Motorized Bicycle – Part 2

My original post on the subject “Motorized Bicycle” has received so many comments that I created this second post, just so people don’t have to scroll down so terribly far to read all of the terrific comments.

I have closed comments on the original post. Please leave a comment here to continue the thread.

Yours in bikes,



  1. jimbeaux says:

    hi lee ‘retired tinkerer’. i’d certainly like to have the info you have on mounting a ‘vertical’ shaft motor on a bike. this is good news for me. thanks. jim abcjimk@bigr[nospam]

  2. retired tinkerer says:

    Hi Lee, hi jimbeaux, the concept of this is pretty simple really. you are simply sort of pinchin the bike tire between an idler wheel on the left side of the tire and the engine shaft on the right. I used a skateboard wheel on the left to ride against the tire,and another one bolted to the motor shaft.a simple lever system slides the motor on the mount left and right to engage-disengage the drive wheel. the biggest drawback that we have with this bike is you have to pedal up to about 3-4mph before you engage the drive, tire wear is minimal, this is the second summer and he is still on the org tire. i think that the drive and idler wheels working on the sidewall of the tire instead of the tread has a lot to do with tire longevity because the sidewall of a tire is made from a much tougher compound than the tread. jimbeaux, if it helps the mount was made from an old bedframe. 10”widex16”long two pieces of5” strap iron were bent 4”x1” with holes drilled to mount to frame and seatpost bolt. center the main frame 4” frm the left over the center of the tire. the rear part of the mount is two pieces of pipe going dowm to the rear axle, i used the handle off the mower, yea i know, cheap but efective. the motor was mounted to a square of 1/2” plywood with the center cut out the shape of the bottom of the motor. be sure your idler wheel and drive wheel are centered on the bike wheel axle. hoe this gets you started.

  3. Arati says:

    retired tinkerer,

    Thanks for the idea of using a skateboard wheel on the PTO. Mine has a horizontal pto with hardwood drive wheels. I can’t wait to try the skateboard wheel. I hope the shaft sizes are the same.


  4. retired tinkerer says:

    hey j-bo, tried to send you a couple pics of bike but your e-mail add don’t work ret-tink

  5. jimbeaux says:

    memjim@gm[nospam] thanks tink.

  6. Rob says:

    hello. would love more detail and/or pics of “retired tinkerer’s” vertical shaft bike motor mount setup. sounds like what im trying to accomplish, only mine is a 6h/p briggs&stratton vertical shaft. thx.

  7. jimbeaux says:

    hey rettinker, please try sending pics to ‘’. thanks again. jim

  8. Rob says:

    retinkerer-please send more info/pics to im trying to do a six horse vertical shaft version.

  9. K says:

    Hi All,

    I been out of the loop for awhile but it’s great to read new ideas.

    I like the vertical shaft with pinch roller idea.

    When I used a vertical shaft engine, I ended up taking it apart and adding a dipper to the big end of the connecting rod and then tapping the case so I could bolt a plate to the bottom making it a horizontal shaft engine. I also had to change the carburetor. The pinch roller idea is so much easier.

    Keep up with the good ideas.

  10. retired tinkerer says:

    ok guys I sent both of you pics of the bike, I tried to find a way to put them on lee’s blog, but couldn’t get it done. lets just say i’m a hell of a lot better with a welder and a torch than i am with a computer! if I can be any futher help, let me know. good luck with your builds!! retired tinkerer

  11. Jake says:

    Forget petrol! Go electric. I made a trike based on this, and it runs circles around gassers…

    – the one I made is like the cuiser trike.


  12. Brian says:

    hey all, have been browsing this page for a while and got some great ideas… but i still have one question….how do you use a brake cable for the throttle instead of the little clip that is standard on weed eaters????

    please if oyou have any ideas let me know
    u can post it on here or email me at
    and in the subject just put bike ideas or something like that

    thanx and any help is appreciated!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  13. Lee says:

    This is from my friend Steve:

    Somedays you just need something to do…

    A friend of mine is real into converting bicycles to gasoline power using various weed whacker engines and chain saw engines as well. There actually a lot of fun to ride and some of his can hit speeds up to 35 MPH. Pretty fast on a bicycle in traffic.

    I rode on of his better ones around that has a 70 cc two stroke engine and thought it was fun. I told him “Hey I should build one of these”.

    About that time another fellow gave me a a broken 12 speed mountain bike. So I fixed it. I peddeled it around for a couple of days and then wanted just a little more motor-vation. I didn’t have a small gasoline engine that I wanted to donate to the cause, but of course there was a lot of HW/SHW robot parts just rusting in the storage shed. Hmm “I think I’ll try electric power just for fun”.

    Such is the humble beginnings of the Electric Launch Electric bike project. A rusty bit of work in progress (as usual)…

    Of course it ain’t always easy being Green

    It can get a bit messy.. He He.. I’m working on that part…, honest…;)

  14. declan says:

    hey retired tinker….
    ive jst stmbled across this page whilst trying 2 find solutions on how 2 attach a verticle shaft motor 2 a bike as opposed 2 a horizontal shaft motor…as ive alread quiet alot of decent lawnmower enginges lying around…however it wuld b appreciated if you could send me a few pictures of the engine mounting and the mechanism which “drives” your drive wheel..
    email is
    thanx any further help and/or pictures will be much appreciated :D

  15. retired tinkerer says:

    hi everyone just finished 2nd bike and will be posting pics on . a couple pics of the first bike are on there now hope they help with your builds rettink

  16. Jay says:

    dont see the pics I have an old 50’s style two stroke lawnboy verticle shaft motor and im playing with idea on hwo to make it work on a bike would love to see pics of yours i didnt see any on your site?

  17. Rene says:

    I got a question about bicycles with engines….
    At what point, depending on engine size,power, and speeds does a motorized bicycle cease to be a motorized bicycle and then become a motorcycle?
    Using a basic 26″ bicycle frame as the platform, when will it become a motorcycle, and have to meet all motorcycle safety standards? i.e.; turn indicators, lights, etc…

    One other thing gentlemen,
    Forget what state and city ordances say about the subject…In your opinions, when does a cross over, gas engine powered bicycle, become a motorcycle?

    I think it should be that anything under 8 hp. is still a motorized bicycle….especially if it still has bicycle tires and wheels, bicycle brakes, and does not use full suspension. (like a motorcycle does)

    I am tired of trying to build something that falls within the “legal” parameters of a Motorized Bicycle.

    I want a bike that’ll hit 55 or 60 mph easy. [ yes I know bike brakes aren’t up to the job, but, just in case I wanted to go that fast, I could…]

    I’d like to see motorized bicycles be reconized as viable vehicles to be raced, and have trophies and money involved. ( would have be backed commerically of course, via advertising…but not allow factory built up jobs that cost 100 grand plus, with teams of professional riders! Wouldn’t take long for HONDA to grab control if allowed….just like NASCAR is a joke today. Those cars are not from stock show room cars, that’re stripped and raced like in the old days by local boys from the farms.)
    Motorized bicycle racing would have be kept in the private sector, and no bike could cost more than a $ 1000. to build.

    All throughout anykind of racing history, it didn’t take long for factory teams to ruin it for the little guy, and push him out of the fun.
    The wealthy seem to think that they can control everything, if you let them…

  18. vhundley says:

    hey guys, jay i just checked web site, and bikes are there. i also have an old 2 stroke lawn boy 5 hp. the way i build the bikes would work for it but remember the speed that you can get out of one of these is pretty well goverened by the rpms the motor will turn, tire[wheel] size and diameter of the drive roller. most small 4 stroke motors of this type turn about 3500 rpms give or take a little. a 2 stroke like those old lawn boys, about 5500, so the damn thing would fly.if i build a bike with the 2 stroke i will put a scrubber brake on it for sure. by the way, both of the bikes i’ve built go about 25 mph which in my opinion is fast enough for bike brakes !!! rene, i agree with you on a lot of what you say, the government sticks their nose in way to damn far here in our little town in ohio no one has had a problem with the bikes i’ve built, in fact most people think it’s a good idea. with gas at 3.00 plus a gal i know my son and my friend ride them whenever the weather permits. you can save a lot of bucks at 75mpg plus.

  19. Rene says:

    There was a fella near where I now live, that was building and selling motorized 24″ bicycles. Most of them looked well thought out and built right. Some even looked close to, (but not quite the real deal) like Whizzers…
    His asking prices varied by engines used and accessories added, yet generally they hovered around $700.00. I remember one was over 9 hundred bucks, and took a long time to sell…I do not know if he was an eBay seller or not.
    I think in about 5 years he must have built and sold at least 2 dozen of them…Yet, to this day, I have yet to see a single one on the roads. Hummm!
    Three months ago, he moved some where else…
    I’ll bet the Cops nailed who ever it was that bought these things, and stopped them…

    Here in my state, and locality, the Cops are very anal…which is Michigan.
    I have a V-12 powered Jaguar XJ-S coupe that has been altered and has no emission controls on it.{ I am not the one who altered it; I bought it this way } It flies….and is rather noisey above 75 mph ( which is when all 12 cylinders sing in a beautiful harmony)
    Too many times I have seen a State Cop coming on strong with his Gum Ball on the roof flashing in a fury…and I have to kick her into neutral and coast along at idle while losing speed…
    So far I have been lucky enough to avoid a ticket..even though I have been pulled over twice…
    Most Cops are not familar with this type of car, so it is easy to B.S. them that it is stock! I stopped driving it 4 1/2 years ago,
    because gasoline costs were getting out of hand. Last time I filled it up it cost me $75.00.. for High Octane gas
    Today, it would set me back between $140 to $160.00 to fill it up.
    It cannot be run on low octane gas. It gets around 15 mpg on a good day on the highway @ 65 mph…IT IS DINOSAUR that I choose to keep for now…in storage. Yes; I know, this vehicle is so not P.C. it stinks…
    But I have digressed…sorry.

    By the way, the dude who claims he put an 18 hp engine into a bicycle, crashed and broke bones, I think is telling yarns…The spelling he uses cries out “MORON”…
    A 18 hp engine is huge, heavy, and off balance if not mounted onto a strong, flat, platform deck. [ like a rider mower ]
    The engine would have to be so offset to one side to align the crankshaft w/ clutch or the like with the rear wheel, that it would be heavy to one side and very difficult to keep balanced upright.
    It would rip out and break spokes like they were toothpicks….

    I am building a 8 hp engine powered bike right now, and the problems encountered to keep this thing balanced and looking right are a nightmare. Safety and doing it right are my biggest concerns.
    Unfortunately; my bike is now a Motorcycle..although it started out as a motorized bicycle concept. ( using a 1941 Hawthorne 26″ bike, but was scraped as unfit for my ideas )
    As I have progressed in the designing and build, it has become progressively neccessary to upgrade everything to handle just a 8 hp. engine. For instance; the wheels and tires are 3.0 x 26″ clincher types that are actually for motorcycles. The hubs are motorcycle as well with drum brakes. Cost to have front and rear wheel wheels and tires assembled with special drums and extra heavy duty spokes…$1,100. OUCH! The bare unpunched rims alone were $200. each.
    My front fork is a specially rebuilt and highly altered Schwinn Phantom springer…cost for this was $500.00.{ needed many CNC fabricated parts}
    The frame cost me $450.00 to have CNC machined parts, and custom bent Chrome Molybdenum 3/4″ & 1” tubing and welded.
    The gastank is not fully made yet, but, the estimates I have to assemble all the sheet metal ( brass )and other pieces is running around another $400.00…
    The handle bar alone was $400.00 ( the bending of handle bar, plus grips, throttle assy., cables, levers, controls, mirrors, stem assy.)
    The Seat will be $350.. a Troxel unit
    The Fenders will be $300.00
    The Headlight,which is a custom designed affair and which I am seeking a patent on, so far is closing in on $500.00…[ the lense alone is from Germany and was $225. it’s ground and polished crystal ..the inner reflector is Platinum plated too. ]
    I have not included the costs of chrome work, nor the cost of the engine build up.

    AS you can tell, this is no back yard junk-scrap re-assembly.
    I lost control, because I am too damn picky, and do not like what crap is out there and offered to build a motorized bicycle.
    Especially if you want safety…and reliability.
    Since I have spent too much money on this thing already,( much to the spouses anger ) I am going for broke and want to enter it in
    custom bike shows later….I’ll keep you posted on my progress.

    PS. if the aforementioned doofus did indeed assemble an 18hp powered bicycle…and actually ride it, he is insane! Talk about power overkill!!!

  20. Brian says:

    hey retired tinkerer, can u send me ur pics of ur bike plz i need to c a few more bikes b4 ill know exactly how im gonna build my own if u can its greatly appreciated

    send it to if u can its really appreciated just type pics or bike ideas oe whatver u want in the subject

    thanx alot milky

  21. brian, check to see pics of the bikes, the next one i do i will take pics of each part as i build it. i’ve been thinking about doing one with most of the mount components made fron wood, and metal components made from partsthat can be bought from the hardware. that would eliminate welding, heating and bending ect. my object for doing these at all was to show my son and some friends what could be done with the minimum outlay of cash, and how to keep things simple. both bikes and motors were either given to me or i rescued them from the trash. i have less than 20.00 in both bikes.

  22. 14Reality says:

    I just saw a 40cc Tanaka PureFire 2-Stroke vid. Most impressive. $630 for a motor, and $200 bucks for a bike with a disc brake…. Sold !! There are so many 35mph roads where I live… Northwest. I will be able to keep up. I was going to get a Crystalyte 503 or 502 with 72 v 35ah, good up to 43-47mph for 60miles. Lithium Polymer batteries are sure spendy though. Whole project would have been about $2200. I could buy and make 3 Tanaka bikes for that much. I was trying to do the green thing. I will have to wait til the LiFePO4 batteries get cheaper. Anyone thought of making gas & electric bikes??? Hybrid style?? GoldenEagle setup in the the rear, and a hub motor/wheel in the front…. or vice versa. The vids for the 40cc….
    & Any thoughts would be great !!

  23. Brian says:

    hey ret tink tahnx alot that should really help me out…but i got one more question for u (if u know how) how would i swtich from the standard bike cable and use that on the weedeater for the throttle instead of the little clip that is standard oin mine…if u can help its grwatly appreciated… thats where im stuck at

  24. jimbeaux says:


  25. Rene says:

    Hey Jim,
    Are those Honda engines?
    I like the good old reliable flat head engines myself. It’s getting harder to find good used ones that are 8 hp. to 12 hp. these days.
    The low hp.,long stroke,low rev. but higher torque engines are rare. Most are the short stroke,high rev.,higher hp., units.

    Anyone got an old timer that needs to be rebuilt? Old cement mixers had good engines. Anyone got one?

    I like the “Ka-Chug and Pop” of the old one lungers. Music to my ears!

  26. brian, if you will check the picture on my myspace sight you will see in the pic that shows the lever system the prbable answer to your problem for your throttle control. in the upper right where the small spring is attatched,to the right of it you will see a small piece with a blue piece on it , that is an electrical connector that i have clamped to an unused 10 speed shift cable. i drilled out the hole where the little z shaped piece fit from the original throttle cable and used a small shoulder bolt to hook it up. that should solve your problem. if i can help any further, let me know rettink

  27. Brian says:

    ok rettink thanx a lot ive had the idea to do this forever but i was always lost on that part thats helpd me in my thinkin tenfold thanx alot ill keep in touch


  28. tom says:

    Kits for motorizing bicycles have come a long way in the last few years. Your best bet unless you like spending a lot of money and throwing a lot of that money away and are very proficient with tools, it’s better and cheaper to get the $329.00 4-stroke 49cc kit from Avoid any kit that has a roller that rolls against the tire. They are only good in dry weather and they do wear tires out quickly but are ok when everything’s working right. Also avoid kits that you attach the sprocket with clips to the rear wheel spokes. Spokes can’t handle a lot of torque and will eventually loosen and you’ll throw a chain. Now, the kits have a sprocket that attaches to the rear hub. That’s the way to go. This kit will do about 30 mph unless you’re really really heavy. 30 mph on a bicycle is pretty fast. If you get a kit with less than 50cc engine, you are street legal in many states.

  29. tom says:

    You people who are talking about 6.5, 8 and 12 hp engines for motorizing bicycles are getting a little off base. 2 hp or less will run a bike about as fast as you want, but if you want a dragster bike, go for it. If you want a bike to ride to work and save gas, you’ll have to try to stay legal and just about any small engine will power a bike sufficiently. Like I said in my other post, save yourself a lot of time and money and just buy a good kit. The site I gave has a lot of choices and the latest innovations in powering a bike. No, I don’t work for them and really, I think they are jerks. I’ve sent 2 emails to them asking questions and they didn’t bother to answer either. My question was if one of the newer mini Honda 4-stroke engines would fit their kit’s engine mount. Their kit comes with a Chinese clone of the Honda engine, but the Chinese engines are still pretty good. It turns out that you can buy their kit with or without the engine and yes, the Honda engine will fit their kit. There are a lot of other online sellers of bike kits and some others may have similar kits, but I think this site probably has the best prices.
    And as far as the revopower powerwheel, the price is not $400. The last time I was on their site, they said it would be about $600. If they ever decide to finally start selling it, no telling how much it will be. It’s not a new idea but it does look like an improvement over all past efforts. But they are sure dragging their feet.

  30. catfish says:

    thier is some great information here. motorized bicycles are becoming very popular. another forum i check out alot is some sharp people thier with good pictures to help with rebuilding the carburator and rebuilding you engines.

  31. skidroadie says:

    Lots of good reading here! I am 44 years old and just got around to putting an engine on my old mountain bike. The 30cc 2stroke leaf blower engine sits on a bracket attached to a T hinge. A spring pulls the engine drive wheel down onto the back tire. I read a lot of info about how a friction drive eat up tires. So, I set out to find a better way to make a friction drive and so far, IT WORKS and does not eat up the tire.

    I went to a farm supply store and bought a few feet of 4 inch wide hay baler belt. It is 1/4 in ch thick and is made of reinforced canvas rubber (tough stuff, made like a tire). I figured if my drive wheel was made out of something like a tire it would last longer, right?

    Anyway, I used a hole saw and cut five 1.5 inch diameter discs and put them sandwiched together on the engine shaft. A couple of 1.25 inch washers keep them pinched together with the castle nut on the shaft.

    So far, I have put almost 100 miles on the bike and the rear tire shows no signs of wear. Mark my words, this works! you can email me at if you want to see pics.

  32. skidroadie says:

    Hi, I just wanted to give you an update…….I have made a clutch system for my friction drive engine. I used a brake lever and cable from a motorcycle and connected the cable to the engine mount (which is on a hinge so it moves up and down). I had to add a rod that comes up from the bike frame near the back wheel hub so the cable would have something to work against. It works really well! I do have pictures of this set up, feel free to email me or maybe the webmaster will allow me to put them on here.

    I did get some comments questioning my previous post about the rear tire not showing signs of wear from the friction drive. What I should have said was there IS wear but not any more than I would consider normal on a bike tire with nearly 100 miles on it!

  33. usochamp says:

    hey retired tinkerer, and anyone else. it would be cool to send me some pics and a tutorial or instructions on how to attach a weedwacker motor to a bicycle. thanks a lot

  34. Dave says:

    I got one of the engine kits off ebay and wow!!! That 50cc engine can drag my old fat arse around 20-25 MPH!!! I get a little exercise when I go up hill, as the engine will need assistance pulling all my weight. A heck of a lot of fun!!! only I don’t ride at night (too noisy and poor visibility). I don’t ride the roads outside of my development because of speeding drivers and steep hills. They don’t even have sidewalks in my area. I’d like to find a place to ride and not make a nuisance of myself or give the cops PMS/heartburn – seems like some of those piss ants are itch’n to raise hell with someone. I know there are good cops too, it’s just the bad apples that annoy people.

  35. William says:

    I believe this may help clear up any legal questions. You can see why Zach little endeavor would get him into trouble.

    Here are the federal DOT rules for exemption.

    The engine system may not exceed 30 MPH on the flat, no wind.
    The engine system may not exceed 2 BHP.
    The engine system may not exceed 50 cc.
    The engine system may not interfere with normal pedaling.
    The engine system must not require shifting.
    The engine system must be a fully independent power source.

    Here is where I acquired this info

  36. HookDown says:

    I installed the Golden Eagle Suburu EH035 4-stroke engine on my 98 K2 Proflex Beast full suspension MTB. This combination works well as a pedal assist in the rugged off-road terrain of the Eastern Sierra around Mammoth Lakes, Calif. The plush suspension of the K2 beast allows me to take the big hits and not crash. The 11 tooth clutch gear (trail gear) with the standard 143 toothed drive ring gives a drive ratio of 13:1. This gives a max speed of about 22 MPH and a clutch disengage speed of about 3 MPH. I find that 15 MPH is as fast as I want to go off-road. I must start pedal assist at around 8 MPH using the middle chain ring and one of the three largest cogset gears. As the speed decreases towards 3 MPH I must shift down to the small chain ring and the large cogset gear and pedal furiously. This last about 5 minutes before the slipping clutch overheats and starts disengaging. By that time my heart rate has redlined anyway so I simply dismount and walk alongside the machine. For my off-road riding purposes the gearing is really not low enough to handle the steep terrain around here, but then, I ride a mountain bike in order to get exercise, so it’s a trade off. So for me, the Suburu on my K2 is the perfect set-up. The installation of the kit was fairly straightforward, but there were a lot of “lessons learned” in the process. Perhaps the greatest lesson is that every nut and bolt must be locktighted (with blue stuff) and torqued down. I purchased the Golden Eagle heavy duty 36 spoked rear wheel and secured all 36 spokes to the drive ring. So far the drive ring is tight and no broken spokes. Julia at Golden Eagle Motorized bicycles has been most helpful and informative. Should you decide to go the GEBE Suburu route, keep in touch with her and save yourself a lot of mistakes.

  37. augidog says:

    this has been an interesting read.

    hello, all. i’m the former admin of, and have now moved on to promoting professional motorized bicycle racing. den of golden eagle is heavily involved, and both of us will be running tanaka setups at the bonneville salt flats in september.

    one of the things i’ve learned about motorvatin’ a bicycle is making sure the chassis is up to the task…i’ve built my laker on some really nice gebe/velocity wheels laced to proven reliable brakes…sturmey-archer drum in the front, shimano coaster in the rear…a combination that just can’t be beat, imo. i’m about to put this to the test at my top-end goal of 45mph with a basically stock tanaka 32cc on a surely-stock golden eagle drivetrain.

    i’m now active as the official gebe-liason at & available to help in any way i can. lately, tho, i’m actually more busy building, tuning, & testing my racing bike than anything else…ahhh, the real world sure can be fun ;)

    more about racing on our new site/forum, stop in once in a while to see what’s up:

    thanks for the cool discussion, lee.


  38. eric papas says:

    Sounds interesting using a blower engine,can you send me details and photos,


  39. Tom says:


    Take a look at our Motorized Bicycle Forum – I bet you will find a ton of info there that will help you with your motorized bicycle.

  40. anubis says:

    I first wanted to build mine with an electric motor after my bike starrted falling apart, then after looking into it i decided gas was the way to go (obviously not cleaner, but at least i can haul ass- i’m a 210 lb rider- and for longer than with electric). Anyways, so I found an old-as-hell (1962 from what i could find out) McCulloch I-43 chainsaw that had a rusted chain. My buddy that co-owns the ranch i found it on said it probably didn’t work, but i could have it. I have no idea on the displacement or horsepower, and i know i could measure it, but it would be a pain in the butt, so i will assume that it is around 45cc. Eventually, after cleaning it up alot- had dried-up grease and grime all over it- and disassembling/cleanin the carburetor, i got it working and successfully mounted it and an external gas tank to my 26″ mountain bike.

    Anyways, i have had alot of problems. First the gear ratio was not worth a darn at about 1:4 and i burned out the clutch, then the starter rope broke, and while i tried to replace it, the spring that retracts the rope after pulling the starter broke. In the meantime, i have improved the gear ratio to about 1:8.17- which should be fine. The only issue is now i can’t start the engine.

    The best solution that i can think of right now is to McGyver a manual clutch like the Wizard bike kit that’s worth around $250- way more than what i want to spend.

    Any thoughts?

    (by the way the shaft bore is 5/8″ and i have a left-handed thread at the end where the centrifugal clutch hub screws directly on to)

    Lee, can you get Zach in on this because i read that he had a similar shaft on his weedeater engine.

  41. Ben5403 says:

    I Have a Question for the zack guy i was wondering how he bolted the wheels to the frame i mean how big was the shaft he used to bolt it on Lee if you could email me some suggestions or even zachs email that would be very helpful

  42. tom says:

    To me, the one thing that is left as far as perfecting bike engine kits is the use of the old SPOKE wheel. If Gebe and some of the other dealers would come up with an ALLOY wheel of some type with the belt sheave or a sprocket attached to, the worry of spoke stress would be over. An alloy wheel could be just as light weight as a spoke wheel, maybe lighter. Why are you guys still depending on the spoke wheel? Imagine the highly dependable Robin Subaru engine with a chain drive with a one gallon gas tank (or at least a half gallon) mounted to a nice alloy wheel. Dependability.

  43. tom says:

    Take a look at this homemade bike from Youtube. It’s a very cool, smart setup, different than all the others. It appears that he’s using a standard gokart/mini bike clutch and chain and somehow attached a kart/minibike sprocket to the crank. And I’m assuming he still has use of the bike’s gears! And it’s very fast, too. He’s using a Honda clone engine and the only thing I’d change is to use a Robin Subaru engine instead, that is if I didn’t already have a Briggs or some other engine already. Not the tiny Robin Subarus, but the larger ones that look much like the engine he’s using. Anyone have an good ideas on how to attach and center the sprocket to the crank? I’d suggest doing this before making the motor mounts so the engine can be properly lined up with the sprocket.

  44. Rene says:

    Sold off the Jaguar, to some clown who is willing to buy premium fuel for it, at 180 Bucks a pop to fill it…used the money to buy something more useful….
    Abandoned for now the motorized bicycle/motorcycle I was developing.
    right now, there is no market for it.
    We are facing severe living hardships and an economic crash to make the depression of the 30’s look like a vacation.
    I am no longer wasting my money on toys and tinkering around. I am preparing a “Survival Homestead” or Crashstead if you will.
    You’d all be well advised to check out this web site, and read everything this man, and his blog members have written.
    Forget about motorized bicycles….

    go to the blog everything from 2004-5 on…
    get ready to crap your pants!

  45. Arati says:

    GEBE my friends. I’m doing 40+ mph and the bike handles like a motorcycle.

  46. Hay Bailer says:

    With fuel being as expensive as it is right now I believe we will see more innovations in this vein. Something like this is not only functional and money saving, but fun to ride!

  47. smith says:

    Guys, the friction drive setup just isn’t the best way to go. It’s the cheapest and easiest (if you’re buying a manufactured kit), but very limited. It’s only good on dry pavement. Forget wet streets, gravel or dirt. And trying to use a vertical shaft engine, it’s going to be an uphill battle all the way. Just look at Youtube for motorized bikes and you’ll see many many great ways to motorize your bike. The absolute best way to come along is attaching a kart sprocket to the left side crank and running a chain to it. Then, you can use all the bike’s gears for hills and flats. And now there’s a kit that uses an electric motor mounted under your crank, and it also utilizes the bike’s existing gears. This has been done for years on homemade bikes but is a brand new concept in manufactured kits. And to the ones who like to go 40mph on a bicycle, you’re nuts. 20 mph on a bicycle is pretty fast. Bicycles’ hardware and brakes just aren’t designed for those high speeds. Plus, you’re begging for a ticket from police if you get caught. Believe me, 20 mph on a bicycle without pedaling is getting along pretty good.

  48. Arati Ecospeeder says:

    Nuts? To a degree. It’s true 40mph on a bike is not for everyone. I always say that when some one asks about my bike which is often. As for the bike, it’s been modified to handle the extra stress along with the full suspension and disk brakes it came with.

  49. Arati Ecospeeder says:

    (hit ‘Submit’ to quick)

    I agree with you about the friction drive . Been there, wrenched on and rode that. But you left out the part about the tire eating. A friction drive can easily eat a bakers dozen of tires before a dialed in a belt-drive bike system breaks a belt.

    I have a question about your chain drive idea:

    “The absolute best way to come along is attaching a kart sprocket to the left side crank and running a chain to it.”

    Correct me if I being dense and missing something. If one connected the PTO of the motor to the crank of the bike; wouldn’t the pedals of the bike be rotating with the power of the motor?

    I have a question

  50. smith says:

    I didn’t mention tire wear because it had already been pointed out and I’ve discussed this on so many forums that I figured it was just taken for granted that everyone knows about the tire wear issue. I think that if you MUST have a friction drive, you’re only using it for fun and the tire wear is the price you pay and you don’t mind changing tires every 1000 miles or less.
    No, you’re not dense. Any good tinkerer thinks of what you asked about right off. Yes, the pedals DO still spin. That’s when you just cut them off at the crank and you have a full motorbike. The solution to this is use a FREEWHEEL crank. Then the pedals can still be used and don’t spin when power is on. Problem is, freewheel cranks are expensive and kind of hard to find. The new electric drive now available that still utilizes the bike’s gears actually does use a freewheel. $400+ for the kit and doesn’t include batteries.
    For a good example of a homemade chain drive setup that uses the bike’s gears, check out this video:

  51. smith says:

    And here is an amazing example of how the bike’s gears change smoothly while power is applied on the crank’s left side. It’s a chopper bicycle, which I don’t care for, but is an ingenious setup:

  52. memjim says:

    i just obtained a mint condition Schwinn Stingray OCC 24″ bike. please advise on the best gas engine for me to install on this baby. thanks. jim

  53. Arati Ecospeeder says:

    Yes, the pedals DO still spin.

    That a dangerous design for a motorized bike. A lower leg crippler. I like the idea of using the bike gears with the PTO of the engine though.

    Connecting the PTO to an extra gear on the crank and running (and losing) power thru the no-pedals crank and the the chain to the derailer is a bit of Gilligan engineering. I saw the youtube vid of the Stingray in slow mo. The chain from the crank to the derailer slapping & flapping considerably. And that was standing still. Connecting and making work the engine PTO more directly to the rear sprocket and derailer would be quite brilliant.

    Similarly, the latest ( actually been around for a while) in electric bike technology is the hub motor. It eliminates PTO to wheel drive train hardware, weight, maintainence and power loss.

  54. smith says:

    Yes, the chain flaps and slaps some, but it’s to be expected for such a long run of chain. The bike’s a chopper and the chain may be somewhat longer than a normal bike. On this particular bike, I don’t see how the leg would be injured. I could see it on the more “Gilligan” approach, but if someone could go to the trouble to engineer this rig, I’m sure they could fabricate a guard for the sprocket and chain. Yes, hub motors are great. Some have so much torque (the Crystalyte) that they will bend your forks. But I’m discussing gasoline engines, an entirely different matter. E-bikes do have their place, but are still severely limited by battery storage. I do have an Ezip Trailz and drive it daily but range is very limited.

  55. Arati Ecospeeder says:

    A shorter more direct chain route from the PTO to the rear deraileur would might that Stingray workable. Why involve the crank hardware and long chain run.

    Fork bending torque eh?? That’s encouraging. For me I won’t have a motorized bike without full suspension so that is not a shoot down factor in my book. I want to do an electric MTB for my next build so I can go on off road park trails. The torque and lack of engine noise make it perfect. And the idea of front wheel drive is appealing.

    I agree that battery technology is bottlenecking E-bike advancement. The is a 1000 Watt hub drive unit advertised on Lee’s site here that breaks the 30+mph e-bike speed barrier. It’s got a really great design engineering wise. The batteries are in one the the hub drums. But the set-up is way expensive and I question the longevity of proprietary $700 batteries that are subjected to so much centrifugal force and wheel shock.

  56. charliejones says:


  57. Lincoln says:

    Those are some pretty nice choices you are deciding between.

    I personally like to weld something up myself, but thats just the way I do things.

    Never made a gas powered one yet, as I don’t think it would be street legal here. I have a couple real fast electric ones I rigged up though.

    It is alot of fun, especially with the electric motor, because it is so quiet and smooth.

  58. Calum says:

    hello, I live in Western Australia and about 10 months ago I found out about motorized bikes (before then I had never heard of them) and about 6 months ago I bought one from for around $250 including postage (just over $200 US) and within a couple of hours of installation I was riding around, it has a 49cc 2 cycle engine and I can go for about 5 to 10 hours without needing a new tank of fuel (it hold almost 2 liters, almost half a gallon) with a top speed of about 40km/h to 50km/h on the flat. the spare parts for it are very affordable, a new set of generator magnets only costs $28 including postage (around $23 US)and gets here within a couple of days. ( I had to buy a new one after cleaning with a high-pressure hose and accidentally filling the generator with water and part of it going rusty)

    zbox have a link to a US seller on their website, if you are looking for a very cheep motor for a bike I would recommend having a look at these guys, over here in aus most of the motor kits are exactly the same, just different prices (some almost $1000 for the exact same motor kit).

  59. GreggB says:

    So, the one question I have, which doesn’t seem discussed much; in the past ~3 years that you’ve been using this setup, how many broken spokes? My rear WTB DualDuty XC 700c wheel was built-up w/ non-butted stainless steel spokes…and I simply want to know – since mine’s largely a touring/distance & on-road commuting bike, does anyone think that’d be good enough?

  60. Mike says:

    Hi, I’m thinking of getting a motorized bike but was wondering if it might not be better to just go ahead and get a moped.? Any reasons why a motorized bike would be better? Thanks.

  61. chris says:

    Hi all I have a staton kit on a giant stiletto frame eho35 engine i am replacing it with the honda gx 50 i am also getting ready to build frames with the same jack shaft set up so you will use the bicycles gears to go

  62. augidog says:

    why a motorized bicycle instead of a scooter or moped?

    you have to be able to make use of a <30mph vehicle, or you’ll be dissapointed. if you’re only involved at the hobby level, then you’ll LOVE whatever you come up with.

    but, if an MB does it for you, the primary beauty is that you choose & configure your chassis/bicycle first….go for a safe seat-height, feet flat at a stop…bars should be chosen for shoulder/neck comfort….etc…keep at it until that ride fits you like your favorite pair of jeans. it’s about the bicycle first for most of us.

    scooters & mopeds, light motorcycles…try finding so many bolt-on mods & upgrades…and try paying for ’em ;)

    when the power/weight/need is appropriate, there’s no more versatile or affordable a 2-wheel vehicle going than an MB.

    visit Tom & the gang at for tons of info.

  63. Pete says:


    I have a moped and an electric bike and I would have to say that I prefer the electric bike. I definitely find the electric bike a better and more enjoyable ride. I like being able to mod my bike which is something I really enjoy. was a very useful and informative site that I found to be very handy.

  64. steve says:

    Your lives are about to change…

    Anything you want to know can be found at

    I myself have just put a gas engine on an electric IZip along with a jackshaft kit from sickbikeparts that brings the chain over to the crankset so that I can keep the electric motor on the right and best of all, I can use the 7 gears on the rear tire with the gas engine. Have a look!

  65. paddy says:

    Steve, when I saw the link, I thought you were going to show us your gas/electric setup but you just showed us the sickbikeparts kit. Already seen that. And be aware that is about as anal a forum as you’ll ever see. Or it used to be. It had a lot of moderators and they all had extremely big heads and loved insulting people.

  66. Brian says:

    i am back every one, i have my engine set up found all of the shroud (actually one half is from my other wee eater but it bolted up perfectly. now in the process of having my bike peg cut so it will fit over the threaded shaft out of the weedeater.(too thick of a peg to use the nut) and i have the original throttle hooked up to a brake lever (temporarily) until i see if it will fire and the throttle works, then i will be refinding my old brake cable. then i just have to find out what to use for a motor mount, and then i just need 2 chains to fit on my bike for the pedals(old one was rusted beyond repair) then i will tie the 2 chains together(not literally) and i will hopefully have me a 1963 Huffy Galaxie motorized bicycle. then comes the paint job!!!! in hopes to have it completed within a month of two!!! wish me luck.

    any questions or advice for helping me in my accomplishment would be appreciated and can be sent to thanks

  67. Brian says:

    had a typo lol the other part of my shroud was off another WEED* eater just figured i would clear that up

  68. Joshua Hardy says:

    Hey man have you checked out They have motor kits for bicycles as well as fully assembled bicycles and parts for motorized bicycles.


  69. Brian says:

    no i havent, judging by your name though it sounds like a self promotion lol but no matter i will definitely check it out, but my only problem i have seizures and my doctor tells me i cant work or drive so i have been checkin on doing this as a mode of transportation, but not having a job i dont have the extra cash to just be spending on fully assembled kits or motors, so i am trying to devise my own on the cheap but if you have an ideas or suggestions, let me know it would be greatly appreaciated… also i will look at the photos of the kits and mounting to se if i can maybe score an idea on how to use it on my bike so thanks for the help

  70. Elf says:

    Brian, your best bet by far is to just purchase an Ezip bike from Wally World or amazon or whoever. Depending on when or where you order or buy, the price ranges from $246 to about $346. Why bother building one from scratch and spending much more than just buying a bike. It’s not possible to build one cheaper than just buying one. It’s a good dependable bike and the lowest priced one ever. I’ve driven mine about a year and a half with zero problems. Except my batteries are nearing the end of their life span, which is normal.

  71. Brian says:

    comment to elf: thanks for the advice and i sincerely mean this in the nicest way possible when i say this… im really just looking for something to rig up and see if it would actually work, without being able to work or drive(orders from my doctor) i have just too much time on my hands sitting at the house. and its really more of an idea and a way to pass the time. and just a way to get to the small stores around here. and really spending that much on a vehicle as it could be classified and riding it around here would not be worth it. things around here get stolen fast so i would feel alot safer just builind something that noone would steal as quickly as something premade prefabbed and looking really nice. but all in all its just a small project to pass the time and have something to do. but when it come to the gasoline powered versus electric, i would rather just have the gas to be able to stop at a gas station and have a head turning bike, and make people wonder why in the world is a guy on a bicycle filling up at the pump lol? …and i meant no offense when i posted this, and i didnt mean to sound rude but if i did i am sorry.

  72. memjim says:

    Brian, as i read your post i visualized this. the kind of ‘mobike’ you’ll produce will not get you to a gas station,will not be stolen and won’t be seen by anyone’s head that can be turned. you state every reason why you can’t/shouldn’t build a ‘mobike’,then you’re at the gas pump turning heads. Brian, i don’t believe this concept will work out for you. please rethink it and repost it. i’m curious about what you’ll come up with next. i’m also on your side amigo. build a ‘mobike’ and hit the road! no fear allowed!.

  73. Brian says:

    well i will look into it and see where the flaws lay and rethink it and see what may work out and thanks for the tips, just looking for tips to see where i may go wrong before i get started is all im doing on here and just trading ideas with people

  74. steve says:

    This may give you ideas. It’s not too often that you see a scubber set up with a Briggs & straton style motor…..A 30 buck build!

  75. Alex says:

    Brian, it sounds like you’re more after a concept and a way to impress strangers than having a practical bike to drive. If things get stolen that easy, you must live in a really scummy location, maybe an inner city ruled by uncivilized savages? Well, unless you have a cutting torch and welder and are really talented, you’ll end up spending more money starting from scratch than it would have cost to just buy a bolt-on gas motor kit or a complete electric bike. Things are very expensive these days. If you want to just impress people, just strap some kind of gas tank on the bike and pedal down to the gas station and fill it up. If one of those easily-impressed people ask where the engine is, tell them it’s hidden inside the frame.

  76. Brian says:

    well i meant no offense to anyone but its not a way to impress complete strangers i am more into the idea of just making people turn heads and to think wtf? its just a simple project i am working on to (again) see if i can accomplish it and then part of it is just to see if it will actually work… i have seen some in motion but i want to see if my setup will work and maybe inspire others to think outside the box too…..i just asked for ideas not smart remarks about what i am trying to accomplish, i do not have a welder but i have a friend who does and i am an experience (not licensed) welder so i could rig it up… and so far all i have in the bike is 10 bucks, so if you can tell me where to get a electric or bolt on kit for less let me know until then (and i mean this is the nicest way possible) dont assume i have hundreds into a bike or anything before you post comments about me spending too much… and this part of the message is to steve thanks that video is very informative… thanks

  77. paddy says:

    That video of Vernon’s homemade setup is pretty cool. Not much detail on that ingenious speed control though. Does anyone know what is good to bolt onto the drive shaft for a roller? Maybe something that’s already 5/8″ ID. It’s good that a vertical shaft engine was used since they are much more readily available and cheaper than horizontal shaft engines. And it sits lower on the frame.

  78. elvis says:

    retired tinkerer, your build is really fine. It’s been going on 2 years now and you’ve still not posted the pics you promised. It’s very difficult to grasp it looking at a quickie video. Would love to see more.

  79. billy says:

    Well, Lee, it looks like the RevoPower bike engine kit is a total bust after all that ballyhoo. Site is gone. Zilch. Maybe they heard the old story that 2 strokes would be banned. Many think the story is perpetrated by bike engine sellers so people will grab them up.

  80. lee says:

    Yeah, it looks like RevoPower won’t happen :-(

  81. lee says:

    I see that while I was away for a week at Burning Man, downunder, jimbeaux, asterisk and glenn started some weird discussion that had nothing to do with motorized bicycles. I have removed those comments. Don’t worry adoring readers, you didn’t miss anything.

  82. Joshua says:

    Will one of those 6.5 horizontals fit on a bicycle

  83. Bill Snow says:

    GOLDEN EAGLE FIX: Broken spoke problem is common with this kit. I have built up several motorized bicycles over the years and the Golden Eagle is one of the best kits out there . Back to the broken spoke problem, this has worked for me: Where the spokes cross, wire them together, then apply JB Weld to where the spokes are wired together. try to find stainless steel wire if you can so it will not rust. If not, I have used regular light weight wire and it worked just fine. For me, that ended my broken spoke problem. Another thing I did to the wheel was to drill a small hole in the drive ring where it snaps onto the spokes. wired the ring to the spoke using the small hole I had drilled and again applied JB Weld to the spoke and drive ring at that wired spot. Don’t know if that will help the broken spoke problem but it will make sure the ring stays secure to the wheel. This maybe overdoing it and unimportant but thought I would pass it on any way.

    Best Regards

    Bill Snow

  84. Tom cat says:

    Hi ya’ll! There seemed to be a kinda contest about who build their bike the cheapest, mine cost $5 to build (secondhand weedeater motor was $5, everything else was scrap parts laying around, lol) The main problem I had about building a motored bicycle was that everyone kept saying “weedeaters are different, so you have to look at yours to see how to mount it” well I’ve found out that they’re actually not THAT different from each other, and I found a way to mount them that will work for ALOT of weedeaters. The one thing everyone has to know is the tiny clutch on weedeaters is not strong enough to pull someone, so the clutch has to be removed, and the nut that holds on the flywheel underneth (the big finned wheel with the 2 magnets) that is the nut that has to be used to hold the peg/spindle on. I recommend getting a small engine shop to loosen the nut, because it’s pretty well torqued down, and some of them require a long deepwell socket. Anyone with questions on building their own bike please let me know, and I’ll be glad to help, I’ll even draw a diagram to show how to mount the motor if someone needs it. Happy New Year, and happy motoring!!! ;D

  85. Brian says:

    i would enjoy to have a diagram drew up for me to see how it would differ from how i am going to set my up the advantages and disadvantages of both ways… thanks to all that can help

  86. roy says:

    i just got 2 grubee gt5 skyhawk 66 cc bicyle motors i have a mtn bike and a beach cruiser i am going to install, can not wait

  87. memjim says:

    Good goin’ Roy. Where did ya’ get the motors and how much are they sellin’ for? thanks and good luck. jim

  88. roy says:

    hello tinkerers, i build motorized bicycles also, i do have a brand new grubee skyhawk 66cc motor kit, still in the box if anyone one would like to buy one email me i am ohio near columbus and marysville,i will take a loss on it considering the shipping it cost me but i will sell it for 120,00 it will make someone a good project and i just dont have time to do it anymore i have 3 bikes for myself to ride and if you are interested email me at hope to hear from you.

  89. roy says:

    jim i bought it thru but they have many other websites with diffrent names same company thoe. i never had any issues with this model. i have 6300 miles on my first bike i ever built and still ride it. i am tinkering around for a 3 wheel bicycle and trying to refab the rearend to modifie the braket for the motor but having some minor issue but i will work it out

  90. Brian says:

    hey everyone i am back still no luck with the motorized bike yet, have had major problems come my way mom had cataract surgery and everything, now we have moved lost some parts for my bike but are there any new ideas out there for this? still only 10 into the bike and just got one weedeater running the other day now if i can just get this one running… got longer wires and thicker gauge for the kill switch off of an old battery charger. still need to get the spindle attached when i find me a new one, and need to get it mounted and then rig up the throttle and i should be in business!

    thanks to all for the help Brian

    if you have any ideas or tips shoot em to me at, just put bike tips or something related thanks….please no spam!!!!

  91. papsmear says:

    The advantages of gas are obvious, but if your trip is 20 miles, you’ll really be stretching it as far as range goes since electric bikes are still in the stone ages. It’s still the batteries that are the problem, but as always, a battery breakthrough is “just around the corner”.

  92. On the contrary, I think electric bikes have really made great strides in the past few years. Since they upgraded to Lithium batteries, charge cycles can last between 20 and 30 miles. Unless you’re taking your electric bike on an extended tour, this is usually enough for most commuters.

    I’m using a BionX electric kit on my Specialized Hard Rock mountain bike. Here are some details about the installation:

    I got it from and they seem to know everything there is to know about electric bikes and electric bike conversions.

  93. Adam T says:

    Great bike i have bought it and tried it out really excelent quality but the design didnt quite speak to me. I changed it at bicycle motor they have chrommed it and now it looks a lot better if you have that bike i really advice to do the same.

  94. vandersloot says:

    Adam T, that’s very strange. You had a hub motor chromed? It sounds like you’re getting an electric bike for the wrong reasons. You’re only into the “fashion”? Do you really think anyone else will even notice the chrome?

  95. Brian says:

    got the peg mounted to the weedeater…now i just need a way to mount it on hook up the brake lever and hopefully will be off… will keep updated on how it goes…. to anyone who knows who zac is and where i can find the pictures of his bike with the dolly wheel and no pedals please let me know, i would like to speak with him about it to swap an idea thanks brian

  96. Brian says:

    back again got the motor mounted and all just need another chain to add to the bike to have enough clearance to make it and need the gas lever and will be ready to ride!

Leave a Comment

Do not write "http://" or "https://" in your comment, it will be blocked. It may take a few days for me to manually approve your first comment.