has anyone seen this?

Discussion in 'Motorized Bicycle General Discussion' started by sojudave, Nov 23, 2008.

  1. xPosTech

    xPosTech The Old Master Motorized Bicycle Builder

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    I guess I'm not the only one dreaming. :rolleyes:

    Check out fan patterns for lacing the wheels.

    The only dwell extenders I'm familiar with was way back in the sixties. I built one for my Goat in '68. It just electrically closed the points a few milliseconds after they opened. It extended the dwell time that the coil had to build flux. The coil only built flux when the points were closed.

    The maximum flux is the saturation point of the magnetic coil. Sorta like charging up a capacitor. The more time the coil has to build the charge, the hotter the spark.

    This was an 8 cyl. engine with one coil. I'm not sure a 3 cyl. would benefit that much if it used points and coil. A single wouldn't benefit (unless it ran some ungodly RPM).

    The radials used magnetos. They also didn't idle. No throttle. Wide open or off.

    I'm not aware of any dwell extenders that directly/intentionally vary timing. The reason that "old" ignitions had a dwell adjustment was a dynamic setting of point gap. The wider the gap, the shorter the dwell time. Instead of specifying point gap, high performance engine manufacturers specified dwell. The lower the dwell percentage the cooler the spark.

    The dwell also affected timing to a slight degree (heh), but it was largely a mechanical/electrical delay for the points opening causing the coil flux to collapse and the spark plug to fire. The relationship of the plug gap and point gap also affected it.

    The wider of the two determined actual fire time. It also minutely delayed timing. If you have a stout enough coil, you can narrow the gap(s) and advance timing slightly.

    This was about or a little after the time MSD developed their ignition. The CDI (and electronic flash for cameras) about the same time or a little before. And dwell extenders became . . . moot.

    This is all from memory. I was just gonna mention dreams. Y'all can gargle and see how wrong I am (again). :(

    I need more caffeine. [​IMG]

    Ted
     
  2. eDJ

    eDJ New Member

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    FinFan wrote:

    Recently Deacon experimented with running a string trimmer motor on one of his builds in this way. Probably four months ago now. But when he came to a stop the engine would die and to start out he would pedal until the engine started and then throttle it. It was a friction drive set up and what I'm talking about would have similar characteristics to a friction drive. (but in what I'm talking about the crank would be bolted to the bike and the motor/wheel recropricate around the crank and piston array. I'm just guessing that at low speeds the engine would be set to lose it's ignition by design. The chain drive from the pedals would work similar to the free wheel on a 10 speed so that when pedaled up to a certain speed the ignition would engage and propulsion would ensue once again and the rider not have to pedal. In my scheme the carb could be throttled but if that wouldn't work then there would have to be a system there the ignition is set to progressively engage one cylinder, then two, and finally three in order to create a progressive power
    curve for the bike on acceleration and similarly on deceleration.

    As to the Dwell Extender, I was just a kid when Grand Dad purchased this little $9 dollar kit from Lawfayette or Onterio electronics to install on Grandmothers little 64 Opel Kadet station wagon with a 948 cc 4 cyl engine.
    It looked like the body of a C cell flashlight without the flared end for the reflector and light bulb. The tube was an annodized aluminum body with small extruded ribs which was provided with a couple plastic end caps with mounting feet. The small circut card inside had Grand Dad soldering an SCR diode and a bunch of other components to it. Very simple affair. He did work for ever playing with point settings and ignition timing and each time throwing me in the thing and with him and driving it around. He kept a small note book
    recording the settings and notes on what he thought he was getting from it.
    I remember he had a magazine like Mechanics Illustrated with an article abot the dwell extender where they tested theirs on the 4 cyl and a big 8 cyl and
    offered their views and feedback.

    xPosTech, I am so glad you explained all that and if it were up to me I'd edit some of it and make a Classic Sticky with it.....the explanation of dwell and pont gap influance on timing etc. Good basic nuts and bolts info.

    I was just a kid and remember grandmother grumbling how she wished he'd leave her little car alone whatever he was doing to it. She couldn't see any difference in the way it ran excepting that it had a little better "take off" as she would call it. Of course I couldn't say anything about what I heard either of them saying. I used to laugh at how small the motor in that Opel was though as it was about the size of grannies sewing machine. But the little Dewll Extender stayed with it till it's dying days when the transmission finally
    went out. It had a little top shifter 4 speed.

    That was my only experience with a Dwell Extender. I was wondering if there was any applicability to the concept today with a Gnome cycle motor.

    As far as the lacing of the wheel spokes I guess that should wait till the motor is actually thought out. In one old photo I once saw there was a dish used in place of spokes where the motor was nested into the dish thus giving a solid
    wheel form. If that creates the aerodynamics of a crude airfoil, it may lead to
    a more accelerated over the motor at speed. Perhaps that's what they were thinking back then. What's running thru my mind is to vent the exhaust thru holes in the dish and configure the timing of exhaust release so it would happen at the 4 o'clock and 8 o'clock position when looking at the dish side of the wheel. (thus keeping the exhaust low to the road or aft of the bike if the motor wheel is used in the rear. So the exhaust would occur between the 4 o'clock and 6 o'clock arc of the circle and the 8 and 10 o'clock position. The rear fender covering the tire may be cut at the 10 o'clock position to keep exhaust overspray off the bike.

    I know it all kinda seems hair-brained but if such a system were offered commerically, the frame dropouts would have to be replaced with the specialized ones I described. The electrical "kill swithch" would come out of one side of the axle where the mag is and the carb intake thru the other side of the rear axle. I'm wondering about a reed valve with the carb too.

    But this kind of "dreaming" or "Imagineering" is what we Industrial Design people do for Sales who in turn present it to the Design Engineers. Otherwise we take what Sales gives us and style it up sexy so people will go "ga-ga" over it and buy it. (a problem such as we've seen in this thread is that some
    producers come up with half baked products and want to go running off to design houses with them to get them sexed up for investors or market.... before they have a proven viable/dependable product to offer)

    As far as a rear brake a disc may be most practicle as it would be out of the exhaust spray fog.

    I think something like this could work and there may be a market for it with some. It would rely on high quality and dependability with low maintenance.
    And should probably be buit in Germany....so it would be sure to have the craftmanship to assure that.

    What would such a thing sound like.......I would rather imagine it sounding like a pressure cooker and 3 cyl motors seem to be inherently noisy.

    Driving it.......probably similar to any other bike except using the kill switch of some form to control the speed or have a governor that could be set for a top speed to comply with limits. This if the carb has to run wide open with a diaphram chamber atop the carb in order to allow the slide to throttle itself.

    But these are just my musings. :)
     
    #42 eDJ, Dec 4, 2008
    Last edited: Dec 4, 2008
  3. leftywoody

    leftywoody New Member

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    am I seeing this cad movie correctly ? Are the valve stems passing through the piston ?:eek:
     
  4. Creative Engineering

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    Yes you are, ingenious eh?rotfl

    Jim
     
  5. Creative Engineering

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    For an even bigger laugh go back and look at how the valves are opened and closed.rotfl

    Jim
     
  6. Creative Engineering

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    Even if this design were to actually fire, it would be a can full of cobbled up junk within seconds.

    Jim
     
  7. leftywoody

    leftywoody New Member

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    it looks to me like the area the valve cam lobe travels in is rather thin and the actual combustion chamber is rather small for any kind of true hp .:eek:
     
  8. Weedylot

    Weedylot Angry Old Fart

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    I had to post this thought, forgive me if I'm only slobbering on the pillow.
    Could a two piece rim separated by a centrifugal clutch assembly be possible? The outer would be only a rim, spokes and tire. The inner would contain all the goodies.
    Would this allow an idle? Sometimes I get confused, especially after imaginary CAD stuff...
     
  9. Creative Engineering

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    If you look at the blocks that the valves are attached to...There's nothing there to provide any kind of support. It looks good in the animation, but in reality these blocks would "whip" and bend the valve stems almost immediately.

    Jim
     
  10. leftywoody

    leftywoody New Member

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    I watched the cad movie on the assembally process .
    It looks at best impossible to get hand tool clearance into some of the areas to tighten the top end down at the combustion chamber, and possibly other areas . I see what you mean about the blocks . Maybe this could be marketed as a high class small boat anchor .
     
  11. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Yeah, it's a bunch of crap. (tech. term)
     
  12. eDJ

    eDJ New Member

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    The two piece rim/centrifigul clutch is an interesting solution to effect an idle.
    I'm sure that with some thought there could be a way to do it. I'm just wondering if the way to throttle the engine would be thru the carb or the sequencial ignition to fire the cylinders as a hit and miss. Running on one cylinder and then bringing in the other two once under way.

    When I was at the Wright-Patterson AFB museum I noticed several early aviation engines had valves with open external springs which weren't activated by any mechanical linkage. Just the vacuum or external pressure caused it to open and close. It was the first time I had ever seen such an arrangement. I'm sure the valve in piston worked that way.

    As a matter of fact that powered pogo stick of mine (the PopRod/PoGoGo) uses a poppet valve in the piston.

    I'm figuring a 3 cylinder radial with 20 to 25cc cylinders (like a small string trimmer motor) would sit within a 12" diameter circle on a 3.5" wide crankcase. So there could be room to construct the rim within a rim.
    I'm thinking of that mono wheel motorcycle set up on a smaller scale.

    With the two piece rim & centrifigul clutch configuration, it may take some thought to find a solution for manually locking the two parts of the rim so the bike could be pedaled...as otherwise only the center portion of the rim containing the motor would be connected to the sprocket chain.

    Any thoughts on that ?

    Photo of the mono wheel motorcycle below.

    [​IMG]
     
  13. Egor

    Egor New Member

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    It is hard to figure out exactly what this thread is covering. The Revo Wheel is just a small two stroke in a wheel. It is so small that it is easy to start just pedal. Everything is contained in the wheel, I guess it got expensive, as it never got to market. The interesting one is the engine in the vid. There are no dimensiones for that engine so it is hard to tell if it would work. One thing is the piston is only for moving the fuel air mix to the combustion chamber. That engine is so complex that I suspect it is not efficient. the Wankel engine is far less complex, again so dirty running that it needed an after burner. I doubt that the cam would last long,(the thing in the middle of the crank) and cooling would be a nightmare. It is fun to see another method of internal combustion. I doubt it would.wee..wee. make it to market, even with all problems solved. Creative Engineering has information in the form of computer rendering to figure Thermodynamics, I'm just an old motorcycle mechanic. All they let me have now is a hammer, screwdriver and a file. Have fun, Dave
     
  14. Upshifter

    Upshifter New Member

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