Sprocket change? Need advice.

[Cooper1972]

I fixed up a kart for my rugrats recently. Put new tires all around, front has 6" rims with 14.5" tires behind are 7" rims with 16" tires. Engine is a Honda GX160, centrifugal clutch (torque converter) has 10 teeth and sprocket is 60 teeth, uses a #41 chain. The kart has a high top end speed with little low end power. I would like to have more low end power and I am not concerned about top end speed. I was looking at changing to a 72 tooth sprocket. How much difference will this make? I would greatly appreciate any advice regarding this issue. I have lots of hilly country for my kids to ride this on. Looking to make it a good dirt kart. Sorry for the upside down pictures. I'll try to fix them and repost. EDIT got the pictures fixed!


Thanks

 

[ghostdog]

Going to a 72 tooth would help greatly. That's about the best thing you could do.

 

[souperman000]

thats just a plain cent. clutch, not a torque converter

 

[landuse]

Using a 72 tooth sprocket will give you a gear ratio of 72/10 = 7.2:1. While this is a lot better than 6:1 (which you have at the moment), you have to factor in that you have now put on larger diameter tyres, and that you want to use it in hilly country.

I cannot tell from the pics, but you must also check that the diameter of the 72T sprocket is not so large that it will scrape on the ground, or snag anything that you ride over. If this is the case, you are going to have to use a jackshaft to get compound gear reduction, or use a torque converter. If your kart is one wheel drive, a TC is however not ideal.

All that being said, you are going to have to change the sprocket anyway, so I would do it and see if it works out for you.

 

[souperman000]

hey where do you live? If you want to get rid of the tires, I might be able to buy them off you.

EDIT - Never mind I am stupid. I misread the post. sorry

 

[anderkart]

I'd suggest swapping out to an 80 tooth.

Your estimated top speed with a
60-tooth is 29mph,
72-tooth is 24mph
80-tooth is 21mph


If your sprocket bolts on with four-5/16"-bolts, and has a 4" bolt-circle pattern, you could buy an 80-tooth #41 sprocket here: http://www.gokartgalaxy.com/uni-hubs_&_vari-hubs.htm Its 1/4 of the way down that page under the heading: Heavy Duty Sprockets for Heavy Duty Sprocket Holder

This link shows the diameter of #40/41 sprockets: http://www.azusaeng.com/Sprockets/AzSDno40.pdf
That 80-tooth has a diameter of 13.026", so that means you'd end up with a little less than 1-1/2" of clearance between your sprocket/chain and the ground.

Do you know about torque converters and jackshafts? If you installed one of these you could get even more gear reduction and keep using your current 60-tooth sprocket.

 

[Cooper1972]

Thanks to everyone for the advice. I now have a new set of questions that need answers.

I think my cent. clutch has given up. After my children put it through a rather abusive session the other day it quit working, started making funny noises and little bits of metal dust were puffing out of all the holes. This setup uses a #41 chain. Seems like all parts used with this size chain are considerably more expensive than #35 chain. Would I be going wrong in changing to #35 chain, sprocket and clutch, or are #41 chain and components superior to # 35. Again, thanks for all your help with these issues.

 

[anderkart]

I think you'll be fine with #35 as long as you use a high quality chain.
I use and recommend this one: http://shop.stoudtskartsandparts.com/product_p/rlv102.htm

 

[jman231994]

#41 is a bigger chain than #35 and is therefore, assuming similar metal quality etc, superior for most applications. But as anderkart said, get good quality #35 and you shouldnt have any issues

 

[Cooper1972]

I took the clutch off and cleaned it up some and it is working well now. I am not sure what was wrong with it before but it is working fine now. I am going to stick with the #41 chain since the clutch works. I still plan on changing the sprocket to enhance the low end power and slow this thing down a little. I am 6'3" and 255lbs and I had this little cart going 29.2mph on my GPS. It's a fun little cart to ride.