The ID tag shown in your attached photo indicates that the bike is a version 11.
We have a variable speed kit for the Razor MX350 version 9-32 which is our item # RAZ-EKIT8.
For everyone who has a Razor MX350 version 33+, we have a variable speed kit for it which is our item # RAZ-EKIT10.
Both of these kits include a new throttle and a new controller which are required for the upgrade.
These kits are available on our Razor MX350 Dirt Rocket Electric Dirt Bike parts page.
You are welcome.