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I have built a go kart with a 3000rpm 36v motor  with the motor sprocket being 11 tooth and axle being 44 tooth.The kart loaded weighs about 250 lbs. With the batteries fully charged the kart barely moves on flat ground, no movement on slight incline, but takes off down hill . On flat ground with a push it takes off better. Motor seems to be bogging down . Could this be the sprocket size? I was thinking about trying a 72 tooth.What do you suggest my next step be? Thank you in advance, Todd

That could be caused by the sprocket size creating too high of a gear ratio. We can run some calculations to help determine what the right sprocket size should be. To do this we will need to know what the diameter of the rear wheel is?

Rear wheel diameter is 16" . All parts are new.

With 16" wheels and a 44 tooth axle sprocket, the gear ratio is for a 35.82 MPH top speed which is too high for a 1000 Watt motor.

A better gear ratio would provide a top speed of around 25 MPH if the go-kart will be used on flat ground only, or of around 20 MPH if the go-kart will be used to go up gentle hills, or of around 15 MPH or lower if it will be used to go up moderate hills. 

A 72 tooth axle sprocket will change the gear ratio to a 21.87 MPH top speed as shown in the calculation below.

We also carry a 10 tooth motor sprocket that would reduce the gear ratio by another 10% and get the top speed down to 19.9 MPH with a 72 tooth axle sprocket.

The lower the gear ratio is the better the go-kart's hill climbing ability will be.

We do not know how steep the hills are or how much the go-kart weights, so these gear ratio recommendations are estimates only and the final determination for the correct gear ratio will need to be made after the gear ratio has been changed and the go-kart is tested under the conditions that it will be used in. 

I will order both . I will keep you updated .Thank you

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