Gear Ratios?

[Speedy76]

I just bought my first go cart. It's a Hammarhead mudhead and it only tops out at 15 mph but I think it has the power to go much faster. It's got a 6.5hp motor on it. When I use the go kart speed calculator on the internet it's saying I should be able to hit 25 however I can only get it up to 15. It has a 30 series torque converter with a drive sprocket that's 10 teeth and an axel sprocket that's 60 teeth. The wheel and tire diameter is 14in. Im just confused as to why this calculator is so far off. I would like it to go 35mph so I'm trying to figure out what sprocket id have to replace and what size. Anyone have any suggestions?

 

[chancer]

Well before we work on Changing gears to see 35. Which is possible.
We need to figure out why it wont do the 25mph that it should
Probably a belt slipping or something else wrong with the Torque Converter.
https://www.youtube.com/watch?v=a3FCcLlR-sg

 

[Randy H]

Maybe not getting full throttle. I've seen guys try to use an auto type belt too. That don't work good.

 

[Speedy76]

I am sure I have the right belt, but I did just take a better look at the buttons on the rear clutch. They are very worn down and need replacing. I will replace those and hopefully I'll see an increase in speed. Just wondering, do you think if these were worn that it would decrease speed?

 

[chancer]

We have some sharp guys here on these TCs I am not one of them.
But if you get impatient, There is ton of info at You tube.

I think The buttons will decrease the speed. not sure.

 

[Whitetrashrocker]

Actually worn buttons would let the belt slip too far down the sheaves and start rubbing the rivits and prematurely wear the belt.

I don't think there's enough to notice a speed difference.

 

[Speedy76]

Well I noticed that because of the worn buttons, the rear pulley could not function properly and the belt was not able to move down the pulley as it's rpm increased. This would explain me only being able to reach 15mph because it was essentially lowering the gear ratio. Thanks for the responses everyone. Anyone have any recommendations on how I could achieve 35mph? I'm thinking the easiest way is to add a few teeth on the drive sprocket on the rear pulley for the torque converter. If anyone's got any ideas it would be very helpful. Thanks

 

[hardcorewill]

Pic ????

 

[chancer]

You are at 10 and 60 6:1 ratio. Adding teeth to the TC sprocket will help.
Try a 12 tooth. That will take you to 5:1.=30MPH
But first and easiest is your Governor still on the motor?
I assume it is cause you got 25MPH on the Calc, which means you used 3600 RPM.
Removing the Gov will get you between 5000 and 5500.
For example on your calcs 5200 RPM will get you 36MPH
add in the 12 tooth and you get 43MPH.

 

[steved]

He wouldn't have one of those TC limiting flyweight deals installed?

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[chancer]

Anything is possible. But I have only heard of them once, and when I told you it was the second reference.

 

[steved]

I did find that deal on one of the parts sites, and it's referenced on my Manco...figure it's something that's been around a while ?

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[Speedy76]

Thanks for the replies. I did not take the governor off... I'm thinking about it. if I do take the governor off, will I actually be able to reach 40 for a sustained period? If you keep it at full throttle for a while it will explode right? What's the point of taking off the governor if you can't go full throttle? I understand that you can go full throttle in bursts but my sustainable top speed will be unchanged. I'll be able to go 40 for what, 3 seconds? I guess I don't see enough benefit to forget about the possibility of blowing it up. My mind can be changed though if someone sees more benefit.

 

[steved]

The governer I was referring is part of the TC.

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[Jason1213]

Okay well I saw this thread and started looking through it and chancer said to get a 12 tooth sprocket but i looked it up and they only sell them for #35chain and mines a #40chain. Do they mix?

 

[chancer]

No Jason. They do not mix.
But here is a #40 12 tooth
https://www.thebigbearingstore.com/12-tooth-sprocket-for-40-roller-chain/

 

[OzFab]

The number on a chain indicates the pitch, the distance from the centre of one pin to the centre of the next;
#2X(X) = 1/4" (2/8")
#3X = 3/8",
#4X(X) = 1/2" (4/8") &
#5XX = 5/8"...

 

[Speedy76]

I read somewhere that a #40 and #41 sprocket will fit a #420 chain. Just bought a 12t sprocket #40 even tho I have a #420 chain. Hope it fits.

 

[bob58o]

I read somewhere that a #40 and #41 sprocket will fit a #420 chain. Just bought a 12t sprocket #40 even tho I have a #420 chain. Hope it fits.

I think a #41 may work better than #40, if you can't get a #420 sprocket.

But new chain is cheap.

41 and 420 are same except for roller diameter.
420 has a 0.3125" Roller Diameter, 41 has a 0.306" Roller diameter.
The 420 chain may sit a little higher around the sprocket because the slightly larger diameter rollers may not fit all the way down around the sprocket teeth.
This should be ok though.

40 and 420 are same except for roller width.
The 420 Roller Width is 1/4", the 40 Roller Width is 5/16"
The 420 chain may be tight around the 40 sprocket.
#420 chain wants a 0.227" sprocket thickness.
#41 chain wants a 0.227" sprocket thickness.
#40 chain wants a 0.284" sprocket thickness.

All three have 1/2" pitch.

I think some people use a hammer to make the chain fit, but this cannot be good.

#41 chain is pretty cheap. Available at Blaines farm and Fleet.
You need two sprockets. One is #40, what is the other?

 

[steved]

http://www.gokartsupply.com/mobile/chain.htm

I used the measurements from the table on this site to determine my chain...the link pin diameter is also specific to 420 chain.

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