Vertical crankshaft lawn mower engine on a bicycle?

Discussion in 'Rack Mounted Engines' started by Unregistered, Feb 7, 2008.

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  1. Unregistered

    Unregistered Guest

    i just wanna do this simply
    no clutch, not much money invested, on a mountain bike.
    im not even a hobbyist but my uncle kinda knows how to "mount" stuff..
    if i cant find a horizontal shaft engine, what do i do?

    and if i can find one, whats the best/easiest way of mounting it?
    i mean, let it spin the bicycle chain? the wheel (directly)? or with a wheeltop friction drive?
    i thought of it just being like mounting it on the side of the rear wheel axis, and let it turn the wheel directly..

    and what should i do if i can only find a vertical shaft engine?

    Thanks alot,

  2. HI,

    I don't know how easy it would be to adapt the vertical engine so that its output at some point becomes where the horizontal engine starts off at but if you look at an older DR field mower they take a horizontal engine and (through a single twisted belt) they make the horizontal engine act like a vertical engine to drive the could probably rig up some sort of twisted belt drive to power the bike BUT the vertical engine is most likely wider then the same HP horizontal engine so that may pose some problems with mounting the engine itself and being able to pedal.....May be easier to barter with somebody and trade the old vertical engine for a horizontal engine.

    Hope this helps.

  3. eltatertoto

    eltatertoto Guest

    i honstly have no clue lol but i found a great 6.5 hp side shaft on sale this week at harbor frieght, 130 buckeroos, if your uncle is a good mounter, that would be a kick butt engine to put on, the same price as a happy time. might try a weed eater with an all position carb, if you search davids farm on u tube he has a cool setup, and he did everything him self, im more of a bolt-on fan myself :)
  4. I was looking at riding lawnmower racing sites and had a pretty amazing brainstorm.
    If I can get a riding lawnmower transmission which is essentially all you need for it comes with an axle and hook up a lawnmower engine,then get some wheels and make it a pusher trailer it would be so fly.
    I mean,you can electric start the puppy,maybe cable down the gear shifter (GEARS!!) and with it being two wheels you can even cover the whole thing to look like just a trailer...until you push the start button.
    I hear some of those lawnmowers can go like 60 miles an hour!

    I got these pics from here:

    Attached Files:

  5. Scottm

    Scottm Guest

    I often dream of a shaft drive bike. Your vertical shaft could have a u-joint welded on and connected to a drive shaft to the rear axle. A mini BMW. Just dreaming.
  6. BoltsMissing

    BoltsMissing Active Member

    Shaft Driven Bike

    I read somewhere though, when force of pedaling has to change direction, some power is lost.
    So if ya pedal downwards, and the shaft has to spin 90 degree via gears, then another 90 degrees to spin the wheel, some power is lost in comparison to direct chain pedling.
    But hey, what are motors for ?
    If this type of concept can be added to a bike, then the engine's chain drive may be where the front pedal gear was, but on the left side ?
  7. fetor56

    fetor56 Guest

    Fantastic concept...dunno though how good it would be at standing up to abuse.
    The next time i'm around that area i'll drop in and maybe(maybe) they'll let me go for a ride...if not i'll take more detailed pics and ask questions.
  8. eltatertoto

    eltatertoto Guest

  9. Klox

    Klox Guest

  10. So I got this riding lawn mower at craiglist for free and it's a bonified way of running a vertical shaft engine for your bike if you make it into a trailer pusher. The only thing right now though is that that gearbox is so geared down that if I changed the pullys to get it back to speed it's gonna be spinning a whole lot inside there. Well I could always pack it with some gear lube.
    Here's the original thread:
    I probably won't use that engine. 6 horse is overkill. Pretty hard pulling anyway. I'm gonna scrounge around for a regular lawnmower engine hopefully with a key start.
    It would be a lot easier if I found a horizontal drive for I could do away with that tranny altogether but I want this to work.
    Stay tuned.
  11. eltatertoto

    eltatertoto Guest

    mabey this is a stupid idea (i really dont think it'll work) but in theroy if i tilted a mower engine on its side, and just repositioned the carb would it work ok? thanks cause in my trailer thread somone said (large i think ) thats a bonified way of making a trailer pusher, and i have an extra mower........ i think there would be issues with oil though
  12. WOAH! Okay. It will be top heavy,but with a welder,rack mount the vertical lawn mower engine,shaft pointing down and to the side,add a friction drive and have it swing outwards.It wouldn't have to swing out but maybe an inch so attach it to a cable and you have a clutch mounted to your handlebar. Add a spring strong enough to engage it when you release the clutch lever but not so strong you can't squeeze the lever to disengage it.
    I would beef up that tire,though. Your most definetly going to need a solid tube on that tire,and maybe epoxy or rubber cement or whatever would work a thick rubber layer on the side(a salvage tire maybe) so the friction drive won't wear out your sidewall. Or find a tire with a thick sidewall.

    I so need a welder. I already have that clutch engagement in my mind. It's gonna require a roller for the clutch cable needs to do a u turn for it to work right.
  13. mickey

    mickey Guest

    I believe you are correct on the oiling issue. A vertical shaft four stroke has its oiling designed for that attitude. I think that it will seize if run on its side for a prolonged period. (although, I have tipped my lawn mower through at least 70 degrees with it running, but that was only for a few seconds. hmm)
  14. eltatertoto

    eltatertoto Guest

    i doubt itll work, because if i just tip my mower 4 like 5 min to untangle a baloon string or a rope etc ( im lazy, and let the yard turn into a jungle lol) when i go to start it , there will be oil in the exhaust, and itll be hard to start, and when it does start, it takes atleast a couple min for all the oil 2 burn out of the exhaust.....the same thing happens, when i pop a wheelie on my minibike, if im ridin a wheelie, mid wheelie itll die, and ill have a hard time startin it, and then the oil in the exhaust burns.
  15. happycheapskate

    happycheapskate Active Member

    I have worked with vertical shaft conventional lawn mower engines as a lawn maintenance tech and DIY repair man.

    The engine can be tilted while running only about as much as a mower would get tilted when lifting to dislodge grass clumps or to turn the mower.

    If you tried turning the engine sideways, you will have the immediate problem of oil leakage, most likely right into the cylinder, fouling your plug and top of piston, possibly making it to the carburetor and leaking out.

    If you run a lawn mower engine and try to invert it or tilt it too much, it will stall because of this problem. Tecumseh will probably be the worst about it, and some Hondas and the fancier Briggs may tolerate quite a degree of tilting. But it will flood out after the engine dies.

    Remember also that 4 stroke vertical shaft lawnmower engines do not have as good a crankshaft bearing system (probably just one bearing) vs the 2 stroke Lawn Boy vertical shaft engines of yesteryear (outlawed by Kosherfornia and CARB and many stupid lawsuits).

  16. happycheapskate

    happycheapskate Active Member

    re: vertical shaft briggs moped

    I am plotting to build a powered bicycle with a 4hp old fashioned briggs with the automatic choke. I expect to mount a metal pipe along the top tube, extending behind the seat. A motor platform will be welded on that, or mounted so it can rotate to let the motor tilt about 25 deg. (spark plug upwards) and a small rubber wheel will be mounted on the shaft (Do the math, a small wheel at 1600-2800rpm will move pretty fast). The weight of the motor plus a stretch spring, will keep the propelling wheel or flywheel resting on the tire or sidewall/rim. A rubber wheel on a rubber tire should afford great traction and allow long wear.

    Lawn mower at high idle to 3/4 open throttle= 2000rpm as a given.
    a 5" diameter wheel should go about 30mph. If you are going to use a flywheel to turn on top of the tire, it would have to be 6-7" so it didn't fall off the tire (the outside wouldn't touch, like a record player with the needle in the middle.
  17. arceeguy

    arceeguy Active Member

  18. loquin

    loquin Active Member

  19. WhizBangAndy

    WhizBangAndy Member

    Now thats KISS in action there..Man i might try that with the 8HP Briggs I got in the back..I think I already have everything to make it too..Including a release handle from my office chair that just gave out. lol
  20. happycheapskate

    happycheapskate Active Member

    not exactly but thanks

    I like the design, but his drive roller is too small and I don't have any welding equipment. I will have to commission some college students to help me or someone with a welder.

    I want to try a design using a small metal flywheel that sits on top of the tire. It will scrub a little bit since the top wheel is smaller than the bottom and rotates nearly perpendicular to the tires rotation, but this should only marginally wear tires, which is much less of a problem if it is not wearing spokes by flexing the wheel too badly. (which your friends design also accounts for.)

    I can get bargain bin mountain bike tires with center raised tread for $8-15.

    For someone that mentioned an 8hp briggs engine. You are crazy! Either you will burn up your tires, or you will have steering complications from such a weight back there. And how will you kickstand a bike that weighs 80lb?