Help with sprockets

[Grand Dad]

I am working on a Manco kart I bought for my grandkids. The original sprockets were made of stamped steel and did not last one summer. The kart came with a 10 tooth clutch to a 36 tooth on a jack shaft with a 12 tooth on the shaft to a 36 tooth on the axle. I removed the jack shaft and sprockets.I bought a 10 tooth max torque clutch and a 48 tooth for the axle. The new items are for #40 chain. The kart will not move. The clutch slips gets very hot quick.
The kart has a curb weight of 224# and 145/70 tires. My yard is not to rough and I think 15-20 mph would be ok.I am new to karting and would like to get it going for them.Thanks

 

[Affair_driven]

What is diameter of tires?

 

[Jerryburger]

If I did my calculations right, you went from a 10.8>1 ratio to a 4.8>1 ratio. (If you ditched the jackshaft.) I'm guessing your Manco is like mine- with the detachable sprocket (on a hub with 6 bolts?).... try to order a 72 tooth sprocket from manco, or a dealer. My kart came stock with one, and it got around fine with a 5hp and two people in it. It maxed out at 23 mph @ 3600 rpm. My tires are similar sized to yours.

 

[Grand Dad]

Thanks for the quick replies. I will measure the tires today. I did remove the jack shaft it was junk both mid sprockets were made together. I will order a 72t sprocket and give it a try.
I not plan to put the jack shaft back in. I understand the ratio with two sprockets but how do you figure with a jack shaft with two more sprockets. I must have been sleeping that day at school.

 

[Kaptain Krunch]

To figure out two ratios just multiply

3:1x3:1=9:1

 

[Grand Dad]

Thanks for the info Kaptian! My tire diameter is 13.5 inches. Where can I find a 72t sprocket for #40 chain? Or should I revert back to #35? I changed to #40 because #35 was stretching. I changed to #40 clutch,sprocket and chain. Will #35 carry the load? Open to all suggestions.....

 

[Affair_driven]

I agree with Mr. Jerry. 72 tooth is good.
One thing though...chain does not actually stretch.
Can be minimized by frequently cleaning and re-lubing with a chain specific lubricant. Many on the market. Most work equally well.
Plain oil or grease is bad news for obvious reasons.

 

[Jerryburger]

I'd stick with #40/41 chain. (Personal preference). My favorite place to check for stuff 1st is Ebay. (Just checked- no luck.)
Found this link that carries a 60t for the manco. (8th picture down)
http://www.gokartsupply.com/sprocket.htm


This sprocket would give you 24 mph @ 3600 rpm. What hp motor are you running?

 

[Grand Dad]

Thanks Jerry and Affiar. I am running a 5hp Robin that came with the kart. Is there an ideal ratio for the sprockets?

 

[Jerryburger]

The 5hp should pull the 60t okay. Those Robin motors are nice.

 

[alexdegnall]

i have a home made go kart with a 10 clutch and a 60 sprocket the chains to big and slips off and i cant cut it because it wont fit and im wondering if a smaller sprocket would make it go slower or faster or the same and if the smaller sprocket would work what size shud i get

 

[Grand Dad]

Are you sure the sprockets are for #40 chain? Make sure the sprockets are aligned.

 

[mike75925]

hey guys chains do stretch, this is usually what eats the sprockets . run em in then when you are maxed on adjustment you should be able to remove one inner and outer link ( 1 total link) this is very common on motorcycles. known as break in period i think.

 

[Grand Dad]

Success...

Thanks for the help guys! I got a 60t sprocket and installed it Friday. Everything works good. 10t clutch with 60t driven sprocket with #40 chain. My grand son is very pleased. Thanks again.