Frame design

Millwright

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A little more progress.
Not sure what's up with the colour. It was supposed to be gloss white.
 

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Millwright

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A little more assembly.
Still need to work out brakes and throttle.
Have a couple issues with TC to sort out.
 

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Millwright

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Well my belt has finally arrived.
Throttle linkage and brakes still need to be completed, and then I'm good to go!!
I have an assortment of sprockets to play around with.
10, 13, 18, 36, 45, 54, and 60.

Kart weight with me should be about 425 lbs.
Wheel size is 16"
Engine is box stock 420cc
40 series torque converter.

I'm looking for reasonable torque to get going, but more interested in top end speed.

I'm guessing the 13,T with the 54T might be my best combination.
 

madprofessor

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That's a 4.15:1 final ratio with the 54:13, but be sure. If you find you need more low end torque, you may find you need a larger axle sprocket than there is available reasonable ground clearance for it.
Starting with a 10T on the CVT will allow you to use smaller sprockets on the axle, and that can be as small as you dare go to load top end.
Conversely you could fit a real torquey larger axle sprocket without chewing it into the sand. Think wood baseball bat into a meat grinder.
 

Millwright

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That's a 4.15:1 final ratio with the 54:13, but be sure. If you find you need more low end torque, you may find you need a larger axle sprocket than there is available reasonable ground clearance for it.
Starting with a 10T on the CVT will allow you to use smaller sprockets on the axle, and that can be as small as you dare go to load top end.
Conversely you could fit a real torquey larger axle sprocket without chewing it into the sand. Think wood baseball bat into a meat grinder.
Well I'm thinking I'm going to have enough HP to always reach the 3600 RPM, so I'm guessing I might get into using the 18T on the driver.
Anyways, that's why I picked up a range of sprockets. I'll play around with the ratios, see how high, and how low I can go and still have a functional kart. I'll be running on a flat paved rural road so I'm not too worried about the rear sprocket grinding in the sand.
I'm pretty certain I'm going to start of with the 6:1 ratio, and then increase the tooth count on the drive hub.
 

madprofessor

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I'm a cheapskate and sometimes lazy. I'd go the other way, starting with the biggest sprocket I might want to use and shrinking down from there.
Why? Because each sprocket change downward would mean removing a chain link(s) instead of having to add little bits to the chain.
No extra master links and half links to buy to make up the chain.
And on that rigid kart I'd most definitely make a rigid idler gear chain tensioner and lock it down. Spring-loaded ones are for suspensions.
Pic attached of chain drive to pitman arm with a spring-loaded tensioner made into a rigid one, using the cheap nylon roller that was on it. Other pic is secondary drive chain with an idler gear that gets adjusted up/down for tension and then locked down.
 

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