Two engines, one bike

Discussion in 'Rack Mounted Engines' started by kenspice, Nov 25, 2007.

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  1. kenspice

    kenspice Guest

    I looked through the FAQs and did a search but could not find anything on this subject. Has anyone experimented with two rack mounted engines, front and rear wheels? It brings up all sorts of possibilities. An engine assist engine, small engine for street, bigger eng. for trail-off road use, added power for hauling loads or trailer, spare engine for long trips or back country traveling, could have the belt disconnected on one to stay in compliance with cc limits and can still pedal, less wear and tear on spokes if both wheels are driving, two completely separate systems so a complete set of spare parts would be available. I don't know how each engine would act if assisted by the other engine or if this whole scenario is even possible and that's why I'm asking about this. Both could be belt driven or friction/belt combo. Each could be geared differently. One engine could be left idling when in hilly areas to be used when needed. Are there any pros or cons or additional ideas? I am a 71 year old hunter and this would be extremely advantageous for me as I need extra equipment and often travel alone.
    Last edited by a moderator: Nov 26, 2007

  2. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Hey Ken,

    A fellow member mentioned a tandem project a week or two ago. I'd recommended running a 25cc ROBIN or HONDA 4-stroker up front. I'd also suggested a 2.2hp MITSUBISHI for the rear, but a 32cc ROBIN/HONDA 4-stroke makes more sense. Both engines can feed off the same auxiliary tank.

    While cycling uphill and on the trail with a full load, twin engine drives would come in handy. This is especially for a senior citizen pulling a trailer for the deer you shoot.

    If both drive systems are same, like STATON or GEBE, one set of tools and each drive system being spare parts for the other drive, like you mentioned.

    If you choose STATON'S gear chain drive with reverse gear, you could be charging your camping gear's electric batteries while riding to your camp grounds.(Reverse gear could be rigged to drive an alternator.)

    sounds do-able, and practical.

    Last edited by a moderator: Nov 25, 2007
  3. JemmaUK

    JemmaUK Guest

    I like the idea of a twinnie bike - stanton or gebe would work well in that situation.

    Personally I would use the front engine as the main one with the second rear engine as secondary... FWD being more efficient that RWD..

    There is one issue that worries me however considering the rider and the activities is the range of the machine... and its not that it wouldnt be capable its more what *could* happen in the situation of an accident or incident..

    If we assume a flat road range of 60 miles unladen ... the we can assume 40 or so miles maybe as a cross country range... so what happens if there is some sort of serious problem ... even without a aux tank you could be 20 miles plus from the road...

    having a bike die when you are on a road in the UK in most cases is nothing more or less than very annoying and frustrating...

    having a machine die in the middle of a forest or there being an accident could be a whole lot more serious... I wonder if in some situations the very ability of these machines might be a double edged sword...

    Jemma xx
  4. kenspice

    kenspice Guest

    I forgot (sorry about that) to mention that I already have a rear mounted GEBE R/S 35 and was thinking about another 35 or maybe a Tanaka 40cc two-stroke on the front. If I go with another 35 on the front I could carry a gallon of reg. gas with me and not worry about mixing. With the Tanaka I could carry a half gallon of reg. and a half gal. of mixed. My big concerns are has anyone tried this? Did they work together ok? How about two separate gears (one trail, one road gear) either one could be used as the main engine and the other, idling, used when necessary. I don't think the speed would change much but the power should be improved at low speeds. Is that correct? Thanks Myron and Jemma for the quick response. I have only had my 35 a few weeks and am extremely happy so far. It's a good set-up.
  5. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Ken, I think you could go to ROBIN 25cc for the main engine, and make your 35cc the backup powerplant.

    Both engines feed off the same 1-2 gallon auxiliary tank, mounted midframe. No premixing needed. Simply cruise into the gas station, and fill all THREE tanks.:shock:

    That'd be a sight to see!

  6. kenspice

    kenspice Guest

    Right, if the set-up works! I will have about $1700.00 invested so I would like to hear some more about any problems I might encounter. Am I the first to try this? Engines, belts, clutches should all last longer. Since both wheels will be pulling during hill climbing and heavy load periods, the pressure will be on 72 spokes instead of 36 so they should last longer also. The more I think about this the more enticing it sounds. I weigh in at about 200 lb.s + extra gas + extra engine weight = two 35cc's may be the better choice?
    Something else, when doing my everyday runs over flat country, I can disconnect one belt and tie it out of the way. This keeps me street legal as an under 50cc bicycle. The other engine is a "spare". Off road or in the woods, who cares? I can travel on logging roads as a bicycle where cars and motorcycles are not allowed, such as closed gate areas. Tie BOTH belts out of the way and I AM a bicycle. Any thoughts on this?
  7. gone_fishin

    gone_fishin Guest

    my only thought...matching and synchronized front and rear...2 GEBE tanakas would rock my world...great topic :)
  8. kenspice

    kenspice Guest

    By the way, Jemma, "Twinnie" is a good name. Thanx. Or "Double Barrel", Etc. Etc. My wife (Japanese) calls it "Mondai" - Trouble.
  9. kenspice

    kenspice Guest

    Augidog, I think Syncing them would not be necessary as both engines would be assisting each other. Think of it this way. I am on one engine and the other is idling. I come to a steep hill and when I get too slow, I ease the second engine in. If I am right BOTH engines should speed up? I hate to spend that kind of money just to find out I am wrong....
    Last edited by a moderator: Nov 26, 2007
  10. gone_fishin

    gone_fishin Guest

    sure...just like pedaling and motoring, you can find the balance...however, you may be putting yourself in a situation where one drive outweighs (therefore negates) the other, and you find yourself using one or the other instead of both.

    imo, identical drives is the only overall-practical way to accomplish real dual-drive.

    EDIT: if i'm correct, it also means the weaker drive will be a drag on the stronger, making matters even worse.
  11. kenspice

    kenspice Guest

    Augidog, thanks for the input. I understand your point and it makes sense but when you are pedaling are you not then being another "engine"? Are you assisting the engine or is it vice-versa? Does either of you negate the other or do both of you speed up or ease the pressure on the other? This is a very interesting and important subject to me and I have absolutely no experience with it. I am trying to digest all of this info and it will help me make a decision. A friend has told me he thinks the two centrifigul clutches should make it unnecessary to sync the engines. Thanks again.
  12. gone_fishin

    gone_fishin Guest

    well, i wish i had the funds to experiment, and i don't envy you your research.

    while i believe the 2 centrifugal clutches would allow both engines to operate at the same time, i'm not buying that they'd synchronise themselves, power-wise...i think all that would happen is the slower/weaker one would only be making noise while the faster/stronger had the load. and, if i'm correct, once you've the attained engagement-rpm of the weaker one, then it becomes a drag on the stronger one.

    again, i think anything could be synched with anything, including the human engine. but humans are able to instinctively adjust, or synchronise, which is one of my favorite parts of this motorsport. i assist the engine, or the engine assists me, and it's my choice.

    so, you're saying you're willing to do the science (play with 2 throttles) every time you want dual, or triple, drive...again only opinion, but it sounds like pre-engineered trouble to me. and you haven't even begun to figure out how to make sure that your mismatched system will synch-up as pertains to gearing to tire-on-road, powerband/range, temperature, etc... heck, adjusting myself to the throttle-response of 2 different engines is enough to convince me i wouldn't bother if i had the choice ahead of time. like dog-sledding with a husky & a shepard, both good dogs but with entirely different sled-pullin attributes. now that i read that last line: even synchronizing the 2 dogs would be an easier task...they can learn to work together, while the engines never can.

    EDIT: what the heck am i doing up so late? everyone, it's been a GREAT weekend here on the board, thanks to you all. be continued :)
  13. gone_fishin

    gone_fishin Guest

    a new morning-thought, about engagement rpm: even when under one engine, it seems you have that extra drag of the dormant drive to work out yet.
  14. kenspice

    kenspice Guest

    Augi, glad you stayed up as your input is well taken. Point in case, I do not intend for either engine to be chasing the other as this would only happen if I were looking for speed. Using only one engine (the other is idling and this only in hilly country). As the main engine slows and begins to labor, I ease the throttle up on # 2. I think I would be able to feel and hear the main engine picking up more of the load until I could again return the # 2 to idle. I agree that at high RPM,s the weaker of the two would become a hinderance. During off seasons and flat roads, remove 3 nuts and the clip-on throttle and I'm back to one bike and one throttle. The whole object is to get my old body over the hills with a bigger load and only at low RPM,s. As far as temperatures go, putting less load on # 1 would lower the temp., Don'cha think? As far as exercise... I will have the strongest thumbs around. The other option, of course, is to take the 35 off during hunting and install the Tanaka and lose all of the advantages that I am dreaming up.
  15. gone_fishin

    gone_fishin Guest

    temp was referring to engine specs, 2 different engines would be affected in different ways by everything.

    throttling: one throttle would be fine if the drives were identical.

    man, please don't look at my input as discouragement...i'm being devil's advocate and engineering assistant rolled into one...please do go on :)
    Last edited by a moderator: Nov 26, 2007
  16. kenspice

    kenspice Guest

    On your morning thought- With the clutch of # 2 disengaged, the drag of it's belt should be almost negligable
  17. kenspice

    kenspice Guest

    Never one throttle. If I have to sync the engines I will quit this project. One main engine- the other is to assist on hills only.
  18. gone_fishin

    gone_fishin Guest

    you don't have to do anything except what you want to do :)

    i'm pretty sure you're thinking about this detail, and i should leave you alone now, but i look forward to watching this progress :cool:
  19. kenspice

    kenspice Guest

    Really Augidog, I appreciate your input and want more of it and others as well. I was only referencing the "one throttle" aspect. I think it would be much too difficult to sync 2 engines with one throttle to gain top speed. I just meant to emphasize that I am only interested in low rpm's on hills or heavy load conditions and to use the engine#2 only when absolutely necessary or as a spare. I also intend to get two GEBE built wheels if I deceide to go on with this. I love these Wa. mountains and want to see as much of them as I can.
  20. JemmaUK

    JemmaUK Guest

    lol ... I was thinking more along the lines of Kamikazi or 'divine wind' (the original by the way, not that of later connotations)... but mondai is good - reminds me of monday mornings..

    I think two engines of the same type would be better because they would have the same torque and power characteristics - and also if they have the same drivetrains there is less chance of problems (and no duplication of spares).

    As to your thought of syncronisation to get top speed I think there would be a way to sync the ignition systems by linking the low tension circuits of both engines although the mechanical details elude me (I have about as much physical ability with electricity as I have in playing rugby...)

    However, I dont think you will need to - because if you are roadrunning that will take care of itself quite simply. The problem with my little GEBE on Anita was that she would pull to a certain point and then the engine ran out of puff well below (at least I think so) the top RPMs of the engine. I am good with the sound of motors (telling which cyclinder wasnt firing on a straight 6 by guesswork at the first attempt... I got alot of looks from my ex's grandad who used to be a mechanic.. if he could see me now lol). The problem was that with the one engine the torque curve ran out before the engine hit top revs becase of the weight.... with two engines they can work off each other and will therefore be able to (sans LPA) get higher in their rev bands and therefore higher top speed...

    Thinking of Roadrunners ... wasnt there a plymouth under that name a few years back (aka before I was born...). I've seen the 402 M/Cleveland engine - that things bigger than whole cars here...!

    hmmm Mondai RoadRunner sounds pretty good to me:D

    But I guess your wife would happily kill me if I even mentioned dropping a 440 6-pack into a schwinn lol...

    Jemma xx
    Last edited by a moderator: Nov 26, 2007