Building 1st Kart ... NEED YOUR HELP

[Budc]

I am a 77 yr old man who is building my first go kart ( wooden 6' long) with my 12 yr old great grandson that will be driven on asphalt and concrete 80 % and grass 20 % of the time.. I have a Harbor Freight Predator (212cc, 6.5hp, 4 cycle, 3/4" shaft, 3/16" keyway) engine for it. I plan to leave the governor on it.

Now I need help .... I want to buy 3 floater tire and rim assemblies, and one tire and rim assembly with sprocket .... what size tire and wheel would be ideal? Should front and rear tires and wheels be the same size? What type tire would be best? Would 10 /60 teeth on small/large sprockets be correct?

I plan to use the square tube/bolt method to mount front tires.... will that also work to mount the rear tires???

Any advice on what to look for when buying a centrifical clutch for our engine?

What # chain should I use - I've been told to use a #420?

I have made a wooden braking system that contacts both rear wheels - hope that was a good move!?

Do I need an metal engine adjustable mounting plate or can I slot holes in the wood frame?

Best way to install a throttle?

Where is the best place to get my needed parts? So many places online to choose from!

Anything else that you can suggest?

I really thank you so much for any recommendations and advice that you share with us. Thanks again.

P.S. (This old woodworker probably should have just purchased a completed go kart!)

 

[jonlasaga]

Sounds like a fun project! I have only ever made one wooden kart before but it did give me an idea of what I wanted to do differently my second time.

As far as tires: split rims are very nice because they make changing tires much easier. When I built mine I used harbor freight 6 inchers and they worked pretty well and even came with holes to mount a sprocket but were pretty skinny and as someone who weighs almost 200 lb I maxed out the weight that was suggested for them along with kart. I mounted mine with just bolts through the wooden frame and they held up alright not the most durable though.

As far as gearing: 10 tooth to 60 tooth is very standard and suggested by most clutch manufacturers. Usually they also suggest that you stay under 6 inch tires with this setup but you can usually push that bigger if you arent climbing hills.

I dont know a whole lot about CVT transmissions for these engines but I do know most clutches work alright as long as you keep them oiled.

chain: 40 41 and 420 chain all work well and are cross compatible in certain situations. More on that here https://www.gopowersports.com/go-power-sports-blog/chains-of-all-size-and-flavors/

I had a similar braking system where 2by4s touched the front wheels to brake and it worked alright at slow speeds but a live axle will give you much better acceleration and allow you to mount a disc though for a kids kart that is usually on pavement one wheel works fine. On mine though i definitely did wish I bought a live axle.

For throttle and steering on mine I put standard bike handlebars and front forks through the board that handled my steering and bolted them above and below it to keep them from sliding through and attached throttle to the bars using the old shifter thumb button. That was one part of my kart that worked very well.

Good luck with your project. I hope to see some pictures when its all polished up.

 

[Budc]

Jon, Thanks so much for your help .... you have given us some great guidance ! Will definitely share some pics when we 'git er' done'. Thanks again!

 

[itsid]

wooden karts are a very bad idea in 99% of all cases.
making a wooden kart sturdy and reliable enough to be be powered by a combustion engine,
takes way more time money and thinking than making a steel chassis kart.

Wooden scrub brakes wear out the tires and worse.. once they get wet they tend to get soapy (with some help of dirt and rubber)
And no longer have much of a notworthy effect at worse.
So no.. again an idea I'm not actually a fan of.

I know, hard times all over the world, easier to work with what you got laying around ..
all true..
but having your family member severely hurt or worse killed in an accident because of a non functional brake or breaking chassis...
it's just not worth it.

So, steel kart chassis please! if you cannot weld one, buy one!

scrub brakes are mediocre at best... steel plates at least cannot soak water and
thus be more or less consistent in braking power.
No wood there please; but frankly.. a band brake is much better, a proper internal drum brake better than that and a mechanical disc brake tops that and isn'T expensive either..
so rather dial in for safety than for simplicity!

'sid

 

[jonlasaga]

wooden karts are a very bad idea in 99% of all cases.
making a wooden kart sturdy and reliable enough to be be powered by a combustion engine,
takes way more time money and thinking than making a steel chassis kart.

Wooden scrub brakes wear out the tires and worse.. once they get wet they tend to get soapy (with some help of dirt and rubber)
And no longer have much of a notworthy effect at worse.
So no.. again an idea I'm not actually a fan of.

I know, hard times all over the world, easier to work with what you got laying around ..
all true..
but having your family member severely hurt or worse killed in an accident because of a non functional brake or breaking chassis...
it's just not worth it.

So, steel kart chassis please! if you cannot weld one, buy one!

scrub brakes are mediocre at best... steel plates at least cannot soak water and
thus be more or less consistent in braking power.
No wood there please; but frankly.. a band brake is much better, a proper internal drum brake better than that and a mechanical disc brake tops that and isn'T expensive either..
so rather dial in for safety than for simplicity!

'sid

He is definitely right that durability will be your biggest enemy with a wooden kart but I wouldnt say its that much more unsafe than a steel kart. Especially when the kart is very underpowered and geared for low speeds it should be more than safe enough. I crashed mine many times and had alot of fun with it and it didnt harm me but the durability suffered more because of it.

I would also agree that wooden brakes have a very limited life and they smooth over as you would know from being rubbed on which will decrease braking. I would never suggest band brakes over the clutch though because of a bad experience I had where the chain came off and suddenly I could not stop. But if you had a live axel wooden kart with a real brake I would say that could be just as safe as long as the chassis is built with good wood preferably layered as that can help alot.

But I am sure that any adult that is building a kart for a child would make sure to ride it and feel it out to make sure it is sturdy and has proper safety features before they let the young one ride it. As long as you use good judgement, maintain the kart, and do good testing it should be safe.

Then again as a dude on the internet take my opinion with a grain of salt. I dont know everything and have limited experience working on wooden karts as I have only done it once before moving on to steel. And honestly once you have a welder and do your first frame out of steel I doubt you will want to go back either.