Anyone tempted to use cheap motorbike engines?

Discussion in 'General Questions' started by 5-7HEAVEN, Aug 11, 2007.

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  1. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Hi. i know that many of the motorbike/pocketbike/moped engines are illegal because of their large displacements, but has anyone considered using these engines on their bikes? one 90cc engine sells new/complete for $79.95 on ebay, others going for about $250 with transmissions. it would seem practical enough to fab a mount into the bike's frame and run jackshaft and sprocket to the rear wheel. would their larger sprocket be compatible with what's available for motorized bicycles, as far as chains and sprockets are concerned? i would LOVE to run a 5-6hp bike engine with 4 speed auto on a fortified/modified bicycle frame and balloon tires.
    your thoughts, please.


  2. I was thinking the same thing lately, search for Lifan engines on ebay, you'll find what I'm talking about, although they are a bit large.
    Link to my thread:

    Those $80 49cc 2 strokes on there for pocketbikes look just the right size, and some come with a CVT.
  3. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:yeah, the LIFAN engine/trans is one i'm seriously looking at. maybe i'd just have to buy the engine, then have the bike frame built around it.
    i'm searching the archives looking for super-strong and wide wheels and tires to use, front and rear.
  4. Yeah I was thinking a custom frame would be the only way to go.

    but then I bought this

    I just can't afford the time or money right now to try to do another bicycle, so I figured this would be the next best thing. I really don't want to get away from bicycles though, I'm torn between, lol.
  5. Yes....Illegal or not...It'd be really neat to have a bike go 55 MPH or so....I'd even pretend to pedal just to freak people out!.....Go for it!....I have thought the same things too....Actually I have an old YZ 250 dirt bike in the back yard less the engine ( I bought everything minus the engine for $100) That I was going to try to install a pedal system onto and then put a 50 CC dax on it....I think pedaling a YZ 250 would freak out a lot of people too!...f course the <50 CC could keep her legal to boot!
  6. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:well, i'm really not interested in doing 55mph. i'd be satisfied with reaching 40mph quickly thru the gears, then easily maintaining that speed.
  7. 55mph :eek: on a pedal bike :eek:, I dont think so.
    I'll be happy to cruise at a consistant 15-20mph with bursts up to 25-30mph max.
    I figure I could pedal at a good 10-15 consistantly so going a bit faster with little to no effort is fine with me when on a bicycle.

    When I want to go faster on two wheels I'll just jump on the cycle and go for a ride.

    I feel an engine assisted bike should be able to start from a dead stop with a 200lbs. rider on it and get up to 30mph within a reasonable distance.

    OK I do have a project going for the wife and it's simply a pocket bike engine with a CVT on her old mountain bike.
    I hope it works and it is just an experiment for me.

    If it works at all I'll be happy, if it works well I may put it on my bike :D
  8. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:okay, another engine has my full attention:

    ZENOAH G62PU engine, 62cc, 5.4hp@9500rpm/3.04lbs TQ@7500rpm, 87octane+, 6.6lbs weight...$349.00.

    davesmotors has many other engines, and 3.5hp units sell for $159. the 62cc engine interests me because its power peaks from 1500-4500rpm LOWER than all of his other high-performance motors.

    compared to the LIFAN engine/trans and BRIGGS&STRATTON/HONDA which weigh 43lbs+, this ZENOAH weighs less than my ROBIN 35CC engine!

    well, it's cheaper than the 5hp HONDA, and in the long run,cheaper than prepping the BIKE to accept the 50lb LIFANS/BRIGGS/TECUMSEHS.
    Last edited by a moderator: Aug 13, 2007
  9. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:after research on this G62PU engine, it is not a good candidate. there is no clutch or flywheel setup, as its primary use is for r/c airplanes. there is a conversion kit, but it is rare, not in production and expensive.

    hmmm, maybe a pocketbike engine.
  10. gone_fishin

    gone_fishin Guest

    bolt-on-able-ity is a huge factor to motoredbiking, the large majority of folks just don't have a welder hangin out in the garage.

    that's not to say the ideas here aren't good ones, i was merely addressing the "why" of the happy-time's success, IMO.
  11. augidog my vision would be for someone or some group to put together a kit using common pocket bike components like crankshaft, piston, cylinder, carb, exhuast, ignition with a custom crankcase that will allow gear reduction and a (preferably) combo-auto/manual type clutch.

    The custom crankcase would have the bicycle frame mounts built in and the needed clutch hardware.

    It would be cool if we could change the gear reduction right at the engine a little bit.

    I'd like to see a kit with better controls which I know are out there.

    Now you ask, WHY why do all that when we have the "happy time" kits my only answer is because the pocket bike engine parts are so readily available.
    Plus if the 2-stroke kits are done and over with because of the 2-stroke ban then we should/could have a decent if not better replacement handy.
  12. gone_fishin

    gone_fishin Guest

    agreed, but i was addressing the need for kits to install an existing and available engine, the honda 50 and clones.

    i'd love to see an integrated-reduction/clutch 4-stroke, too...wouldn't that be a hoot?
  13. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:augi, i'm with "just for kicks" for similar reasons. i believe the OEM 47cc pocketbike engine is a GREAT candidate for motorized bicycles. from pictures i've seen, there are 5 mounting holes threaded under the engine case. a simple plate mount bolted onto the bike's frame tubes stabilizes the engine. from there, we need to experiment with pulleys and sheaves, or CVT, reduction boxes, chains and pulleys.
    since welding is not yet one of my practiced skills, i will try to follow augi's suggestion of bolt-on-ability for the benefit of myself and any interested parties. my primary reason is for more dependability, more parts availability, a quicker bike...and more HORSEPOWER! it's like driving a 500HP Camaro. ya don't have to race it; ya just have to know you have all that power.

    ebay seems to have many pocketbike engines for sale. so begins another project for me.:cool:

  14. I got an experiment going with one of those 47cc pocket bike engines.
    I havnt got all the parts together just yet but it looks promising so far.

    The thing that bothers me the most right now about that engine is the cyclinder, it is a one piece (head & cylinder) with small fins and it looks as if they removed the heat shield around the cyclinder so I will have to make one so max air goes around the cooling fins.

    As I get more into it I may spring for a much higher end pocket bike engine just to see what could be done but thats a long way off still.

    I hope to get a little more done today on it and hopefully I'll get the last needed parts today.
    I hope to get it done before the Dream cruise so the wife and I can just motor downtown(pontiac) and check out some of the old cars cruising this weekend.The cars are cool to look at but they waste so much fuel. :)

    Ultimately we will need to have a 4-stroke that fits better than the current models out there, it will have to be built more like the current "happy time" engine I think.
  15. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:today, i will bid on a pocketbike engine on ebay, probably one with CVT,plus extra clutch drum and socket.

    just for kicks, when i run into snags, i'll be contacting you for support.
  16. OK, I'll help as much as I can.
    My project is a rear rack mount, engine is to wide for frame mount.

    Right now I can tell you that the CVT I have has to go on the right side of the engine which puts the pull-start on the left, the carb in the front and the exhaust port out back.

    So yeah the engine is backwards because of the reversed gear reduction on the CVT forces me to mount it that way or else the bike will be going backward :)

    My concern is if the CVT will work that way or maybe it is set up for a right hand drive pocket bike IDK.

    I have an exhaust pipe for it that will need a little rework but it should be perfect mounted near/on the left rear rack rod.
    The fuel tank is still up in the air as to how and what I'll use.
  17. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:just for kicks, today i bought a 49cc pocketbike engine w/CVT for $99.95+$25 shipping, on ebay. i believe it accepts the same 76mm clutch as my ROBIN 35cc friction drive. if the gods are with me, this engine spins the same direction as ROBIN, and my STATON friction drive box and roller will bolt directly on. if it spins the wrong way, i cut out the box to accept the engine on the opposite side.

    i've hear that this engine produces 4.4hp. if so, i'll use a 24" or 26" bike for the prototype. i already have 2.2hp on my 20" folding bike, and it is awesome. twice that power and it'd be death on wheels, as another member's wife complained to her husband.

    just for kicks, can you share specs with me, like length/width/height/weight/engine crankshaft rotation? does the crank and the CVT sprocket rotate in the same direction?

    thanks a bunch for your support!
  18. Just wondering, did you buy that motor from "T-motor sports".
    The one I pulled up says 49cc W/ cvt but it looks like the simple chain drive that I got with my 47cc.

    I had to buy this CVT seperate from my engine and if you look close you can see the gear reduction behind the CVT and since it is only two gears it reverses the direction forcing me to reverse mount the engine but it should still work as long as the CVT was made to spin this way.(I'm doubtfut but all I can do is try it)

    I have to make a shaft for the sprocket with a bearing on the end to support it just to get the chain back to the left side.This will be the biggest hurdle.

    If I find that this CVT will not work or starts to come apart because of the wrong rotation I'll just put the chain drive gear reduction on and flip the engine around and try that.
    Last edited by a moderator: Aug 16, 2007
  19. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:their seller name was "gold3288gold". their store name IS T-motor sports.

    why? are they bad news?:confused:

    just for kicks, you bought the REAL "CVT" component. mine cost $25 if purchased separately from the engine i bid on. i don't think i'll be using my "CVT" anyway. i'm gonna try to bolt the pocketbike engine directly onto STATON friction drive OR their gear-chain box. if i'm lucky, the motor will slip right in.
  20. I dont think they are bad news but that auction I pulled up is a misrepresentation of the product they are selling IMO.

    Yeah I got a real CVT, the 47cc engine cost $59 and the CVT cost $25-$40.My engine also came stock with the chain reduction unit on it.
    I know I shouldnt bother with the CVT but I just want to see if it can help with the start off and then achieve a decent top speed.

    Well your project sounds very interesting with the use of the staton drive.

    These little engines seem to use the same size drivetrain mounting configuration I just wonder if the clutches are the same.

    I got what I hope is the last needed parts wednesday but probably wont get to work on it much this week.Thursday I have someone coming over to buy/pickup a vehicle I'm selling and saturday I'm going upnorth to pickup a trailer I'm buying so maybe I'll get a bit done friday but we are busy.

    I need to make the critical part, the output shaft extension and adapt the right size sprocket to fit.It has to have a bearing to support the end so I'll have to take my time with it to get it right.