HS 142-F reverse engine and SBP freewheel brainstorming...

Discussion in '4-Stroke Engines' started by bakaneko, Aug 19, 2016.

  1. bakaneko

    bakaneko Active Member

    Hello. So, just doing some brainstorming on an idea for a new possibly cheaper way to do a shift kit for a 4-stroke HS 142-F without the jackshaft. I am okay if this doesn't work or if the power lost in the system is too great.

    If you reverse the HS engine so that the drive sprocket is on the pedal sprocket side then the rotation of the sprocket is reversed and doesnt work. However, if you place another sprocket on top of the drive sprocket and utilize only part of the drive sprocket you can get the chain to run in the right rotational direction (see picture A).

    Now, with my new pocket bike transmission it seem like I can get the drive sprocket and SBP free wheel to match up either with the existing mount holes or drilling new ones. This is what it looks like reverse now (see picture B and C).

    Thoughts on this? Would love if Pablo can comment. Just doing some brainstorming.

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  2. Pablo

    Pablo Motored Bikes Sponsor

    Not sure you would get enough gear - chain engagement to drive the rotation.
  3. bakaneko

    bakaneko Active Member

    thx for the input. if i were to try this out, can you let me know what individual items that i might need from you? (freewheel, sprockets, axle?)
  4. Pablo

    Pablo Motored Bikes Sponsor

    Axle? Insufficient information at this time to provide a parts list.

    You should probably engineer it out a bit more and contact Jim for suggestions. Thanks.
  5. KCvale

    KCvale Motorized Bicycle Vendor

    Ya, Jim is a frigg'n genius engineer, he helped me with my design.

    The problem with doing it your way is getting enough gear reduction to the BB sprocket, and lining up the output sprocket with it.

    I have been trying everything (like you) I could think of and you know what I came up, the 10G long shaft transfer case...



    This is the best I could up with and it works like a charm, but if you come up with something even better I'm all ears!
  6. bakaneko

    bakaneko Active Member

    oke, thx for input guys. it is just a brainstorm at the moment, i will flesh it out a bit more and work with jim. cheerz
  7. Steven Main

    Steven Main Guest

  8. CrazyDan

    CrazyDan Active Member

  9. Frankenstein

    Frankenstein Well-Known Member

  10. FurryOnTheInside

    FurryOnTheInside Well-Known Member

    Not enough engagement, I think. As Pablo said to a similar idea earlier in the thread.

    I'm wondering why (or if!) a four stroke engine can't be made to run in reverse anyway? I mean apart from things loosening.
  11. Frankenstein

    Frankenstein Well-Known Member

  12. gary55

    gary55 Well-Known Member

    Build something similar to the belt drive. Directly engage gears instead of belts and pulleys to rev. rotation. Come off the big gear with a sprocket, and chain down to the free wheel bottom bracket sprockets. A slightly more involved trans. but no j shaft. Should save costs in the long run. With a good cent. clutch it would go well. With a manual clutch it would be awesome. Their is a crude concept of what you have to build to slap onto the side of a right drive 4 stroker sitting under the clutch cover of the china girl.
    Last edited: Mar 28, 2017
    FurryOnTheInside likes this.
  13. 5-7HEAVEN

    5-7HEAVEN Active Member

    Many years ago, a fella succeeded in doing that with a 6hp Robin engine, mounted mid-frame in a bicycle. He either posted it here or in "the other forum".

    Unsure if he used sprockets or pulleys. He placed a pulley/sprocket ABOVE the engine pulley/sprocket, SERPENTINE-style.

    To ensure sufficient engagement, you could install TWO sprockets/pulleys above and astride the engine sprocket/pulley.
  14. bakaneko

    bakaneko Active Member

    Hmm, I found this in the annals the rider reversed his engine to fit it into the smaller frame and not to utilized a SBP freewheel to use the right drive train. But, the placement of the roller is smart. I reversed my HS-142F engine with a normal transmission just to test and there is not enough clearance to directly engage the transmission sprocket for a reverse rotation and I thought other points on the bike too weak to handle the torque of the engine, but this placement seems like a good strong area (lotsa points for securing, seat tube, top tube junction) to be the focal point of the rotation reversal. Thx for bringing that up.

  15. KCvale

    KCvale Motorized Bicycle Vendor

    Well there ya have it...
    More examples of how NOT to get engine power to the right to use the bikes gears.
  16. Frankenstein

    Frankenstein Well-Known Member

    Other than the lack of gear down the design is awful. I mean awfully good. Not really...

    He asked how to flip is and connect the motor to the rear wheel, did exactly that and nothing else. I'll note your photographs weren't much better, they all had the driveshaft on the left side!
  17. Frankenstein

    Frankenstein Well-Known Member

    That looks cool, so I must ask how easy is it to just reverse a 4 strokes rotation? Way too easy on the universal 2 stroke but seems like it would be harder on one of those to a certain extent. Or would it... Is it all just in the spark timing I mean it's doing the same exact thing only spinning a different direction..
  18. gary55

    gary55 Well-Known Member

    Turn the seat around and steer from behind.
  19. CrazyDan

    CrazyDan Active Member

    I'm pretty sure the engine is beefed up in a way to handle the rotational stresses in one direction but not the other. You'll probably see failures at multiple points. Think about how many nuts/bolts are threaded so they tighten with regular usage but unscrew themselves if reversed. You'll have to reverse thread many things.
  20. Steve Best

    Steve Best Well-Known Member

    The spark timing, cam lob order/timing and any oil pumps or directionally oriented oil dippers/slingers/scrapers/baffles need to be changed. Timing is typically easy with a new flywheel keyway. The cam needs to be cut and rewelded (typically drilled for an alignment shaft) to reverse the order of the lobes and then retimed. Splash lubricated engines may need some thought where direction often determines top end lubrication, but most just rely on splash and mist so you may be OK.