Hi all! I was wondering how many teeth I should get when I buy a gear. Right now I have a 10T 41P clutch and a #41 roller chain; I'm a noob at building go-karts (this will be my first) and I don't know how many teeth I should have on my gear. I'd like to to have a high top speed. I'd like to use it on and off road.
Gearing question
- Thread starter Maus
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OzFab
Well-known member
We need more information:
- What type of kart is it
- What size rear tyres
- What type of drive do you have (cvt or centrifugal clutch)
- What engine do you have
- What type of kart is it
- What size rear tyres
- What type of drive do you have (cvt or centrifugal clutch)
- What engine do you have
Its a one seater kart (that all I can really tell you). It has a 11 inch diameter, currently is 3 inches off the ground (I'm going to buy bigger tires). Its a centrifical clutch. And the engine is a 6.5Predator 212cc that my brother built for race, he says it will go up to around 6500 rpms. I'd like for it to go about 40 mph.
Tyre size is very important when it comes to gearing, so you are going to have to figure out what your final diameter is going to be so that we can give you the correct information. Getting larger diameter tyres is like gearing higher, and you can potentially fry your clutch
If you are going to stay with the smaller tyres you have now, I would suggest a 60T sprocket. If you are going to go with larger tyres, you are going to have to go larger than 60T. This might cause ground clearance issues, so you might then need a jackshaft.
If you are going to stay with the smaller tyres you have now, I would suggest a 60T sprocket. If you are going to go with larger tyres, you are going to have to go larger than 60T. This might cause ground clearance issues, so you might then need a jackshaft.
No problem. We will need the height of the tyre from the ground to the top of the tyre. This includes the rim in the middle. Have a look at the pic I have uploaded. I know it is not a kart tyre, but you get the idea
Right now I'm just going to use the wheels I got now, they are 11" tall and my current sprocket is 7" tall, if that helps any. I was playing with the speed calculator and found that a 53t would give me the speed I wanted. Would a 53 teeth sprocket give me pretty good acceleration?
OzFab
Well-known member
Hmm, maybe. It will give you a final drive ratio of 5.3:1 which is a bit on the high side but, not too much. If the engine has extra torque, you'll probably be ok...
60T would be better
So with 60T i'd get 6:1? To my understanding, the more teeth the more acceleration and the the less teeth the more power/speed? Also, on my frame there is a broken weld and i'm not sure if I need to weld it back on or if I should soder (that spelt right?) back on or even consider trying to sodering it.
OzFab
Well-known member
Not quite: Power = RPM x torque so, leave that out & you're spot on:
High ratio number = low gear ratio = good acceleration but low top speed
Low ratio number = high gear ratio = poor acceleration but high top speed
In some cases, it depends on what it is but, to be safe, I'd weld it. Solder is akin to glue &, under the right conditions, will act like a glue & separate; welding is a permanent bond
So the 5.3:1 will give me speed, and the 6:1 will give me acceleration? I also have to factor in the wieght of the frame with the engine on it, about 85lb and my self, around 150-160, on it to get the most accurate speed. So with either of the sprocket i'd be flying, probable my so with the 60T. 
OzFab
Well-known member
6:1 is a reasonable trade-off between the two. 5.3:1 will give you a slightly higher top speed but acceleration may suffer; 7:1 will give you great acceleration but a not so good top speed.
Again, with a race prepped engine, I'm confident you should be ok @ 5.3:1
Again, with a race prepped engine, I'm confident you should be ok @ 5.3:1
Again thank you both very much!- Status