I used the jet Kymco supplied me with. I took off the carburetor by disconnecting the air intake, engine intake, auto bystarter, and then the fuel line. I left the throttle on, as I had enough slack to work on it next to my moped. You can wrap the fuel line around the seat lock to stop from spilling fuel. Then simply take off the bottom plate and replace the main jet, it's quite simple. Just take your time.