ILLEGAL, and if you ride an illegal bike, you are contributing to the problems all MB riders have to put up with.
     
  5. bakaneko

    bakaneko Active Member

    he is talking about the Harbor Freight Predator 79cc engine.
     
  6. Chris Duke

    Chris Duke New Member

    I've decided to just go with the 49cc HF engine for the 4 stroke MB project.
     
  7. Chris Duke

    Chris Duke New Member


    Yep. I watched his video's. Looks a little too big for a MB project. I have a 250cc Yamaha engine. Also too big for MB use.
     
  8. bakaneko

    bakaneko Active Member

    So, are you going with the SBP shifter for the 49cc HS or just direct drive.
     
  9. Frankfort MB's

    Frankfort MB's Well-Known Member

    Nothing is too big:D
     
  10. Chris Duke

    Chris Duke New Member

    For now just direct drive. I found a supplier of beach cruisers cheap. No gears, so no reason for a jackshaft. If I want, when I have the cash, I could add a shifting internal hub with the jackshaft kit. I would still rather have a freespooling pedal crank assy (sprocket on both sides) that I could hook the chain to directly from trans, to transfer from left to right side of bike without a jackshaft. I found some guys who made a prototype, but I don't think they ever went into production. Can't find the video now.
     
  11. FurryOnTheInside

    FurryOnTheInside Active Member

    L
    I think those are in use on some tandems to allow the stoker (rear) rider to stop pedalling. This is like the way the shift kit works to allow pedal start but uses the crank shaft as the JS by somehow having a rotating crank shaft but keeping the rank arms tied together.. On tandems it might as well be on the same side like the SBP and I think most of them are but could be cool for a MB with pedal start.
    Fully independent pedalling where either tandem rider can stop pedalling at any time is also possible with a lefty freewheel on the JS between the riders' cranksets (between motor and pedals in MBs) but is not popular on tandems yet. I'm sure these will be commonplace on tandems in the future because they make sense. I forget which company makes it. . . but it shouldn't be a big step to apply it to the JS on a MB.
     
    Last edited: Aug 13, 2016
    Chris Duke likes this.
  12. Tony01

    Tony01 Member

    SBP shifters are ghey. Go with the direct drive!
     
  13. Frankfort MB's

    Frankfort MB's Well-Known Member

    Depends on what your doing. If you have a lot of hills and a bunch of straights then it would benefit you to use a jack shaft
     
  14. FurryOnTheInside

    FurryOnTheInside Active Member

    Or if you want to carry cargo and be able to get up hills but still use the momentum you get by powering down hill or building up a decent speed on the flat straights too.
     
  15. CrazyDan

    CrazyDan Member

    Lol in California shift kits are illegal as well. Law requires it be single speed.
     
  16. Chris Duke

    Chris Duke New Member

    In the land of EVERYTHING I WANT TO DO IS ILLEGAL!!! Haaaa!!!
    Tax the air, tax the water, tax the gas to build the roads, then tax em again with tickets & toll roads!

    (and if you ride an illegal bike, you are contributing to the problems all MB riders have to put up with.)
    Consent to be subjects of public servants instead of standing up as Americans is the problem. Not people who take part in a harmless activity with no injured party. It all boils down to consent. Back when, gov was the servant, with only the power to protect rights, not violate them, and now they are the master. By the consent of the governed.

    In the words of Abraham Lincoln:
    No man is good enough to govern another man without the other's consent.
     
    Last edited: Aug 14, 2016
    Sohighlyunlikely likes this.
  17. JunkyardDog

    JunkyardDog Active Member

    Almost nothing is legal in CA. Many of the things I own and do are illegal in CA. AZ has vehicle emissions testing only in 2 counties. I happen to live in one of them. I have 3 cars, and all 3 are registered in a non emissions county. I get a great sense of satisfaction from beating the EPA. I have been a car enthusiast all my life, and have had nothing but trouble with the EPA. Time to get even. But, nobody notices that. When somebody sees someone riding irresponsibility/recklessly on a motorized bike, they notice. If you get stopped by a cop, he knows how to tell if you have an illegal engine. And while the government does not have the Constitutional right to do a lot of things, they do them anyway. Look at what CA has done to the 2nd amendment. They can do away with the right to ride motorized bicycles as well. Not legally, but they can do it. Then they could impose heavy fines and even jail time for anyone caught riding one. It's a no win situation. Best thing to do is get out of CA
     
  18. CrazyDan

    CrazyDan Member

    Yeah I'm sick of how much gov wants to control my life, when I hurt nobody... I don't agree with my public servants treating me as a criminal each time they interact with me, with no suspicion of a crime occuring. In the words of Thomas Jefferson: a man that chooses security over freedom deserves neither.
     
    Sohighlyunlikely likes this.
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