35HP Kart Build

[JTSpeedDemon]

I believe the technical term is an A-arm for that kind of suspension setup, but I'm not 100% sure, and it doesn't really matter anyways. Can't wait to see the first drive!

 

[Budget GoKart]

My yerfdog is almost done just need to tune it and buy a new slide for the carb

 

[Stephen115]

I believe the technical term is an A-arm for that kind of suspension setup, but I'm not 100% sure, and it doesn't really matter anyways. Can't wait to see the first drive!

Yes, you are correct. The replacement ones from BMI karting are of better quality. I may have to do the other side next.

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---------- Post added at 04:34 PM ---------- Previous post was at 04:33 PM ----------

My yerfdog is almost done just need to tune it and buy a new slide for the carb

Awesome! I'm experiencing some carb issues myself. Once warmed up the engine starts backfiring out the exhaust... may need to adjust the float bowl.

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[Stephen115]

Wish I had a video of me riding the kart for you guys, but the clutch isnt working correctly.

The centrifugal clutch doesn't grab under load, but does grab when not under a load. Load meaning on the ground.

We're 99% there. I have another clutch to try, I just need to find it.

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[rushking19]

Wish I had a video of me riding the kart for you guys, but the clutch isnt working correctly.

The centrifugal clutch doesn't grab under load, but does grab when not under a load. Load meaning on the ground.

We're 99% there. I have another clutch to try, I just need to find it.

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You might need to get a cvt set up

 

[JTSpeedDemon]

What's your gearing like? That engine has a ton of power but it must weigh something ridiculous.

 

[Budget GoKart]

Im currently drooling i need this engine on my yerfdog lol

 

[Stephen115]

You might need to get a cvt set up

Do they make a CVT that will handle 40hp?

---------- Post added at 12:35 PM ---------- Previous post was at 12:33 PM ----------

What's your gearing like? That engine has a ton of power but it must weigh something ridiculous.

I'll have to wait till I get home and check. It has pretty high gearing due to the clutch sprocket and limited space for the drive sprocket.

The engine weighs around 150lbs, the kart itself is actually pretty light.

 

[JTSpeedDemon]

You may need a jackshaft setup. Or if you wanted to pay a lot, you could invest in a 780 series torque converter. https://www.gopowersports.com/gopowersports-780-tav-kit-18-to-30hp/

It's $600eek, but it's rated for 30 HP, and Carsandcameras' used one on their 60HP drag rail with no problems.
It sounds like a classic gearing issue though.

 

[Stephen115]

You may need a jackshaft setup. Or if you wanted to pay a lot, you could invest in a 780 series torque converter. https://www.gopowersports.com/gopowersports-780-tav-kit-18-to-30hp/

It's $600eek, but it's rated for 30 HP, and Carsandcameras' used one on their 60HP drag rail with no problems.
It sounds like a classic gearing issue though.

That's probably what I have in this so far haha.

Have any information on gear ratios or a calculator that can help me determine what I need?

 

[Stephen115]

The clutch is a 20 tooth and the sprocket is a 53 tooth. I remember we had to use a 53 tooth for clearance, but I make a bigger sprocket work.

53/20 = 2.65:1 .... back to the drawing board. Do you think a 72 or 74 tooth would be better? Inputs welcome. Rear tires are 18'' tall.

 

[JTSpeedDemon]

20T clutch??
Try finding a smaller clutch. The PTO shaft is 1" diameter, right?

The DIYGK homepage has a good gear ratio speed calculator, or you could try http://kartcalc.net/
With that kind of gearing, go as big as you can with the axle sprocket, so 74 tooth, and that's mostly to start.

---------- Post added at 08:18 PM ---------- Previous post was at 08:14 PM ----------

Here's a 10T clutch, it's about $80. https://www.gopowersports.com/10t-1-bore-centrifugal-clutch-41/
Only rated up to 7 HP, but centrifugal clutches are bulletproof compared to torque converters(a LOT more moving parts. By halving the clutch tooth count, that should at least get it driving, and an upgrade to a 70-something tooth axle sprocket should get you boogyin'!

 

[Stephen115]

20T clutch??

Try finding a smaller clutch. The PTO shaft is 1" diameter, right?



The DIYGK homepage has a good gear ratio speed calculator, or you could try http://kartcalc.net/

With that kind of gearing, go as big as you can with the axle sprocket, so 74 tooth, and that's mostly to start.



---------- Post added at 08:18 PM ---------- Previous post was at 08:14 PM ----------



Here's a 10T clutch, it's about $80. https://www.gopowersports.com/10t-1-bore-centrifugal-clutch-41/

Only rated up to 7 HP, but centrifugal clutches are bulletproof compared to torque converters(a LOT more moving parts. By halving the clutch tooth count, that should at least get it driving, and an upgrade to a 70-something tooth axle sprocket should get you boogyin'!

Yeah, it's a 1 1/8" shaft. I struggled to find a clutch until one of the members here had one.

I'm going to order a couple different sizes and see what happens. I used the calculator and it says a 74 tooth will give us a top speed of 54 mph versus 74 with the current setup. No wonder it's not going anywhere.



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