(posible project) Turning a bicycle into a motorcycle

Discussion in 'General Questions' started by bikejock, Sep 9, 2015.

  1. bikejock

    bikejock Member

    After looking at a few Predator engines I was thinking of turning a bicycle into a motorcycle using a 212cc or larger predator engine and making it go at or close to motorcycle speeds of between 60 to 80 mph.

    Here's a list of what I was thinking of using for this possible project:
    1: Predator 212cc, 301cc, 420cc, or 650cc EPA & CARB certified 4 stroke engine
    2: EZ Motorbikes Qmatic transmission
    3: (if possible) motorcycle gas tank
    4: Jackshaft shift kit (if bike has gears)
    5: all motorcycle grade lights like turn signals head light tail/brake light
    6: motorcycle mirrors
    7: motorcycle license plate bracket (probably axle mounted)
    8: motorcycle horn
    9: 12 volt motorcycle battery wired somehow to friction generator to power lights & horn
    10: good sturdy moped wheels with good brakes

    I think that's petty much everything I would want in this build. The tricky part is finding the right bike for this kind of build that can fit a large Predator engine. I'm considering a Felt for this project because I hear nothing but good things about them and they seem to have lots of space for bigger engines and some Felt bikes are within my price range. If anyone has any tips or suggestions feel free to chime in.

  2. jaguar

    jaguar Well-Known Member

    you left out fat tires and suspension front and back.
  3. bikejock

    bikejock Member

    Oh right. I should add front suspension although most Felt cruisers don't have front and back but I've seen plenty of Felts with front shocks. It would call for some extra fabricating to make rear suspension on the Felt I want and I'm trying to keep frame fabricating/mods to a minimum for this project if I start it.

    Fat tires might cause problems because of the chain clearance issues. I tried to get an MB chain on a bike with a 3 wide tire on my current 4 stroke bike but it was rubbing on that tire too much when I test pedaled it. If I drove it with the 3 wide it would have shredded the tire wall so I went to a 2 wide in the rear.

    I could probably find a way to addapt moped wheels that might have the proper clearance. I've seen motorized bikes with moped wheels before.
  4. butterbean

    butterbean Well-Known Member

    You can't use a friction generator at 60-80mph. Based on my experiences with them, I don't recommend using them at anything over 30mph. 35 maybe, but that's really pushing it. They get hot at 32. Some are of cheaper quality and can't even handle 30. Your best bet is to run a Kubota generator off a belt driven by the crank. I've considered going that route myself but I'm too cheap. I also want to mention, for what it's going to cost to build this kind of bike, you can get a used motorcycle. Hell, for what I've got in my current project I could have gotten a used motorcycle myself. The only reason I didn't is because I only want to go 30mph. There is seriously no advantage to having pedals on a bike that can do highway speeds. It's gonna be too damn heavy to pedal anyway.
  5. bikejock

    bikejock Member

    I should go with a 79cc or 212cc Predator to keep the weight of the whole bike down. I think to be more realistic I'll proababily try to get speeds of at most 40 mph. Wouldn't feel safe to be doing 60 on the highway on a motorized bike anyway.

    The reason I want to try to convert a bicycle into a motorcycle is because it would be easier to store and easier & cheaper to maintain than a motorcycle. It's also because I got other motorized bike projects planned throughout the coming year and more garage space means more room for other builds.
  6. 2old2learn

    2old2learn Member

    I built mine so I can put in in my trailer hitch basket and strap it down to the basket for transport. Ive done this with scooters but their weight makes them a bit dangerous to load and unload. I can just pick my motorized bike up and put it in how I want it to ride and strap it down and go.
  7. jaguar

    jaguar Well-Known Member

    the main advantages of a motorcycle is it's less noisey (if the motorized bicycle has an expansion chamber) and the ride is plusher (due to fatter tires, suspension, and cushy seat)
  8. butterbean

    butterbean Well-Known Member

    I consider my current project a light motorcycle. It's a 1956 Roadmaster with a 79cc predator, Suzuki K10 hydraulic motorcycle forks (bolt right up to a bicycle with existing headset), custom wheels (motorcycle drum in front, moped drum in rear, both laced to 24" bicycle rims with 11g spokes, laced and trued them myself), custom lighting/charging system I designed myself which includes LEDs front and rear with parallel circuits that give me high/low beam upfront and tail/brake combo in rear, charging system is friction generator wired to scooter rectifier. The bike is geared to cruise at 30mph, will hit 31.5 at 6k rpm, I won't rev it past that. Will spin 5700 at 30, gonna try to keep it there or lower. Have a tach and a speedo, so shouldn't be too hard to do that. But the reason I consider it a light motorcycle is because of how heavy duty it is built. It's built tougher than some mopeds. I set out to make this thing bulletproof, and its starting to look like I accomplished that. A few pedal rides have shown the wheels to be holding up pretty good so far. Got a few issues to work out with the intake and exhaust, so not ready to install the engine quite yet.
  9. bikejock

    bikejock Member

    Guess you could consider it a motor driven cycle which I think is the technically correct term. They are basically light motorcycles with an engine smaller than 150ccs and pedals are optional.
  10. butterbean

    butterbean Well-Known Member

    There have been motorcycles with engines under 100cc's. The Suzuki K series, which is the series my forks came from, were all 79cc single cylinder 2 strokes. Granted, they were 6hp and also had the advantage of a 4 speed gearbox, but going by displacement alone, anything over 50cc technically is a motorcycle. The only parts on my bike that are actual bicycle parts are the frame, bottom bracket and rims. Everything else is motorcycle or moped parts. The first motorcycles had pedals and were single speed. If you Google motorized bicycles, you can learn all kinds of things about the history. Compared to modern factory built motorcycles, my bike is not the same. But compared to the average kit bike, my bike is a light motorcycle. I geared it low because I ain't interested in going fast, just getting there. I could easily gear it to go over 40 if I wanted to. I still consider it a light motorcycle.
  11. butterbean

    butterbean Well-Known Member

    Oh and I the tires are bicycle tires. Forgot that.
  12. 2old2learn

    2old2learn Member

    Put it on some scales and let us know how it weighs in.
  13. Wolfie65

    Wolfie65 New Member

    Why not just buy a dirt bike?
    A bicycle (frame) going faster than 30 mph or so is a recipe for disaster if you're not a pro racer, and sometimes even then.
  14. butterbean

    butterbean Well-Known Member

    It will weigh between 85-90 lbs wet.
  15. HeadSmess

    HeadSmess Well-Known Member

    we dont always agree, but READ THIS POST!

    about the best advice youll get ;)

    one...headset bearings... the bicycle ones wont take the load unless you can find obsolete 28mm types. failure here = death
    two... gearing and such forth... a motorbike with out gears is simply awkward. and CVT systems are heavy, hard to design so they work effectively...yarda yarda...

    theres plenty of other issues but basically... get a motorcycle.

    your argument about storage is a moot point. a (little) motorcycle is far easier to handle. a pushy ends up being fairly wide with them pedals sticking out awkwardly...

    you also dont seem to have considered the total weight...unless you work in alloy, its going to be hard to keep it down.

    dunno what its like getting engineer certificates over there, but here...costs at least $500 to have it inspected and signed off as being "roadworthy". this is BEFORE any registration fees etc. insurance also piles up due to it being homebuilt, and theres the hassle of receipts and frame numbers, etc etc...

    or, you coooould keep on the idea of what youre doing...but select a decent engine, ie...get something off a motorcycle. lifan types may be cheap but they are ridiculously heavy... what you want is something like a crf/cbr 80-125... nice lil fourstroke with a gearbox that is lightweight and is virtually bullletproof...and requires to further work to get it up to spec.

    if you dont mind the buzz of a twostroke...you could get an old dirtbike engine, or a denardis/morini from the ktm 50 type bikes...

    the gearbox is the hardest part to get right... experienced?
  16. butterbean

    butterbean Well-Known Member

    Just wanna mention here, I know your post was directed at the OP but just wanna point this out....I'm using Suzuki k10 hydraulic motorcycle forks....1" threaded steerer tube, bolt right up to a bicycle with existing headset and bearings....not the first bike I have run this setup on....and as far as gearing, all depends what the rider wants....I'm geared to cruise, 30mph at 5700 rpms, I geared my bike for acceleration and climb, not speed....could easily gear it to do over 40....yes I do agree, if you want to do highway speeds, get a factory built motorcycle....if you just want to cruise at around 30+mph but want a heavy duty bike, you can do what I did, I described how I built my bike in another post in this thread. I think if you read it, you'll agree its built pretty tough. Granted, its a little on the heavy side at 85lbs, but with the engine I've got I don't think weight will be an issue at all.
    Last edited: Sep 13, 2015
  17. HeadSmess

    HeadSmess Well-Known Member

    agreed...even my 750 used a 1" steerer tube... but the bearings were slightly beefier than the standard bicycle bearing... not to mention the guage of steel used in the frame, the extra gusseting, la de da... its not just the bearings but that whole area thats a concern. sheesh, i can snap the headset out of a freestyle bmx, simply by RIDING it!

    a honda ct110 would possibly be a close fit but id rather use the forks you mention....mmmm, hydraulic dampening :)
  18. butterbean

    butterbean Well-Known Member

    You cannot beat hydraulic suspension. I would put my forks against the best downhill (excluding hydraulic or pneumatic) bicycle forks out there. I'd also put them against any monarch or springer type forks. What I like best about hydraulic forks is that they're tuneable by the amount and weight of oil you use. I use 10w30 motor oil, and I change it every year. But you're right, bicycle headest bearings probably wouldn't take the load at 60mph. I think it's crazy the kind of speeds people want to go on motorized bicycles without even considering the kind of abuse the bike is going to take at that speed. Unless you're a skilled fabricator, you really should not be thinking about going that fast on a bicycle at all.
  19. HeadSmess

    HeadSmess Well-Known Member

    several years ago i thought of using magnets for dampening.

    basically, its lenz's law... so perfectly suited to the application.

    i should have stopped thinking and started doing. of course, the few people i contacted showed absolutely no interest due to my education level... sticking a magnet down a copper pipe doesnt seem that exciting. too basic. hmmph. mustnt work. wheres the cnc and the shiny anodised bits? a dirty bit of heavy wall pipe and some neos...pffft. go away, while we refer the idea to our R&D department, behind your back... and chuck them a few million to throw around for good measure.

    looks like its now commercially available... or is going to be.

    dangnammit, another million dollar idea down the drain.

    if only i went to uni and had access to large grants to pursue these ideas... or patent them. ever applied for a patent? everyones out to screw you... the office wants at least 10K, the agent you have to go through wants his cut, meanwhile, all you want is to sell this product to someone that will pay you properly(mmm, royalty checks!)... they see it, know its unpatented, has no protection at all, and bang... check out some of these sites that "assist" inventors... "only 1% of our clients realize a profit from their invention" seems to be a common quote.

    when you come across patents on things that simply wouldnt work...you really wonder who screwed who...

    whats smart is to not invent things...but find people that do, and grab all their money before they do!
    Last edited by a moderator: Dec 15, 2015
  20. butterbean

    butterbean Well-Known Member

    Magnetic suspension is interesting. However, there is only one issue I see. It seems that it may not be quite as adjustable as hydraulic suspension. What I mean is, in order to make it stiffer or softer, you would have to change the strength of the magnets. Doesn't seem to be an easy way to do that. With hydraulic suspension, you only need to use more or less oil. It's a bit of a challenge removing oil if you put a bit too much in, but it can be done, just a matter of getting the forks off the bike. Although, I am gonna try to adapt some type of vacuum pump next time I want to change the oil in mine.