hey guys I am new to this forum and to the karting world. I just bought a good running Streaker. The tires that were on looked like they have been in a burn out contest. so I took it to a local tire shop and put some bigger turf type tire on it. now it still runs great but there is not that much power on take off and it will not even come close to spinning the tires (like what i saw from the old tires). can some one tell me what I did by changing the tire size to a 2 inch bigger tire. specs are 5hp briggs engine with a 10t clutch and a 72t drive sproket.
do tire size change the gear ratio
- Thread starter mark28138
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to the forum!! Getting larger tyres on your kart is like gearing higher. You are going to sacrifice torque for a bit more speed. If you want to burn rubber again you are going to have to gear a bit lower (lower than 7.2:1 that you have), or go back to the smaller size tyres that you had.
Using a 13T clutch will mean that you are gearing even higher than what you are now. This is just going to make your problem worse. A 13T clutch and 72T sprocket is going to give you a ratio of 5.5:1, which is too high really for a kart even with smallish tyres.
You are going to want to gear lower (a higher gear ratio number). That means either a lower tooth count on the clutch or a higher tooth count on the axle sprocket. A 72T is pretty big, and you might not be able to get bigger without ground clearance issues. A 10T is pretty much the smallest you can get. You are therefor between a rock and a hard place. To rectify the problem you can do one of 3 things. Firstly, use a jackshaft to allow for smaller sprockets. Secondly, get smaller tyres again, and thirdly, get a torque converter
You are going to want to gear lower (a higher gear ratio number). That means either a lower tooth count on the clutch or a higher tooth count on the axle sprocket. A 72T is pretty big, and you might not be able to get bigger without ground clearance issues. A 10T is pretty much the smallest you can get. You are therefor between a rock and a hard place. To rectify the problem you can do one of 3 things. Firstly, use a jackshaft to allow for smaller sprockets. Secondly, get smaller tyres again, and thirdly, get a torque converter
No problem
chris_the_poser
Member
He could also get bigger rear sprocket sacrificing ground clearance of course but jackshaft would be best bet then he could play with different gear ratios to see what he likes best
realfast89gt
Kart Krazy!!
Or, add some power to that engine to help compensate........
devino246
Official DIYGK Chem Nerd
Tire size doesn't affect the gearing, it affects the amount of force transfered from the axle to the ground. Bigger tires = less force, more speed. Smaller tires = more force, less speed.
No. Centrifugal clutches can only handle so much. If a 5hp isn't moving the kart adequately, a larger engine won't either. The clutch is the limiting factor.
No. Centrifugal clutches can only handle so much. If a 5hp isn't moving the kart adequately, a larger engine won't either. The clutch is the limiting factor.
realfast89gt
Kart Krazy!!
Good point. My brother went through the same thing with his kart that had a clutch setup. Kept changing gear ratios and adding power but the clutch still wanted to slip....hmmm wonder why....
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