Kart Build

[TripleT]

My engine
8hp Tecumseh

 

[TripleT]

My Kart Frame: Murray Explorer
I know the words are backwards but i only had my computer to take the pics

 

[souperman000]

looks good!

 

[TripleT]

Thanks! Got a bit of work to do, I went to start my engine the other day and didnt start along with the pull start rope getting broke. Then i took it off and noticed the plastic piece was cracked. Where would i mount a charging coil on the engine?

 

[TripleT]

And would a 17 tooth clutch with a 60 tooth sprocket on the axle be good?

 

[landuse]

And would a 17 tooth clutch with a 60 tooth sprocket on the axle be good?

Short answer? NO!

That would give you a gear ratio of 60/17 = 3.5:1. That is Waaaay to steep for your kart, and you would not even get moving. Your clutch would also burn out in seconds.

What you need to do is get a ratio of at least about 6:1. This means that you will need either a 10T clutch (which depending on your sprocket pitch you might not be able to get), or go for a larger axle sprocket, like a 72T (again depending if you will have that much clearance before the sprocket drags in the dirt) and a 12T clutch.

You have large tyres, so even a 6:1 might be a bit high. I would probably aim for a 7:1 raio.

Just my 2c ..........

 

[TripleT]

So it would be better if i didnt use a 60 tooth?

 

[landuse]

So it would be better if i didnt use a 60 tooth?

I would either get a larger axle sprocket, or a clutch with a lower tooth count (like 10 or 12T). You need a much lower gearing ratio than what you have now.

Just thinking about it, you will need to get another clutch, because keeping the 17T clutch will mean that you need a rear sprocket with 102T just to get a 6:1 ratio. Otherwise you are going to have to invest in a jackshaft

 

[TripleT]

I dont have it, I was wondering what would be better before i got it.

 

[landuse]

I would probably get a 12T clutch and a 72T axle sprocket. Just make sure that the 72T diameter won't be too large for the ground clearance of your kart

 

[TripleT]

Any way i can get a smaller sprocket? i don't want that low of speed

 

[landuse]

Anything smaller, and you are going to be burning clutches. You have to realise that karts can only do so much. A 6:1 gear ratio with a centrifugal clutch is as high as you really want to go.

Using the speed calculator on the site, I work out that you will make about 29MPH with the gearing I proposed. When riding a kart just a few inches from the ground, that is plenty fast. If you want faster speeds, you are going to have to start looking at a motorbike engine.

You could maybe invest in a torque converter

 

[chris_the_poser]

Landuse is spot on you need a smaller tooth clutch you might be ok with the rear sprocket that's on there but most likely you will need a bigger one a torque converter would work well also

 

[TripleT]

If i had the money to get a torque converter i would, but i don't. I wasn't sure about what size of a clutch would be good, Thanks for the help. Any idea on the charging coil?

 

[landuse]

If i had the money to get a torque converter i would, but i don't. I wasn't sure about what size of a clutch would be good, Thanks for the help. Any idea on the charging coil?

Sorry, but I can't help with the coil

 

[anderkart]

If i had the money to get a torque converter i would, but i don't. I wasn't sure about what size of a clutch would be good,

Does your engine have a 3/4" diameter output shaft, or 1 inch? (is that hole in the center threaded?)
How tall are your back tires?
Will you be riding off road/climbing hills or just riding on flat hard ground?
Measure and post the distance between the tips of your axle sprocket teeth. (Is it 1/2"?)
Do you have a 60 tooth axle sprocket now?

Any idea on the charging coil?

What model number is your engine?

 

[TripleT]

It has a 1 inch and the hole is threaded, im not sure about back tires right now. Im going to be off road and on flat ground. I don't have a sprocket now. HM-80 155140

 

[TripleT]

Whats the benefit of a jack shaft?

 

[South Kart3377]

Whats the benefit of a jack shaft?

Gear reduction/jack shafts are your clutch's best friend. If you want to go faster modify your engine not your gearing. Oh, and if your engine is a tec, to yourself a favor and get a billet rod and wheel, I've seen some bad things from tec stock rods. You should get a 10 tooth clutch and 72 tooth sprocket.

 

[anderkart]

I'll post more about your clutch after you post your rear tire height.

I wasn't able to find any charging coils sold for the older style HM-80 engines with points and an internal magneto like yours. But you might be able to upgrade to the newer style HM-80 components, there's lots of info about those here: http://enginesandmagnets.com/id11.html