ElectricScooterParts.com Support Center

You are welcome. If you need one we have chain breaker tools available on our Tools Page. For #420 chain I recommend our item # CHB-4253 chain breaker because it is the easiest one to use that works with #420 chain. 

                         CHB-4253

The chain length is measured as one long chain layed out flat, and not as it would be when it is connected into a circle.

I just added a few longer lengths of chain to the kit in case more chain is needed. 

If you tried to order the kit and could not because the shopping cart said that the battery charger was out of stock I have that fixed now so the kit can be ordered.

Please let us know if you have any questions or if you would like any changes made to the kit.

Here are top speed gear ratio calculations with the 72-tooth 11.752" OD sprocket that is currently installed on the cart and with a 60-tooth 9.840" OD axle sprocket and 48-tooth 7.928" OD axle sprocket.

The top speed does not increase very much when changing the axle sprocket to a smaller size and a change to 48 tooth sprocket only increases the top speed by 1.75 MPH. 

The faster the top speed is the lower the torque at the wheels will be so installing a smaller axle sprocket will decrease hill climbing speed and ability. 5.27 MPH is still a very low speed for a 650 Watt motor though so it will have a lot of torque. 

It is hard to say what will work best without knowing the exact weight of the load and cart and the percent of incline that the cart will need to go up. I ran a calculation for a 300-pound cart and load going up a 25% incline with a top speed gearing for 5.27 MPH and found that the 650 Watt motor will handle it with a top speed decrease to 2.63 MPH. It will go up steeper hills or carry heavier loads with more of a decrease in top speed and less steep hills or lighter loads at faster uphill speeds. These uphill calculation are based on hard packed dirt or pavement and deep sand is likely to slow the cart down more than estimated by the calculations. 

I just checked and the 10 tooth sprocket is the smallest size made for the 24 Volt 650 Watt gear motor. 

Power and payload capacity are dependent on the amount of torque at the drive wheels. When changing to a smaller axle sprocket the amount of torque will be reduced in relation to the decrease in sprocket size. For example, the amount of torque with a 3.52 MPH top speed will be reduced 25% with a 5.27 MPH top speed. So switching from a 72 tooth axle sprocket to a 48 tooth axle sprocket will reduce the torque by 25%, and switching from a 72 tooth axle sprocket to a 60 tooth axle sprocket will reduce the torque by 12.5%. 

One way to get around the problem of having too large of an axle sprocket without changing the top speed is to install a jackshaft, then an axle sprocket with around half the number of teeth could be installed and the top speed would remain the same. We carry a weld-on jackshaft kit for #420 chain with 8 tooth and 17 tooth sprockets which would lower the gear ratio by 53% so then a 36 tooth axle sprocket with a 6.015" outside diameter could be used and the top speed would be 3.31 MPH. A jackshaft setup like this would slightly increase the torque and power/payload capacity over using the 72 tooth sprocket without a jackshaft. 

Our jackshaft kit for #420 chain with 8 and 17 tooth sprockets is item # JST-581420817 and our 36 tooth axle sprocket is item # SPR-420361. Both of these parts are available on our #420 sprockets page.

We can get axle sprockets for #420 chain in just about any size so if you want a different size axle sprocket such as 32 tooth or 40 tooth just let us know how many teeth you need and we add that size to our site. 

Going from a 72 to 57 tooth axle sprocket would reduce the torque at the wheels by around 13.5%.