jfuqua
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Hello all i am new to this forum and am planning on a father son project after xmas we have a frame motor and 4 wheeler wheels and tires will keep yall updated. Thanks 
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jfuqua
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is thinking what gear ratio would be good for a 19 in rear tire hmmmm.
hmm ive had a go kart with approx 15in O.D rear wheels and a 72tooth sprocket on rear with a 6.5hp. Seems to do just fine for one person on board. You wont really be able to spin the rear wheels though. Torque-A verters are nice if you can afford the extra cost.
sideways
Unfinished projects king.
r97
Measure twice cut once
and where your riding, weight, and what type of tranny you have.
Is the the quad motor as well? Or an industrial engine? How old is your son and would you want to give him any speed limits? If so, you could gear down a centrifugal clutch, if you'd like to let him go a bit more, then a torque converter, a form of a CVT, is your better option with tires of that size.
jfuqua
New member
Its for my son he is 7 wieghs around 40 lbs. i have a kart frame but am planning on having big tires for ground clearance. Speed is not a factor right now or i could put a throttle stop on it. I have a 5.5 horse honda motor and am going with a live axle i do not have the funds for a torque o verter so sprocket and clutch. I did a few speed calculators and seems like 12 to 60 is a good way. I want him to be able to ride off road no pavment in sight lol.... Thanks for all of the help and maybe this will help yall. Thank you guys
jfuqua
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Also i have heard of a jackshaft what is this and why or do i even need one can i go from clutch to sprocket i found info on go kart speed calculator says 21 mph but how far before it gets there like i said its a 7 year old and he dont need speed but there is mud maybe 15 mph tops i can put on a throttle stop?
jfuqua
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sorry to keep going on but the motor is a honda 5.5 that was a pressure washer the motor runs great and has a 3/4" shaft with a 3/16 keyway
Well, did the calculator take into account the size of your tires? And, I think that 12:60 may still be too high for a cent. clutch to take. With larger tires, the clutches usually require a lower ratio say 10:80 or 8:1 ratio. A jack shaft is a way to reduce the ratio without putting on a sprocket that is the size of Alaska. Pretty much, it is a mini axle somewhere on the kart that has a sprocket on each end and is about a foot long. Hypothetically, if you wanted a 10:1 ratio, you could get a clutch with 10 teeth and a rear sprocket with 100, but thats just impractical. Or you could go with a jack shaft. There could be 10 on the clutch, 25 on the input of the jack shaft, 10 on the output of the jack shaft, and 40 on the rear axle. To calculate the final ratio you multiply the ratio of clutch to input with the output to axle ratio. The above situation would yield a ratio of 10:1 with no sprockets larger than, I'm assuming, 7".
jfuqua
New member
thanks redsox i will look into that because im not sure there will be any low end on this thing. only top end after 500 feet hahaha
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