We do not have a sprocket for 8mm chain that fit the Dirt Quad's motor except for the original 25 tooth sprocket.
However we do have a 9 tooth sprocket that will fit the Dirt Quad motor that is for #410 (1/2" x 1/8") bicycle chain.
We can custom make a sprocket for either 8mm or #410 chain that fits onto the Razor Dirt Quad rear axle. The rear axle's sprocket hub has an F4 mounting pattern and just about any size sprocket for 8mm or #410 chain can be custom ordered with an F4 mounting pattern from this page:
A 36 tooth sprocket for 1/2" x 1/8" bicycle chain which along with the 9 tooth motor sprocket would provide the right gear ratio for a 4 MPH top speed.
Here are part numbers and links to these parts:
9 tooth sprocket for #410 (1/2" x 1/8") chain item # CTE-24364:
Hello, I am looking to do this conversion also. I am wanting to set this up to haul a fishing Kayak. The Kayak is 14ft long with a trolling motor set up. Fully rigged I am looking at roughly 160 lbs. I would also be doing the conversion mentioned above to increase the torque and reduce top speed. Do you think this setup would be capable of hauling a Kayak of this length and weight through the sand? Are you using the stock tires or did you change them out to a balloon style tire. Steering is going to be an issue if I move forward with this due to the length of my Kayak, not sure how to set that up yet. I did see a remote control conversion kit that seemed like it would work well but I have to do some more research on that idea. Any advice would be greatly appreciated.