go-kart

[sprouticus]

I have an old gokart that a friend made. It used to run off of a started motor for a car, but thats dead now. I've been playing with the idea of hooking a chainsaw motor up to it. I've already replaced all the fuel lines in the chainsaw, and gave it a tune-up. I got it running pretty good. My question is........would it have enough power if I made my axel sprocket 4 times bigger than my engine sprocket (right now it's about 3-1 for the starter motor, and 2-1 on the chainsaw.)

I'm thinking I have to buy a new motor.

I've also had it suggested I buy a starter for a big diesel or something.

 

[Bob_VT]

Re: go-kart

Probably not enough torque....

It used a started motor so are you saying it is electric? Starters have tons of torque..... look for an old electric wheelchair motor

 

[Windykid]

Re: go-kart

The chain saw motors will just burn up cluthes, I know I already tried it on my bar stool.

 

[sprouticus]

Re: go-kart

yes it did have a starter motor. It ran off a 12 volt car battery, and it probably got up to 50 kms/hour (about 35 mph) It had a switch, so you could turn it on or off.........I was thinking about putting in a rheostat (dimmer) to control speed. It worked fairly well, but those motors are not made for a continuoues load, and it burned up. I got a replacement, but I am not sure it's even worth the trouble. thinking I'm going to get a 6.5 horse motor thats on sale.

thanx for your input.

now........any ideas about brakes?????

 

[Bob_VT]

Re: go-kart

Just google go kart parts. Just about any add on disc brake attached to the axle will stop the cart

 

[JB]

Re: go-kart

I used chainsaw engines as the base to build engines for my racing Karts 50 years ago, Sprout. But:

Those engines were 5 to 8 cubic inches and turned about 4,000-5,000rpm in stock tune. I haven't seen a modern chainsaw with greater than about 3 ci. and they seem to turn more like 8,000-10,000rpm.

After modification my engines turned 12,000-18,000rpm on methanol/nitro fuel and were geared 6-10:1 to the axle with 10" tall tires.

I think a modern chainsaw engine would be a pipsqueak. You would be far better off with a 4 stroke mower engine.

 

[sprouticus]

Re: go-kart

JB, I'm fairly mechanical. I'm actually nearly done my electricians apprenticship, but you my friend I believe have done it all.

The only reason I wanted to use the chainsaw engine, was because I was given 2 of the without a bar or chain, and I managed to get one running fairly well. I went out today and bought a 6.5 horse engine (196 cc 4 stroke) and a clutch to go with it. I have seen those brakes someone mentioned on e-bay, and i'm thinking of going that route, but i'm not crazy about spending another 150 bucks on this cart. by the time i'm done, I will have spent more than what I could have bought a used go-kart for at the local track, or bought a cheap knockoff brand new.

I've thought about rigging up a drum of some kind, around the rear axle, and putting a tensioner on it to use as a brake. they sell something like that too.

still thinking....I have another month before I have to be in the painting stage.

 

[sprouticus]

Re: go-kart

alright...........so I conned my drunken buddy tongiht into calling up his FIL and asking to use his welder. We grinded off the rear axle mounts and flipped it around 180* because the sprocket was on the wrong side in the new motor. Then I used some cantruss to build a bracket to hold the motor. Tommorrow i'm off to try to find a store in town that will be open that carries spring nuts, to mount the motor to the cantruss.......if not I have to wait till monday when I go to work. after that, I need a new chain as the old one isn't long enough, and then I'm ready for a trial run.

still thinking about my brake issue though, as now that i've re-welded the back axle on, it's too late for me to buy a rotor and calipers. thought about that too late, and I don't want to do it again. I'm working on another idea, but I'm still open to suggestions. I'm thinking a "U" shaped piece of metal lined with rubber on the inside of the "U", thats pulled tight into the drive axle when you operate a lever may at least slow me down pretty good........I'm not expecting it to lock up the tires, but it may help a little.

 

[JB]

Re: go-kart

You really need to be able to stop that thing before you start it, Sprout. I'd hate to see your obit in the SHT forum.

 

[FLATHEAD]

Re: go-kart

A motorcycle disc brake would be ideal. Mounting the rotor and caliper would be a piece of cake. Then just a matter of some yankee engineering to set up the master cylinder and petal. Good luck and please dont ride the thing without GOOD brakes.

 

[puddle jumper]

Re: go-kart

A lot of go carts Ive seen use chain saw engines for power and the brakes are made up from a automatic transmission sun gear drum and band brake ( which is often the kick down band from the trans).

 

[sprouticus]

Re: go-kart

well, I couldn't find the proper chain for sale in this small town on a sunday. None of the dirtbike places carried it, and the industrial supply places were not open.

I was originally thinking of using the brakes on the chainsaw motor, with something else as a back up, as I didn't think they would be that good, but the chainsaw idea is long scrapped, I've got the 200 cc, 6.5 horse engine now. what if I used the band that I've seen for sale, and mounted it so that when pulled tight, it would cause friction on the outside of the clutch?? I'm not even sure there is any room on the rear axle to mount something, even if it didn't mean i'd have to undo a days work to get at it.

other ideas i've had is using a bicycle type brakeing system on the front tires. and of course the easiest would be what I used for brakes when I was a kid, a lever that applied pressure to the left rear tire when pulled. mayeb something to that regard that is foot operated, but applies pressure to both rear tires??? I don't know, still thinking.

sorry JB, I know your advice is very good advice, but I know myself better than to say I won't be riding this thing if the only things left to do are brakes and paint. I will promise to find a deserted road, and not open her up all the way. I have to test it before I had it over to my kid right???.........lol.

 

[Kenneth Brown]

Re: go-kart

As a kid I built a brake that worked very well. It wash a small piece of flat plate that mashed against the tire itself. We had it fixed as both foot and hand lever controlled. You might look into something like that.

 

[sprouticus]

Re: go-kart

yeah, the lever and friction against the tire is the best idea so far......easiest anyway.

so, I got the engine mounted today, and a chain on, but I'm going to have to raise the engine with some spacers or something, the cahin was a little loose, and fell off on me a few times. It was going pretty good, but I didn't ride it long, with the gearing set up the way it was, that clutch was getting damn hot, and I didn't want to burn it up. ordering a new sprocket for the rear tommorrow. I've already talked to a real welder at work to put it on for me, (cause I'm just going to cut it in half, and weld it on to the exsisting sprocket).

it's too bad the chain was loose, I'm guessing it was probably doing 30 clicks before it fell off, i'm curious how fast it would actually go, cause it was still picking up speed, and the engine wasn't close to winding out.


not until I get breaks though.

i'll post pics when it's all done.

 

[warlordxx]

Re: go-kart

I'm doing a kart right now but useing a ski-doo 340 motor ( stock 35hp ) and drive.... for brakes I'm useing the ones off the front of a 80's honda 500 sport bike. I dont know what your axle is but mine is 1 1/4" and you can get hubs off ebay to fit the axle and disk

 

[bhammer]

Re: go-kart

I used to make them as a kid and race comp. I always bought my chainsaw engines that were off old commercial logging chainsaws. With the largest one I made, dual engine, at 125CC ci ea, it could get the cart up to 105 in a matter of seconds. The dual was great for the torque needed for turns in the hills and trying to get up and go. After the mods to the engine and running nitro, I'd turn 15K easy. I guess me and JB had the same hobby. I used to use a disc brake setup off a motorcycle for stopping. From there, I went into building drangsters with modified 5HP engines running about 85MPH but I had more fun with the carts as there was more to do driving.

On the swap, you can run a slip clutch that will handle the gearing for you instead of trying to figure out the right setup. I used to have different setups depending on the course and the need for quick starts off turns or long straight runs.

 

[sprouticus]

Re: go-kart

lmao. I think some of you are thinking this project of mine is a little bigger than what I ever intended. Originally, this was intended for my five year old to drive for a couple of years (doing maybe 10 mph tops), and when he outgrew that, I would put on a bigger motor. I am convinced the cheap little chainsaw I had would never do a good job, so I got a 200 cc motor. This is not intended to ever be in a race, win anything, or break any speed records. It's just a little toy for my son when we go camping, and maybe something I could jump on to take my dog for some exercise around the block. I'm jealous of all of you that built much better karts when you were kids, but I don't have those skills, money or time.

WHen I was a kid, I built a go kart enitirely out of wood and re-straightned nails, that the front axle was on a pivot, you used your feet and a rope to steer. the brakes were a lever that rubbed against the rear tire, and I had to drag it back up the hill if I wanted to ride again. I dreamed of having something with an engine, and an actual steering wheel, so my kid is already better off than me.

I also orriginally intended for this whole project to cost me like 100 bucks, mostly building it out of scrounged materials, or things I could beg, borrow or steal (ok, not steal, thats wrong........maybe a few nuts and bolts from work, but thats it) I've already tripled my budget, and a decent go cart breaking system is gonna cost another 150+.

I appreciate the input from those of you who have built rocket powered, go-karts that could do the quarter mile in under 10 secs, but this is not what I am all about.

my new sprocket is coming in tommorrow. the few test drives I've had so far has left the clutch smoking hot, and it has very little bottom end right now. according to my calculations though, mathamatically, It is capable of 171 km's per hour. (thats like what?, 120 mph?) the way it's currently geared. It will never actually do that, except theoretically. It gave me a chuckle when I did that math!!