Are 2,3 or 4 engine motors better than 1???

Discussion in 'Motorized Bicycle General Discussion' started by Roadkill, Feb 17, 2009.

  1. Roadkill

    Roadkill New Member

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    How many do you have on your rig? Jet bikes have 2 sometimes.

    Today a good friend was telling me that I should not use more than one motor on my
    friction system that I want to build this spring or summer. I was thinking as another member here stated that one in the front and one in the rear would work better than just one alone. He thinks that
    would be like jet planes and need to sync the motors the same. Sorry for poor English I am in a hurry.
    He thinks that one motor will pull fine and faster than the other or slower and one will just spin even slightly spin out on the tire trying to slow down or keep up with the opposite motor. I am confused as people here have dual engines and even Large Filipino has a 4 wheel drive I think??

    Here is where I beg for usage reports eg: "Severe tire damage" or other strange happenings.
    Any photos and please how to hook up throttle linkage to more than one engine using special tools and tips on linkage wire?

    First I want to build the beast and fly down the trail.. Then I want to worry about brakes for the monster... I think I will double up sets and tie cables together and have 4 pads to a rim. Be safe!

    .fly
     
  2. Large Filipino

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    I got a FRONT wheel drive! Yea. I would imagine there would be a tug of war going on between multiple engines. Unless of course you can make the drive sprockets freewheel. Then you can use either engine for just cruising and two engines for pulling. The worst that can happen with a freewheel setup is that one engine is spinning needlessly while the other one is taking up the load.
     
  3. Roadkill

    Roadkill New Member

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    I thought I saw a post about a four wheeler.. Must be an ATV.. Thanks for the input.

    "Then you can use either engine for just cruising and two engines for pulling. The worst that can happen with a freewheel setup is that one engine is spinning needlessly while the other one is taking up the load."

    Yeah that is what I thought.. One would be just spinning unless an incline happens and then I IMAGINE that they would both be pulling together...

    Thanks LF .. and to everyone else as well.
     
  4. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    In most cases a single motor is better than one for putting around.

    I have a pair of 2.2hp Mitsubishi engines on Staton friction drives on "The Dragon Lady". Front roller is 1.25", rear spindle is 1.5". These engines are independent of each other. They do not need to be synchronized or run together. However there is less resistance drag and obviously more power if both motors are running.

    (On "The Iron Dragon" it has the same engines w/front friction drive and Staton rear chain drive w/18.75:1 gearing. However, it has less undesirable resistance issues because of the chain drive.)

    There is a very significant amount of resistance drag when both engines are disengaged om "The Dragon Lady", especially when walking or pedalling the bike. At slow speed you might have to stand up to pedal on level ground.

    Of course this is easily remedied by lifting the roller(s) off the tires. Then the bikes would pedal easily, even with the extra weight of two engine assemblies.

    The rear engine suffers the most from resistance drag when the front engine is idling. To overcome that I devised a lever which would lift the friction roller off the front tire when the engine's clutch was disengaged. It worked well but I rarely used it because both engines were engaged and disengaged so often.

    When I removed the front engine of "The Dragon Lady" to replace the friction roller, I noticed that the bike's low speed handling was much better. With front engine you have that extra weight hanging offbalance to left side. That's a problem inherent to front engines, especially if the engine is not centered on its mount.

    There was less friction with front engine missing. The rear engine could work better with its 1.5" roller. There was less weight on the bike and the low-speed/walking speed handling was significantly improved.

    Once the bike gets under way, the bike's unwieldy front end is not a handling issue. It is like having a supercharger providing MORE than 100% extra hp at any speed. I'm saying that more than 100% power is available because one engine's friction roller is smaller. That engine develops more hp/torque at any speed because it's spinning at a higher rpm than the engine with the larger roller.

    If traveling at 25 mph using the rear engine, when you throttle the front engine you're adding an extra 2.2hp and neither engine is being pushed beyond its normal limitations.

    Using two engines with identical oil/fuel ratios has less problems when installing an auxiliary fuel tank. I mounted a Happy Time tank on the crossbar of the men's bike("The Iron Dragon") and the downslope bar of "The Dragon Lady". Both engine tanks are replenished by the aux tank and fuel capacity increased by 100% per engine.

    Contrary to popular belief, both engines don't have to be synchronized or used together. Each has their own throttle. On "The Iron Dragon" I start off using the rear chain drive to minimize front tire wear from friction roller. Once rolling, any combination of engines can be used. (Of course the one I like best is both engines running at all times.)

    I am in the process of changing front friction roller from 1.25" to 1.375" size. Front engine is screaming at top end; the larger roller should save the engine and allow higher top speed.

    Because two engines are being used, no significant loss of power should be noticed at low/midrange.

    When caught in a continuous downpour six miles from home, I disengaged the friction engine and used chain drive to motor home safely.

    Also, when one engine konks out, the other one brings the wounded bike home at 20-25mph..rd.

    If each engine was running on the back wheels of a trike, then they would need synchronizing.
     
  5. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    That one engine is not spinning needlessly with a freewheel setup. It is disengaged and idling.

    By "tug of war" I'm presuming you mean "resistance drag". That disappears when both engines are engaged.

    If you full throttle the engine with 1.25" roller for a few seconds then release that lever and stab the other engine with 18.75 gears, it feels and sounds like you just shifted gears!!!

    There is a substantial drop in rpm from one engine to another. Since both engines are identical they sound the same.

    Sounds like shifting gears..shft.
     
  6. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Worry about your brakes BEFORE!!!!! you create the monster.scratg

    Think about installing front disc brake.
     
  7. mabman

    mabman New Member

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    Ask this guy?
    2d30cc8d1ecef2f6a9.jpg
     
  8. Mopedamauter79

    Mopedamauter79 New Member

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    How on earth does he keep the bike upright...then you got the fumes from the engines in your face and the noise...
     
  9. Roadkill

    Roadkill New Member

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    Some mufflers are longer than others.. Who knows.. But good point.

    I would venture to say 57 still has intellect even if "The Dragon Lady" is a major brain power depleater. If that is the case than you have myth busted the theory exhaust fumes case severe brain damage. I am all excited and want to weld and destroy my eyeballs with flashing arcs of madness.. I should also add my old Bronco with the read window down would draw fumes back through the cab.. A major flaw. I never really had problems on motorcycles and would imagine the rushing air would arrive faster than fumes could especially if the muffler is pointed downward blasting down or modified to do so.
    Thank you MM79 and all for this discussion.

    .trk
     
  10. Roadkill

    Roadkill New Member

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    Oh shlitz.. I missed that one! I need a drink.

    :-||
     
  11. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    .dd.

    "The Dragon Lady" is NOT a major brain power depleter.

    The front engine's exhaust faces left; exhaust pressure pushes the fumes outward. I do not detect any fumes coming my way, even at idle or moving.

    When I installed an expansion pipe for a day, the fumes DID blow directly onto me. I had to move the pipe to the rear engine because of carbon monoxide poisoning.

    To keep the bike upright I tie one handlebar grip to the seatpost.

    Because the suspension fork raises the front end, the stock bike stand won't work. Need to get a Whizzer stand.
     
  12. Roadkill

    Roadkill New Member

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    Great.. I think you are very insightful. What would you recommend for someone pulling a trailer full of people (little kids)? They might be far enough back so it won't really matter much but thought I would ask anyway. I guess there must be some serious pull to the left or right with more than one motor for you to have to have grip on the seatpost? That is where I get confused. No matter experience will kick my donkey soon enough.

    thanks again 57!
     
  13. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    LOL, Roadkill the "reins" from right-side handlebar to seatpost is only when parking. It keeps the left-heavy front fork from cocking and tipping the bike when parked. After "unhitching" the twin-engine monsters I wrap the "reins" around the HT gas tank's filler neck and away I go.

    I presume that a front-mounted engine would blow less fumes directly to the rear than a rear-mounted or frame-mounted motorized bike. I really don't know.

    For me, I have a spare front-mounted electric hub from an earlier project. I'd use that to pull a kiddie trailer. .crt.
     
  14. Roadkill

    Roadkill New Member

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    Ahhh cool.. I think you mean a wrap around counter weight. I guess balance is a good thing. Ooops.

    I was using electric stuff last year and untill the magic super cunductor capacitors land in marlboro cigarette carton sizes I am going to opt out of that situation.. I was popping chains and overloading and burning out motors last summer..
     
  15. ZnsaneRyder

    ZnsaneRyder New Member

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