Kart for the kids, sprocket size?

[hope2bag]

Hello all, i did some seaching but i was not able to find out what im looking for, This is what i want to do, make the 2 seater gokart i have now and make it slow enough for the kids.


this is what i have 6.5hp, 12 tooth clutch, 80 tooth sprocket and a 145/70/6 tire, 35 chain.


what can i do to slow this thing down? I have tried just at a little above idel speed, where the clutch kicks in, the cart take off slow then builds to much speed.

thanks
for the help

Eddie

 

[Kenny_McCormic]

Build a jackshaft setup. engine)
.........................................(jack shaft)
.......................................................)axle/wheel
) = sprocket

You can change sprocket sizes on the jackshaft to change gearing.

http://www.diygokarts.com/speed-calculator.html according to this at 2200 rpm (clutch lockup) the cart goes 14mph, what are you aiming for?

You could also consider making a manual clutch with the jackshaft setup, make the engine to jackshaft connection clutch less using a belt and pulley setup, but use a loose belt. then attach the gas pedal to the belt tensioner and leave the engine at idle. Assuming both pulley are the same size, at 1000 rpm the cart would go 6 mph.

 

[hope2bag]

i think the 6 mph would be good, could i acheve that will the jacksahft setup? what size sprockets?

 

[Kenny_McCormic]

12 tooth on the jackshaft, 80 on the axle, 2 pulleys of the same size on the engine side of the jackshaft wit the belt cluth mentioned. Or (this is probably the better idea, less parts to buy) using the cent clutch you could have a 24 tooth on the engine side of the jackshaft and at 2200 engine RPMs you would be going 7mph. However, this is all assuming you have 14 inch tires and I think im decoding the tire number wrong.

 

[hope2bag]

yea just doulbe check tire size is 14" so looks like the parts i need if reading and drawing this out right is a jackshaft kit with 12 tooth sprocket and a 24 tooth sproket. use my 80 tooth sprocket on the wheel and the 12 tooth centrifiacal (spelling) clutch on the motor, that i currently have.

 

[hope2bag]

well i call around, and looks like they dont make a 24 tooth sprocket? any suggestions, the only one i could find was a 20 tooth.

 

[Kenny_McCormic]

a 20 tooth should keep it under 10

 

[Kenny_McCormic]

yea just doulbe check tire size is 14" so looks like the parts i need if reading and drawing this out right is a jackshaft kit with 12 tooth sprocket and a 24 tooth sproket. use my 80 tooth sprocket on the wheel and the 12 tooth centrifiacal (spelling) clutch on the motor, that i currently have.

Yea motor>clutch>20tooth>jackshaft>12 tooth(could put in a 10 to make it even slower/get higher engine RPMs for more climbing power)>80 tooth>wheel

 

[hope2bag]

i have been seaching but am not able to find a speed calculator using a jack shaft. how are you cal. speeds

thanks

 

[Kenny_McCormic]

Calculate jackshaft speed at X engine RPM and enter that as RPM. Clutch teeth becomes teeth on axle side of jackshaft.

 

[hope2bag]

ok im totaly lost now, im sure theres a big right up on this somewhere? am i doing this right?
jackshaft speed
Diameter in Inches 14

Engine RPM 3600

Teeth
on Axle 20
Teeth
on Clutch 12

MPH 90

final speed
Diameter in Inches 14

Engine RPM 90
Teeth
on Axle 80
Teeth
on Clutch 12

MPH 1

 

[Kenny_McCormic]

No MPH is not RPM, you need to calculate the jackshaft RPM on your own. and my numbers were based on 2200 engine rpm (clutch lockup).

clutch teeth/jack shaft sprocket teeth*engine RPM=jackshaft RPM