Two 66cc engines side by side?

Discussion in 'Motorized Bicycle General Discussion' started by Smorkmo, Nov 18, 2011.

  1. Smorkmo

    Smorkmo New Member

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    I am thinking about building a custom mounting plate for my bike that is extra wide and mounting two, 66cc performance modded (port matched, milled heads, same length exhausts and expansion chambers, boost bottles, maybe nitrous, that sort of thing) china girls side by side. both drives would be connected to one 1/2" round tempered steel bar with good bearings. The drive bar would then be connected via chain to the right side drive of the back wheel, thus allowing for a disk brake in the rear on the left side. This bike would no longer have pedals. I'd use a beefy double walled rear rim with good spokes and steel eyelets where the spokes meet the rim. I'd use a Y-split and larger hose from the gas tank to the large bore carbs. A Y-split and custom bearing rollers to pull both clutches at once, both adjusted to engage the same.
    I only weigh 140 lbs but with the extra weight of the extra engine I will probably have to gusset or reinforce the triangles of the main frame. I'll use a springer front end and I have a custom made bobber seat for my tooshie. I'd probably have to use a 4130 chromolly steel axle for the rear so as not to bend it. Handle bars turned down cafe' racer style, and everything painted black with red trim. What does everybody or anybody think that the problems I may encounter will be?

    I've been thinking about buying an extremely expensive compact wankel engine and using that with a belt drive but then my a fore mentioned idea occurred.we..we..we. to me and I was like, "well that's a heck of a lot cheaper."
     
    #1 Smorkmo, Nov 18, 2011
    Last edited: Nov 18, 2011
  2. rustycase

    rustycase Gutter Rider

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    A major selling point of the chinagirls is they are cheap to play with...
    We like fun builds here.
    Pls post lots of pics!
    Have fun
    rc
     
  3. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    I also toyed with twin China girls idea too. I bought the engines and two OCC chopper motor mounts. The mounts were trimmed and were meant to bolt onto a universal mounting plate. The engines were side-by-side and 1/4" apart from each other. A common jackshaft was to connect both engines' drive chains. Then, a jackshaft sprocket would connect to the rear 36t sprocket.

    i scrapped the project because it was too wide. Also there were too many engine controls, two throttles, two clutches. Looking back in retrospect, the chopper motor mounts would need heavy gusseting. Vibrations would've been horrendous.

    I'm glad someone else is trying to build twin Chinas.
     
  4. richirich

    richirich New Member

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    Somebody has done the double motors, somewhere on this site i have reacently seen one while surfing threads. i do remember that it is a red bike and was flawlessly built.
    I wish i could remember where i had seen it though, maby someone else that has seen it and knows where its at will let you know. it is an impressive build.
     
  5. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

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    Bigboy has already made a twin engined bike using two 50 cc's

    Bigboy's "Double Trouble" was a show stopper at the Grange race on Oct 22nd
    along with their other two 4 stroke bikes.

    You had to be there to experience the evil sound those two motors made.

    [​IMG]
     
  6. richirich

    richirich New Member

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    Yep, thats the bike i saw... simply awsome!
     
  7. Smorkmo

    Smorkmo New Member

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    That is one seriously sick lookin bike!! I can only hope to build one half as nice as that. Mine will probably not be so elegant, but it will be awesome none the less!
    .shft.
     
  8. rohmell

    rohmell Active Member

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    Perhaps you can eliminate the dual clutch cable mess by using centrifugal clutches on both engines?
     
  9. dakota47l1

    dakota47l1 New Member

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    i would love to see more pics of this bike!
     
  10. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Sadly, the engines become even wider then.:-||
     
  11. Smorkmo

    Smorkmo New Member

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    True, it would probably be nearly 3 inches wider if not more if one were to use centrifugals, though I'm not planning on having pedals, merely nice pegs so maybe centrifugals would work. It would deffinately eliminate the clutch cables, but to be honest I have no experiance with the centrifugals so maybe that would not be a good idea for me.

    I would like to find a way to drive the motor on the regular gears of a mountain bike so that maybe I could have a shifter similar to a jack shaft kit but without routing it through the crank first.

    I live on the Duck Valley Indian reservation right accross the street from the police station and I know them very well. They never mess with me here. When I lived in Boise, Idaho it was a different story, got stopped every day. I have fought over $850 in tickets and citations and won every time. I was glad I won but I would have much rather had them just leave me alone.

    I suppose if I build it and take it off of the reservation then I'd have to get it licenced and registered in Elko, Nevada.. 100 miles away haha. Maybe I could ride it there :)
     
  12. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    If no pedals are involved, then having wider engines shouldn't matter. That solves a LOT of issues. Unsure of the quality of centrifugal clutches out there, tho.

    You MIGHT get by with one centrifugal clutch and one standard clutch. That way, you could pull-start the first engine, which would spin the jackshaft and "kick start" (not pedal start) the second one. Or pedal start the second engine, pin the clutch and pullstart the first engine.

    Orrrr, you could run either engine solo, or pedal the bike with both engines off.

    As long as you have room in the frame, it should be easy enough to install a jackshaft. What I would do is look at the SBP 4-stroke jackshaft/shift kit. SBP has a bolt-on flat mount and built-in j-shaft for the 4-stroker. If your twin-China mounts can bolt onto the SBP mount and align with its built-in jackshaft, then everything will line up with their shift kit. The shaft itself might have to be placed with a longer one. Short chains from engines to jack-shaft would be needed.

    What an EXCELLENT project!dance1
     
  13. thegnu

    thegnu New Member

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    how about this to eliminate some trouble fab a single carb to a y shape manifold, operate the dual clutches with a hydlaulic slave cylinder out of a stick shift toyota pickup an link the clutches like a dual 4 barel carb with threaded bar an heim joints that way you can still adjust them individually this way getting both motors to run in sync is much simpler. just my 2 cents
    Gary
     
  14. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    There will be times when the rider might want to run either engine, but not both, ESPECIALLY with engine trouble on one.

    I ran twin engines on a bike. When one crapped out, I could always "limp" home at 30mph.
     
  15. thegnu

    thegnu New Member

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    was just bouncing through 1 last time looking for interesting reads , I missed the part of being able to run each individually , my head goes straight to " BIGGER + BADDER = BETTER !"
    Gary
     
  16. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    That's the absolute best part of running twins.

    If one engine fails on you 50 miles away, the spare engine brings you home.drn2
     
  17. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    FWIW, both engines don't have to be synchronized. It's safer to have independent controls. Both engines don't have to work equally hard; one can be WOT, the other can be idling, if it has a centrifugal clutch.

    One time, I had the front engine with a lower gear rario than the rear engine. The front was screamling redline, while the rear engine was several hundred rpms lower. Both engines ran well. Sometimes the front engine rested while the rear engine pulled at highway speed.

    Twins are hella fun! I also have a twin-engined project I'm working on.xct2
     
  18. thegnu

    thegnu New Member

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    All I can say is I am on to watch this build an yours so please post lots of pics twins sound like a challenging build an I have just got to see it done .
     
  19. culvercityclassic

    culvercityclassic Well-Known Member

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    The sound of that bike made the hair on my neck stand up... It was the chit.. Great build
     
  20. Smorkmo

    Smorkmo New Member

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    In the pic of the red side by side, anybody know what that round bulbous tank is on the bike? If I didn't know any better I'd say it was an oil tank.. Does he have it set up to mix his gas and oil for him allowing him to just put straight gas into the main tank? How would one go about doing something like that and if one did how would one be able to guarantee that the mixture was consistently what you wanted it to be?
     

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