Wheel to clutch ratio

[nickydlax]

Hey guys, I just want to make sure my clutch wont get too messed up
I'm planning on buying a 16hp 1inch diameter shaft (3600RPM (will be changing it too 4500-5000 if once I tinker with the governor))
I'm thinking I like the acceleration if I had 56t on the sprocket and 14t on the clutch.

Basically what I'm asking is, what size wheels should I get?

And if either big (18''?) or small (10''?) is safe for the clutch, then how will either extreme effect my top speed as well as my acceleration?

 

[landuse]

Hey guys, I just want to make sure my clutch wont get too messed up
I'm planning on buying a 16hp 1inch diameter shaft (3600RPM (will be changing it too 4500-5000 if once I tinker with the governor))
I'm thinking I like the acceleration if I had 56t on the sprocket and 14t on the clutch.

Basically what I'm asking is, what size wheels should I get?

And if either big (18''?) or small (10''?) is safe for the clutch, then how will either extreme effect my top speed as well as my acceleration?

First off, welcome to the forum.

If you use a 56T and a 14T clutch, you are going to be geared waaaaaaaaaaaaaaaaaaaaaaayyyy to high. You will have Kentuck Fried Clutch in 2 seconds and your kart won't even move an inch. Even if you had 10" tyres, that gear ratio would be too tall.

The magic number is around the region of 6:1. This can get slightly higher depending on certain factors, but you generally want to have 6:1 or more. With 18" tyres, I would suggest gearing at least 7:1 or lower. This means that you would have something like a 10T clutch and 70T axle sprocket (you get the idea on how to calculate gear ratio eg. 70/10 = 7:1).

If you find that your axle sprocket is too big for ground clearance, you are going to have to use a jackshaft.

The fact that you are using a 16HP engine means that you are going to buy a 1" bore clutch, and they run to more than $100, so I would choose gearing wisely. You don't want to have to buy another one.

Where are you going to be riding? If it is offroad, I would suggest getting a Comet series 40 Torque Converter. Centrifugal clutches are not the best for offroading.

 

[nickydlax]

Thanks!
okay so I dont know much about jackshifts :/
Also, most of this will be on pavement, but some off roading is necessary
The only clutch i know how to use/install is a centrifugal one, so how difficult would it be to use/install your suggested set up and what would be the advantages?
alright, so, what size wheels should i get? assuming i go between 6:1 and 7:1
Oh, whats the difference in top speed vs acceleration in those two ratios

 

[landuse]

A comet 40 series Torque converter will be reasonably easy to install. You need to buy the driver and the driven (they aren't really that cheap), and then fabricate a jackshaft. (To have a look at what jackshafts look like, just do a search on the forum and you will see lots of pics).

I would think that you will probably be safe with 14" wheels at a ratio of 7:1.

A low ratio is a higher number (eg. 8:1) You sacrifice top speed for acceleration.
A high ratio is a low number (eg. 4:1) You sacrifice acceleration for speed.

Have a look at these. They will give you some idea of what the setup will look like

http://www.diygokarts.com/vb/showthread.php?t=13086
http://www.diygokarts.com/vb/showthread.php?t=21683
http://www.diygokarts.com/vb/showthread.php?t=11142
http://www.diygokarts.com/vb/showthread.php?t=4074

 

[nickydlax]

Your a lot of help!
okay so 7:1 = 14'' wheels, got it
so, the higher the gear ratio, the more acceleration.
how do the wheels correspond?
bigger wheels = greater top speed?
but do they effect acceleration and hurt my clutch

 

[landuse]

Your a lot of help!
okay so 7:1 = 14'' wheels, got it
so, the higher the gear ratio, the more acceleration.
how do the wheels correspond?
bigger wheels = _____?

Larger wheels sort of act as if you are gearing higher. The larger the tyres, the more likely you are going to smoke your clutch.

I cannot guarantee a 7:1 will work with 14" tyres on your kart. There are other factors like weight of kart and driver. A 7:1 is a good starting point to see if it will work for you

The higher the ratio, the more likely you are to smoke your clutch as well. You need to find that balance that works for you

 

[nickydlax]

so maybe something like a 6.6:1? and do the tire size also have a direct relationship with top speed vs acceleration just like the gear ratio does?

 

[landuse]

I would not really go below 7 if you are going to be using a centrifugal clutch. I would use 7 as a starting point and gear lower if needed. Tyres do sort of influence speed like gear ratio does?

 

[nickydlax]

alrighty then thanks
how do tires relate to my top speed
how do tires relate to my acceleration

 

[OzFab]

so, the higher the gear ratio, the more acceleration.

No, a high ratio will give you more top speed:

High ratio = low numbers = good top speed & lousy acceleration
Low ratio = high numbers = good acceleration & low top speed

Larger tyres make a difference because the overall circumference is larger, therefore, will travel farther on a single revolution (I'm guessing you get that though). The trick is to find the balance between a good gear ratio, adequate power & good tyre size.

Punch some numbers into our speed calculator & see what you get; the higher the top speed, the worse the acceleration will be...