Scooter 3spd Chainsaw Belt Drive




I built a gas powered inverted push scooter using a chainsaw for a motor, two customized pulleys, and v-belt. I later added patios instead of the foot pegs and an aluminum cover for the rear end. It worked great and my son would go about thiry miles an hour, and me being almost three times his weight went about 10-15 mph. I made a few changes to make things work and will try to list all the changes as it has been a couple years past, and I no longer have it.

Step 1: Later Mods Added for Safety and Comfort

I later added patios to stand on because the foot pegs were a bit uncomfortable after awhile. Then I added the fairing from aluminum sheet and painted it red to match the scooter. The fairing helps protect the rider from getting anything like feet, or, shoestrings caught up into the rear wheel assembly.

Step 2: Locate and Dissect a 3-spd 24" Bicycle Hub

This 3-spd hub I got from an old dillapidated 24" J.C. Penney's bicycle. I think I paid five or ten bucks for it. It was all rusty and everything, all I wanted was the 3-spd hub anyway. First I cut off all the spokes off of it. Then I took off the chain sprocket by removing the split clip on the outside of the sprocket. Then I put the sprocket end of the axle into the drill press hanging down. I then turned on the drill press and used a Dremel cut-off tool, and cut off the spoke holes and lip on the bottom end. Leaving the housing flush, and even with no lip at all. This is done so that the modified hub will slide into the modified plastic wheel hub from the rear wheel of the scooter. This is discussed in the next step.

Step 3: Modify the Plastic Scooter Wheel

This is where you will cut out the center of the hub of the wheel where you slide the hub into. Its been so long don't remember exactly how I did this. But, I think I put a narrow milling bit into my drill press and mount the wheel to the drill press table horizontally, and a bit off center, so that you can spin the wheel manually, and cut the inner diameter a little at a time. The diameter depends on how thick the 3-spd hub is. After the inside is cut out of the hub using plastic/ steel epoxy coated on both the plastic wheel and the 3-spd hub, slide the hub into the wheel and wipe off the excess, and then put it back into the drill press base horizontally, and slowly spin it, and tap where needed to balance it, so there isn't any wobble. Let set to dry.
On another note, you can also use one of the rear wheels thats on one of those childs 12" wheels. (little bikes) The custom pulley I make in the next step will work on either. Something happened to the milled wheel and will let you know what, later down in detail. Note the tire is not one of those knobby tires that are usually found on these push scooters. This tire is a low profile treaded tire that holds more air, and does not sway into turns. The knobby tires are taller and will sway and sometimes pop of the rim under heavy loads and higher speeds. The tires I bought can be found at some high end bicycle stores but only cost about $15. They are called Impac tires 12 1/2 x 1.75 .

Step 4: Make Custom Pulleys

In this step you will need two v-belt type pulleys. They can be bought at some hardware store or a TSC (Tractor Supply Store). I don't remember what size they are now, but one has to be larger than the sprocket. The sprocket will fit into the center of the pulley and bolted to it. The other will be larger than the 5 or 7 tooth gear on the chainsaw. First I counted how many teeth the sprocket had, measured the diameter center of each toothe and divided the numer of teeth into 360. On this particular sprocket there were 18 teeth , which figures out 20 deg. apart. I made a computer template from an Easy-cad program, taped it to the flat side of the pulley, and centered it. I first found a large bolt and washers and a nut and put it on the drill press horizontally and lined up the first of the eighteen holes. Drilled first hole, then I rotated it manually to the next hole and so on. The last step was to mill out the larger hole which should fit just slightly wider than the sprocket guts, but not the teeth. If your holes are lined up good the sprocket will fit perfectly. Then I used, I believe, 3/8ths in. nuts and bolts through each hole mounting the sprocket to it. Due to the space restrictions only 9 bolts can be used every other hole.

Step 5: Frame Modifications

The kids scooters normally comes with the frame hanging low, with a plastic platform, which you stand on. The platform must be removed, and the gooseneck disassembled, and the frame flipped over. This will look like an upside down "V". Reconnect the washers, bearings, etc, like they were originally. The rear brake mount will have to be cut off, and a new wider one made, and welded back on, because the 3-spd hub is a bit wider than the original wheel. The frame will also have to be stretched width wise, a bit wider to allow the hub to mount where it was originally. Drill the hole for the brake assembly. The handlebars will have to be raised to almost max height, because you'll be standing on the rear axle and holding the handlebars at a higher position for stability. You don't want to be leaning or put to much pressure on the handlebars, for safety reasons.

Step 6: Motor Mount

First you will need two right angle brackets, a turnbuckle and two eye bolts. They can be found at most hardware stores. The angle brackets I found in the lumber hanger/brackets area. Turn buckles are usually used to stretch, or pull fencing, or door frames tighter. Most commonly screen doors. Also buy a long steel rod or pin 6 to 8 inches long.

The yellow seen in the first pic is the belly of the chainsaw where the gas tank was. DRAIN the fuel tank, and connect and mount an auxiliary weed eater type fuel tank on the handlebars.

Place the brackets edge to edge, where a seam is in the center. Drill 3 or 4 holes in each bracket base and one larger one in the same area for the rod or pin thru each side. Then place over the chainsaw housing and drill thru each hole in the bracket into the chainsaw housing. Screw self tapping machine screws to hold everything together. Slide the rod/pin thru one side of the bracket, and then thru one eye bolt, and then tru the other side bracket. I believe I cut a groove around both ends of the rod or pin, just outside the brackets, and put cir-clips/keepers on there to keep it from sliding out. Screw in the turn buckle to the end of the first eye bolt.

Drill a hole the diameter of the shaft of the second eye bolt thru the frame brace where the platform used to be mounted as seen in the second picture. Slide the eye bolt thru the drilled hole and connect to the other end of the turn buckle. The turn buckle is used to keep the v-belt pulled tight and the motor upward on the frame. Ideally if the rod /pin had rollers on the ends it would make it easier to tighten. (less friction)

In the later mods, I took off the stunt/trick pegs and replaced with patios and made a red aluminum shroud/housing to cover this entire area seen in the third picture. The velcro is glued to the frame brace where the other eye bolt goes thru as seen the the top edge in the third picture. The third picture is what you should be close to seeing when this step is done.

Step 7: 3-spd Axle Set-up

This is where I made a mistake to some degree. I chose a three speed axle from a J.C. Penney bicycle where the chain is pulled out, to change gears by a cable that comes straight out. The problem with this is that you have a cable bowing out from the side about where you feet are and its way to easy to snag on something as you go by, or slip/trip off the pegs or patios and get your foot caught in it and get dragged, etc. So what I did was just select one of the three gears by pulling on the chain and leaving it there. Also I wasn't at that time sure how I was gonna tighten up a peg with a cable going, or coming out of it. What I found out later is that if I used one of those little kids, 12" bicycle wheels, with the sprocket attached, it gave about the same torque, or speed as the second gear did. Dooh! The modified pulley still would fit that sprocket as well. Now on second thought, I may have just used that 12" bicycle wheel sprocket and all, or tried one of those Sears 3-spd bicycle sprockets, where to change gears, you turn a grip on the handle bars and it pulls a cable that runs parallel or flush with the wheel and changes gears with a ratchet type mechanism. This would all be neat, and snug under the patios. One, if they have the money, might try one of those Shimano hubs with 3, or 7 gears, but they are quite expensive. I believe the Penney's one was a Sturmy-Archer.

Step 8: Finishing UP

Now at this point you will need a v-belt. I think I used one around 54" long, I really am not sure, now. Remember you have a little play with the length and the turn buckle. I believe I bought two belts till I got the right length. Connect the belt around the bigger pulley, and the other end around the smaller one at the top, by lowering the whole motor. You may have to disconnect one end from the eye bolts to do this. Then reconnect the eye bolt and tighten. Fuel up and your almost ready to go. Oh, I used some of that fuel additive for weed eaters gas so they don't smoke. Smokeless, AHhh... This is a pull start chainsaw and one other problem I had was getting it started. You see the carburetor is upside down as well. So naturally the fuel wants to flow out. I put a shut off valve in the fuel line when not used and when starting, turned it open and shot a burst of starting fluid up into the carb. THEN, pulled the cord to get it started. Once it started running, all was ok. There-in that was the major-ist? problem I think I had. Wish I could've figured out a way around it, because it more, or less, had to be that way because of the direction I needed for momentum. Well, I think thats it. I will be around if there's questions.

Oh, this project came in at under one hundred dollars. A donated 20 something year old chainsaw, five dollar scooter with wheels (yard sale), two fifteen dollar tires (new), I think ten dollars for the used J. C. Penney bike (yard sale), used gas tank (had), bought v-belts, fuel line, starting fluid, brackets, screws, eye bolts, 2 pulleys and the plastic/steel epoxy. What a bargain, huh?

Oh and the answer to what happened to the Hub? Well the hub itself had oil in it and had gradually over time seeped out and got between the bonds of the epoxy and came loose while ridng. Very scary. Thats when I discovered that the little kids 12" bicycle wheel would work. I kept thinking I really am having to much fun with this and I gotta get it going some how again soon. And everything fit. Yahooee.... :)



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    55 Discussions


    5 years ago on Introduction

    If I had to do it over I would skip the belt and go with a chain set up. But the problem was the bike chain and sprockets didn't match the chainsaw sprockets. That's mainly why I went with the belt. I do remember the smaller sprocket with five teeth was a pain to convert to the sprocket.


    5 years ago on Introduction

    Fintin, see my comment on Sept 5, 2007. I found a small pulley that fit on the chainsaw output shaft. I drilled five holes in the pulley, spaced the same as the teeth and bolted it to the sprocket. I forgot to mention that part in the instructable. It's been at least seven years ago now. I do remember buying a large pulley and a small one.


    5 years ago on Introduction

    Gadgetman: great thinking outside the box! However, I can't find any instructions on how you connected the pulley to the chainsaw - or am I missing something?

    I had plans to add a pop up seat but never got that far, because the chainsaw's plug wire broke off at the magneto. There was no problem with the direction of the 3spd hub, just the chainsaw had to be hung upside down to get the drive direction I needed. That made it difficult to start , had to use starting fluid, because the carburetor was also upside down.

    you know you can rotate the carburator right? well so the motor was turning the wrong way? i am not sure if i am understanding you.

    If you look closely at the top larger picture you'll see that it's mounted upside down for two reasons. 1) because the chain/sprocket is on the back side and 2) the direction of it has to be bottom backward and top pulling forward for it to turn the sprocket in the right direction. Doing this puts the carberator also on the backside upside down too. The carberator is not capable of reversal.


    Reply 8 years ago on Introduction

    Thanks for the heads up.  Didn't know I misspelled it.  Didn't even know they were still made, considering it was from a 30 something year old bicycle.  Couldn't find prices on them are they real expensive now?


    12 years ago

    Sorry I do not have any video, but I did add a pic of my son riding it, when he was ten, or so. I wanted to make a gas scooter for a project that my son could help me on. I wanted it to be different than any thing else out there and when we first built it I used a Poulan Weed Eater engine. But I couldn't get it started on the ground so I made a plywood block with cut outs for the pegs to sit in and would get it started that way. But everytime I set it down on the ground It would stall. It would piss me off, till I realized why. You'll laugh. It was because it did not have a clutch on it. Dooh! So, basically it would not idle on the ground it just wanted to go. So at that point a neighbor saw my dilema and gave me his old chainsaw. Wow, what a difference, a clutch makes. I was still on the learning curve. :) We rode that thing to death. Its pull cord broke and I replaced/repaired it a couple of times, and I let someone else look at it when I couldn't figure out (the last time) why it wouldn't start, and the guy broke the spark plug wire off at the magneto. Like I said it was twenty something year old chainsaw and I couldn't find any parts for it. So I built another one with a Ryan/Ryobi weed eater. This one I mounted on the front wheel. It wasn't very professional the way I mounted it. It was much different and actually quite stronger on take off than the chainsaw one, because it was friction drive, right on the front wheel. It was difficult to ride because I was having trouble trying to figure out how to get it to clamp down tight to the wheel and release to coast and stop. So what I did was kind of ride it side saddle like. One foot on the rear patio and the other pushing down on top of the motor. It was a stretch but quite fun. Well, till something happened. The way I designed that one was I mounted a stunt foot peg(the knurly kind) onto the engine shaft, but to do this I had to remove part of the housing around it. You see the blower is right behind where the shaft comes out. The housing holds the sucked air in thru there and blows it around the engine to cool it. I took out some of that housing which left the air fins exposed. Well guess what happened. I'm cruising along around twenty, or twenty-five miles an hour, going around a curve and I hadn't noticed that the fins were actually also rubbing against the side of the tire. I'm riding along and Ka-Pow the front tire blows out and I held on for dear life and managed to not wipe out. Scared the crap out of me. But it was a blast to ride too. I had the red chainsaw scooter on TSI's Scooter World for a long time and the site kept moving but I did locate it yesterday. Its still on there with many others. I haven't gotten a chance to look at the new ones since mine but as far as I know, no ones made one quite like it yet. I will check, tho. I also started another one, but with a larger scooter. Did you know that they make adult push scooters. The frames are much larger and they have 14" wheels on them. I bought one used for you guessed it $5 at a yard sale. I didn't know they existed. I don't think I have it now tho, because I moved and I didn't want to bring all that stuff with me when I moved, so I left it. I guess its all at the junk yard and gone forever now. Boo Hoo. : ) I am planning on making an electric one now with the frame inverted on another one like the red one. Will let ya know how it goes. Out

    9 replies

    GadgetmanKen, why waste your time to build a scooter ?there are a lots of high quality & good looking gas scooters in the local hobby shops,on the internet...and most of them the price are pretty resonable,visit the page : I'm pretty sure you can find a good one with great price,save your time,and spend more time riding scooter with your son than making scooter,have more family fun !

    The fun is making your own! Once I have pats lined up, I will be posting an instructable for a 2.5 HP monster scooter that you can't buy at any shop. I've ridden those scooters, and while they are fun, they do not have any speed or power to speak of. The joy is in knowing that you made it yourself. If he just wanted to buy it, then why even try it? Besides, ideas like this made those scooters possible in the first place when some goofball put a weed-whacker engine on a scooter just for fun...

    I believe you will not find another like this one in a scooter store, or elsewhere. My son was there most the time as we built it together. I can say the way it handled, and the ease of the ride, was by far better to those stand on platforms with you ankles all twisted, and was not my idea of safe and fun. With the body of the scooter between your legs is a lot more stable and relaxing. It was not time wasted my friend, but well spent building and riding with my son at my side. Did I mention it was built for under one hundred dollars. Scooter cost 5.00 at a yard sale, chainsaw given to me, bought two pulleys, modified them myself. Bought a belt, well actually two trying to get the right size and bought two Impac low profile tires at a bicycle store for 15.00 apiece. The brakes on the scooter had to be remounted on a new plate because the frame was widened to fit the three speed hub. Now, if I started with new stuff including scooter, it would have beeen in the price range of the new fancy scooters you've mentioned. It was definately in my price range and most definately worth the effort and time I spent with my son building it. Also because It was one of a kind. Very unique. If I had the money to buy one I would still flip the frame and use better parts for sure. Could you build one similar for that price?


    Trebuchet03 I was wanting to build something different and had turned the frame upside down on a scooter once and put pegs on the rear wheel to stand on and just said hey I want to power this somehow. I had actually started with a weed eater, but later after much work realized it didn't have a clutch and the wheel had to be off the ground to get it started and made a frame to do that , but it still needed something else like a clutch, because as soon as I set it on the ground it would try to take off or stall. I did build another one with the frame inverted with a weed eater on the front mounted above the front wheel. It was friction power IE: my foot pushing down on the motor and the other standing on the foot peg. Side saddle if you will. Just like those other stand on platforms, but with a much wider stance. It had good get up and go, for sure with me on it at about 215. But I was riding along about twenty miles an hour or so and the front tire blew out and I almost totally wiped out on concrete. The weed eaters air fins had been rubbing against the side wall of the tire, ate through it and blew out. I hadn't realized it was doing so. Scared the crap out of me. My son now has a goped type scooter with the stand on platform and has already wiped out in gravel and broke his risk. So there's my point. I always made him wear a bicycle helmet too.