There are a handful of folks here really well experienced with electric karts who'll chime in with good advice. First, a couple of things..............
Your link has a scooter twist grip for a throttle, but you intend to build a gokart, correct? Here's a link to a kit that has a pedal throttle and a wiring harness that your kit doesn't, and has slightly higher rpm rating for the same 33 amps.
Amazon.com: VEVOR 1800W 48V Electric Brushless, DC Motor Kit High Speed Brushless Motor, with 38A Speed Controller & Throttle Pedal & Wire Harness Set, for Electric Scooter Go Kart E-Bike : Toys & Games
The sprocket that comes on these electric motor kits is a T8F type sprocket (basically a bicycle chain size), for shafts that have 2 flat sides like these electric motors. Most karters will use #35 type chains, a 3/8" chain, for which there's a virtually unlimited number of sizes of axle sprockets. I don't even know where to buy axle sprockets for T8F chains. Here's a chart of 3/8" and 1/2" chains to give you an idea how that works .............
Chain for Go Kart, Mini Bike | GoKarts USA®.....................Here's a link where you choose different sprockets for those double-flats motor shafts, including for #35 chains..............
Electric Motor Sprocket #35 T8F 25H 11T 9T Tooth For Gokart Scooter Quad Buggy | eBay
See if you can figure out how to send messages to other forum members here (I don't know how, never tried), and message "Functional Artist" with specific questions. You can look around the "Go Kart Discussion" section here for a thread titled "Slingshot", that's him, has good educational info to read.
(lots of info you may be interested in)
