That was the problem. He was using a chainring setup designed for multiple gears with ramps to shift. If he'd used a singlespeed chainring and cassette gear and chain it wouldn't have slung the chain.
Hugo chen most single speed chain rings have a “narrow-wide” design on the teeth, its superior in keeping the chain on. Chain rings from a 3 x setup have narrow teeth that allow any amount of lateral force to shift it
Dear "This Old Tony", Firstly, I hope this gets through to you. Secondly, I want to say thank you so much for the time and information you've put into your videos. I am an "import" living in SE Asia where I have no chance to learn this kind of material, but your videos have been teaching me how to become a better machinist. I truly mean it, you have helped me learn what would be impossible otherwise because I have no opportunity to go to school where I live. Anyway, I want to help with what I can. I am a scooter mechanic by trade (of 6 years or so) and I work with small engines every day, so I am very familiar with...well, small engines. Since I can't do much to contribute monetarily to your channel, I wanted to help you with some information that I believe might help. 1) Those bicycle gears and chain are not going to hold up. Ignoring all the complex maths (yes, Brit speak), even a mild electric assist mountain bike (1/2 - 3/4 horsepower) can snap regular bike chains and cassettes, so a 2 1/2 horsepower motor would be way too much for them to handle as you've seen. So I'd forget using bicycle parts altogether, although I know you've fabbed stuff already. Sorry but, just my suggestion. It's not the play in the clutch (motorcycle pinion gears have lots of side to side play), but just that the chain and gears themselves are too weak. However, there is a very cheap and durable solution, check out "Pitbike" gears and chains for a range of very cheap but strong (enough) gears for your drivetrain. Even the smallest 420 pitch chain, pinion and wheel gear are enough for 6 - 8 horsepower applications (about 4 times more than your motor at max power/torque). Cheap import chains are just fine and will take all the power of the mild tune chainsaw motor you can throw at it. Of course the gears will need to be machined to fit the axle/output shaft etc, but I suspect that will be no problem for you. 2) That small motor likely is going to burn itself up very quickly because it probably uses a plastic camshaft and possibly followers. Not much you can do about that, but just thought I'd make that heads up addition. 3) When you install the engine to the final gear, scooters use what we call a "cush drive", essentially rubber inserts that the dogs of the spur gear uses (sorry, hard to describe) to absorb the shock of stop and go throttling. Look up motorcycle cush drive and you'll get an idea, very easy to fab up a drive unit, even for me with a welder and basic hand tools. Interestingly, just the addition of these rubber drives it greatly not only extends the life of the chain, but the engine as well (as the engine interal parts don't receive that jolt from on and off power). So for the drive, I would recommend some kind of damper. Anyway that's just a few observations and tips I can offer. Okay, hope this reaches you as your help has been invaluable to me and I want to contribute what little I can from around the world Thank you much from SE Asia Mini Motor Man
Jip here´s another sucker that is gonna be very tired tommorow at work ...i have to see them all in one go now .. Grtzz from the Netherlands Johny geerts
This was fun to watch. I am 57 and have wanted to build a gokart since I was 8 years old. A couple of years ago I bought a 6.5HP motor, but still haven't got to building it yet. I am thinking I will be in my 60's when I finally rip it up in a gokart. Fortunately I am still a kid at heart. Cheers
Some day you will make a great dad as well. You know what not to do. My Dad wasn't perfect. That being said his Dad was an abusive drunk so he was better than that. I'm trying to be better than mine.
Just found your channel by accident. ..I'm hooked. Your ability to use the bender you have, your welding skills, and lathe skills. ABSOLUTELY AWESOME. Thank you for sharing with us.
I am a manufacturing engineering student at Cal Poly Pomona, and took courses on milling, turning, casting and welding. I learned a lot from your RU-vid. Channel especially on tune bending. Your cart is coming out nice I am enjoying all your projects and tutorials. Excited for the final product.
You are a great Dad. When I was a kid my Dad made me a bike from spare parts,It had a big tire on the back and a little tire on the front. I was cool, that was 55 years ago and I think of it all the time. I really like your little go cart. Big thumbs up!!!! M.K.S.
Here I thought I was a good fabricator, you my friend are an amazing fabricator! FYI- I put a chainsaw on a skateboard when I was 13 years old. It was an old McCollugh and I used a Hoover round rubber vacuum cleaner belt and cut a groove on the rear skateboard wheel chucked up on a drill press. Yeah, the belt slipped on the clutch sprocket but once you got going it was fun, scary, and loud!! Thank you for your channel. It’s therapy watching you work when I don’t have the time too!
When i made my first chainsaw bike, and was young and not so expirienced. I also tried bicycle chain, and figured out 10sec later that it wasnt gonna work. I then switched to bike chain and had no problems.
I know this is now a historical video, but I've been so impressed with part 2. A proper cut and shut, too. Respect. Reminds me of the simple wooden 'pram' go cart that my granddad made for me, which had lots of iterations. Sort of Toyota's 'kaizen', but we just fixed lot of breaks. My go cart was gravity powered but had a rear brake and was a lot of fun and very solid, but simple steering. This video reminded of it, which I've not thought about for ages. Cool work, TOT.
remember that most steering geometry info is for vehicles with suspension and relatively soft tires, that is the chassis moves relative to the steering pivot and the tire flexes significantly so the caster and camber are set to help cancel out the negative effects of that movement. Also the dynamic effects are going to be different from the static effect.(eg. what feels heavy stopped may be just right in actual cornering) Toe in is used to remove the slop in the connection linkage during forward motion[when the ground is pushing the wheels back], more in-toe dampens, removing wandering and twitchy tendencies, too much causes tire wear and a sluggish response.
That long output shaft on the CVT looks like its going to be quite hard on its bearings. I recommend shortening it or maybe supporting it somehow. With such a small sprocket on it, that shaft is going to see quite highish forces and get alot of leverage.
I thought this might be a problem, but I also thought the run-out on that sprocket was significant. Feedback via the chain could really be a hassle down the road, I think.
YOU DO GOOD WORK, EVERYONE LEARNS AS THEY GO!!! YOU ARE LUCKY TO HAVE A LATHE & A TIG WELDER!!! I am slowly accumulating tools & want nothing more then my own garage/shop!!! As a child, I had a go-cart & it had twin engine stands & twin sprockets! WISH I STILL HAD IT!!!
that is a very strange and interesting frame design. my simply go kart was just 1/4 inch steel tubing bent into a square with a box at one end to hold up the engine. there was a piece of a sheet metal welded inside the square for the seat and for stability. basically it had no "sides" like yours does (it had a fiberglass shell that sat on the frame). i recomment welding in a piece of sheet metal for the floor of your go kart because it will protect your kids legs the best, and mounting the seat will be easy. i also recomment putting a kill switch grounded to the chasis under the seat that your kids can easily reach. i had to hit my kill switch a few times very quickly when the engine had issues or when i broke a chain or unseated a tire
This is much more of a space frame design like you'd see in a kit car (albeit with square tube instead of round). I believe he mentioned wanting to go for a space frame in part 1. Gives great strength for weight. Upvoted and commented because of the kill switch. 100% good idea. I can only assume he'll be putting a sheet floor in there already, but the kill switch could be easy to overlook.
before i knew anything about electrics in cars or go karts, i used to think the kill switch was magic because it only had one lead running out to it haha. i wasn't familiar with the term "space frame" until i read your comment. i've known about the usefullness of trusses and triangles, but now i have a word for it
That yoke; you can call it a King-pin bracket. If anyone is interested in making sich a go-kart it's to good to dive in these principles as well: Ackermann, dive and squat of the suspension, chamber, caster, king-pin inclination (as in the video). Its looking like a cool video Tony, very inspiring! And very enjoyable to watch!
Rob M I've seen other people on RU-vid run the chain straight to the drive gear and they seem to work fine? They use a chainsaw engine and I'm honestly really confused why it didn't work for him?
chain tension is the biggest culprit , especially on #25 chain or TF8 bike chain .. Tf8 also requires perfect alignment , since a lot of those rear gears are meant to discharge the chain during gear changes on a bicycle. You pretty much need to start with the chain piano wire tight , and let the natural chain stretch happen to get it " just right"
Silent, old chainsaws were 125cc like a kart engine and can work at 6:1 reduction, but a new chainsaw with tiny 49 - 50cc engine needs about 15 - 20:1 reduction with a jackshaft setup to increase the reduction...
wow that is one sweet frame that you built ! Your kids will be spoiled and it should last a long time as well !Haave you thought about adoption ? I'm potty trained and I really want to learn more when it comes to the lathe andd mill ! I a a good learner and know how to sweep !
Tony, I think your caster and camber angles are far too aggressive. A normal road car has around 3 degrees of caster and .5 degrees of negative camber. With king-pin steering, the camber should be set so the scrub radius of the tire is minimized; the kingpin centerline should continue to the centerline of the tire, so the tire doesn't scrub when turning. This can be accomplished through a combination of kingpin inclination and positive camber at the tire, or increased kingpin inclination and zero camber. I wouldn't add a bunch of caster or camber, 6 degrees of caster is probably good, you want the steering to be light enough.
The caster angle is definitely aggressive, but the camber is essentially zero - it has nothing to do with the angle of the kingpin, but the angle of the tire, which in this case looks perfectly vertical to my calibrated eyeball. What he called caster was actually the steering axis angle, which does nothing but change the scrub radius.
Don't forget that unlike a road car the kart has no rear differential, only a solid axle. This would make it difficult to steer properly so you need a good level of caster to lift the rear inside tyre off the ground and allow it to slip around the turn. Caster tuning range (on a kart) is 8 - 20 degrees, with 20 giving more lift, but heavier steering. I would start at 10 degrees for children to be able to turn the steering wheel.
You do realize that the first "Go Karts" used chainsaw engines. The engine of choice was the McCollough because of its high rpm and 6 hp. At least that's the one I had. Poulan wasn't even in the running, Homelite was the second choice.
The front "U" shape bendy thing is called a STEERING KNUCKLE. It contains the KING PIN you made that connects to the axle that pivots the steering wheels so the cart can avoid the mean mean trees. Love your show. Laffing my head off every episode. :-)
Hey Tony, nice build. On the camber angle when you welded on the wheel spindles, and placed them parallel to the ground, didn't you essentially negate the camber angle you'd just installed onto the bracket? If you when you think about it, when you adjust your camber on the car, the wheels move with it. I think the spindles should be perpendicular to the brackets they are welded onto. Just a thought
Chain problem is because you put the idler pulley on the wrong side! You have it pushing against the power transmission side of the chain (section moving upward).. the engine power simply shoves your idler back loosening the chain. Instead lose the idler completely, tighten the chain by moving the motor (like on any racing kart).. or remount that idler to push on the other downward moving section of chain. Also, keep it simple, use a larger axle gear and a much smaller engine gear .. you probably want around 6:1 or 7:1 ratio for a motor like that. Most racing 2 stroke karts use a clutch gear that is the smallest which can possibly be used (9 tooth #35 or 10-11 tooth 219 chain). Yes, 20 deg caster is way too much on king pins ... for a kid kart and low speeds, I'd go for a very low caster nothing larger than 12deg and maybe much less (5-8 deg) .. will make it easier for your kid to turn the steering wheel.
All very good points. Question about the idler. I don't see that it's on the wrong side. I may have missed something. I'm glad an expert said something. It helps tremendously. Oh, btw, I think it's throwing the chain because the motor is wobbling around. When I saw the first video I didn't like that mount. It's for holding the chain bar. Never meant to hold the motor. I see other points on the motor that might be better to anchor it from.
I'm building a few chainsaw/mini Moto go karts this year, that engine kit you got was a sweet deal. Wheels and steering components is what I was looking for so thanks for showing all the bits and bobs. ATB Darren
robertas grigas I knew it was just too great of a deal to be true.! interesting how the manufacturer used some deliberate designing to further create the illusion of a cvt tucked into that cool cover. I wonder why there isnt a cvt set up being produced for these motors. it would be great on a motored bicycle instead of the cheesy hand clutch arrangement that is the weak link in those ebay kits.
Rob M man, if you told me seven years ago that I'd be this excited for some old tony on RU-vid, I don't know how I would have taken it. Come to think of it I'm pretty sure some further time travel paradoxes would need addressing.
Hey Tony I have a little experience with mini quads and pocket bikes and I don't think you have a cvt. They take up a lot more space. It looks just like a ~3 :1 chain/sprocket reduction. One end is connected directly to clutch bell of a typical centrifugal clutch. I've been thinking about a small engine gokart for a few years now. Really enjoying these videos. I need to get a bender like that.
Looking really good now Tony ! If you reverse the steering yoke sub-assemblies (e.g. at 07:22) it gives more space for the steering arm to articulate. So the yoke has a stub axle welded to it and the vertical tube is welded back to the main frame, usually on a short outrigger tube. If you are chopping them off the frame anyway, then you may want to swap them around so they work the other way. Don't forget the Ackerman geometry and point the steering arms inwards slightly to point to the centre of the rear axle (as seen in plan view), not just straight back. Also , I'm sure they are just place holders but stiffen up the engine mounting rails A LOT as they will get pulled down strongly by the chain load and throw the chain. Finally don't put the fuel tank directly under the child's hair. Good work . . . eagerly awaiting part 3
Very cool build! A good Tig weld is like art work that I could stare at for hours. Looking forward to installment #3 of: "As The Go Kart Builds". Take care!
your frame design would be a lot stiffer if you made it like a truss, and made sure that all sections of it are triangular shaped. The triangle force each member to be in compression or tension. You could easily modify what you have my adding some more diagonal pieces to make 'triangles' along the length of the frame
This was the second video of Tony's I ever saw, loved it then, love it now.. Thanks random RU-vid algorithm for suggesting this again.. 😁 Happy new year ToT.. 👍🍻🎇🎆
Tony, that is turning out beautifully, I really like watching this as I started a go kart project just before high school about 6 years ago, I had a lot of trouble and it took me so long that every time I came back to work on it I would be irritated with my past design! 😁 I'm really enjoying this series, your boy is going to have a phenomenal time with that! Good luck with the rest of it!
Great job Tony! Growing up I always wanted a GoCart. You did an amazing job. The only thing I would have wanted on mine different. Is I would want more power... lol 250 - 300 cc. That opens up a ton of engineering challenges. For the kids this is perfect. Again great job!!
Lookin' good Tony. Don't forget to apply the Ackerman principle in episode 3. This whole steering linkage geometry thing makes me think back and laugh at myself as a kid. First go kart I built, ignorant of such things, just snow plowed in the gravel instead of actually turning. A hard learned life lesson at a tender age, and was a real head scratcher of a disappointment. Thanks for the memory Tony. LOL
man i want a metal lathe so bad even a wood lathe would be awesome so many projects i want to accomplish btw im a new sub just found your channel this morning. Your funny.btwnot thatthis is relevant but i build and make illusions for Professional Magicians.
The youth center i went to as a kid created two Go Karts from lawn mower engines. I helped build the second one, but I was 13, so I didn't get to do some of "fun" stuff like welding. :D They were a lot of fun to drive.
Necro post, but great series. For future reference, 15 degrees of caster (the amount the kingpin leans back toward the rear wheels) is a nice generic setting that gives a nice amount of self centring without too much steering weight or steering lift. You'll want the king pin to hit the ground a little ahead of the front wheel's contact patch, if you extended the king pins to the ground. For king pin inclination, a specific angle isn't important. What IS important is to try to get the king pin to virtually extend and hit the ground roughly in the middle of the tire tread. This will help give the kart a nice neutral steering feel.
I recently threw away an old chainsaw. Afterward, I thought "maybe I should have saved it to try to make a motorized bike." Now I think I made the right decision, so thank you :)
Racing karts run two stroke engines which spin up to 16000 rpm. On a lot of them the drive is direct with 1:7 gear ratio. Crank shaft gear and axle sprocket are much stronger than bicycle sprockets as well as the chain. Chains for these can get quite expensive. But the key is to actually keep everything loose because the chassis, axle and engine will flex. The axle bearings are special type that are designed to move to some degree in their cassettes which attach to the chassis. And, since there is no differential they really don't turn very well in tight turns and slow speeds. I believe some of the store bought kid karts only have one wheel drive to avoid this problem.
A great looking go cart Tony. I just think its a bit heavy duty. coulda used tubing for rear axle and the couplers for the front to back frame connections just to name a few lighteners. Now you can build your kids an airplane for a encore!
This is a really cool project, I'm enjoying being along for the ride :) A worm drive won't work though. The wheels will lock up instantly as soon as you back off the throttle.
HI, very cool but one super important thing. That chain is pulling like way more force then you think. That chain saw with its cantilevered mount would never work, but could be solved by putting a link between the saw shaft and the axle. same with your new motor. I calculate around 1000 lbs tension from the 1" sprocket assuming 2.5 HP and 300 rpm for final gearing. I bet you snap that aluminum housing in two without a support. Put a bearing next to the small gear on the shaft then a bar from there to a bearing around you axle to take all of the tension. Just saying... good luck!
The theory of steering geometry For a neutral setting the centre line if the "kingpin" should intersect the centre of the contact area of the tyre this allows the tyre to rotate about its centre altering the "kpi" king pin inclination shifting the intersection point outside the tyre contact centre point or positive position will create over steer moving it to the negative will give understeer. Normally everyday cars have negative and sports cars have positive which is why sports cars and not so good drivers end up spinning out so much I love the work you do and the way you present your videos ... long may you rock....
This was well timed. I'm about to re-do the steering on my go-kart. Probably read similar things to you. The 10* and 20* figures sound abut what I read.
Beautiful work. You seem to have no Real plan but very capable of changing ideas at any time. It looks good enough your grandkids will even be able to enjoy it !!!
i like how he goes through all the trouble to look up how to set caster and camber, then promptly negates the camber by mounting the axle stud parallel with the ground.
Get an actual clutch with a proper #40 chain sprocket. Leave off the jackshaft and go direct to the axle. In the 60's the local gang of speed jockey's were hitting 80 mph on a oval track with 100' straightaways.
I always squint and turn my head away when you are welding. Good habit, saved my eyes many times in the workshop. A bit annoying while watching a video though.
I haven't read all the comments which probably has hit on the chain problem by now but in case not the bicycle sprockets are the problem if you think of it they are designed to jump the gears so to speak. Great video work.
from a chainsaw engine to a 4 stroke motorized bicycle motor. kinda neat to see a motorized bicycle motor used in a different way mainly because i build motorized bicycles
Awesome video! I've always wanted to make a go cart out of a chainsaw or a weed Wacker motor, some small 2 stroke. There's more than one way to skin a cat. Great job
i was happy to see this engine substitute. i watched the first half thinking your building this beautiful, machined sub assembly, to hold an old pos chainsaw. ccant wait to see how this turns out. im going to b devastated if you never finished this...
I enjoy this sort of thing with my daughters... no father for me growing up... didn't miss it... just didn't have it. I still made my own projects and learned from experience instead. It gave me independence... =D
I hope you have enough weight or traction in front. that's one thing I learned the hard way. messing with carts with live axels. if there isn't enough grip in front . and too much in rear. its not doing to steer. but it looks like the rider is close enough to the front for the weight to help with grip. now its up to the tires. the frame looks awesome. I wish I had something like this when well now... I'd like one now and I'm near 40! if I has the tools and shop to work in. and its awesome you are building it for the kids.
This old Tony- you need a chain guide where it enters/exits the sprocket. Just like the bicycle you took the gear sets off of. All chain driven equipment uses guides to force the rotation into the set.
Loving it! But good heavens you have to support that engine's output. The overhang is colossal on that thang. I think the cast alu CVT case will twist/break immediately once the chain is on and you hit go. Shortening the output so the leverages aren't such hell might be a neater solution. Everything you've done yourself is class. Of course it's the one bit that's off the shelf which has sucky design! Keep being awesome!
