The Dirt Quad's stock chain has 74 links. If a 36 tooth sprocket is installed then a 68 link chain will be needed.
Here are chain size calculations for the original 47 tooth sprocket and a 36 tooth sprocket.
We sell the item # SPR-836F 36 tooth sprocket for 8mm chain on this page: https://www.electricscooterparts.com/sprockets8mmchain.html
We sell item # CHN-800 8mm chain sold by the link and item # CHN-8ML 8mm chain master links on this page: https://www.electricscooterparts.com/chain8mm.html
Please let us know if you have any questions.
Awesome, the Dirt Quad looks plenty fast now. That's a nice park that you have to ride it in. Thanks for sharing the videos.