The motor is the single most critical component in the Razor MX125 and SX125's drivetrain. It is the factory-specification 12-volt, 100-watt chain-driven motor — the MY6812B-12 — that converts battery power into the rear-wheel drive that propels both bikes, delivering the high-torque, chain-driven performance that gives the MX125 and SX125 their authentic motocross character in a scaled-down, child-friendly package.
When the motor fails — whether through prolonged use, water ingress, bearing wear, or an electrical fault in the windings — the symptoms are immediate and unmistakable: the bike refuses to move, moves only weakly with no acceleration, or cuts out under load. In every case, replacing the motor with the correct genuine part is the definitive repair.
This is the genuine factory replacement motor for the Razor MX125 Dirt Rocket and SX125 McGrath, rated at 12 volts and 100 watts, with a 7-tooth #25 chain sprocket pre-fitted to the output shaft. It is a direct, bolt-in replacement for the original motor, using the same mounting configuration, the same shaft diameter, and the same sprocket specification as the unit it replaces — ensuring that the bike's chain alignment, gear ratio, and rear-wheel drive performance are restored exactly as designed
Genuine 12V / 100W Factory Specification — Rated to the exact 100-watt output of the original motor, ensuring the bike delivers the same acceleration, top speed, and torque as it did when new. Aftermarket motors with lower power ratings produce noticeably weaker performance; those with incorrect voltage ratings can damage the speed controller and wiring harness.
7-Tooth #25 Sprocket Pre-Fitted — The motor arrives with the correct 7-tooth #25 chain sprocket already installed on the output shaft, matching the factory gear ratio and chain specification of the MX125 and SX125 drivetrain. No additional sprocket sourcing or fitting is required — the motor is ready to install straight out of the box.
Direct Bolt-In Replacement — The MY6812B-12 motor uses the same mounting hole pattern, shaft diameter, and connector configuration as the original. Disconnect the old motor, bolt in the new one, reconnect the chain and wiring, and the repair is complete.
High-Torque Chain Drive Restored — The chain-driven rear-wheel drive system is what gives the MX125 and SX125 their authentic dirt bike feel. Replacing the motor with the genuine part restores the full high-torque, chain-driven performance that makes both bikes so engaging for younger riders.
Resolves the Most Serious Drivetrain Failure — A failed motor renders the bike completely inoperable regardless of the condition of the battery, controller, or chain. Replacing the motor with the genuine part restores full drivetrain function in a single repair
Razor MX125 Dirt Rocket
All versions
Razor SX125 McGrath
All versions
Voltage check — essential before ordering: This is a 12V motor. It is designed exclusively for the MX125 and SX125, which run on a 12V battery system. It is not compatible with Razor products that use 24V or 36V motors — including the Crazy Cart, E100 Glow, E200, or Crazy Cart XL — all of which use different motor specifications and mounting configurations. How to identify your version: Locate the barcode sticker on your battery cover or the bottom of the frame. The 7th and 8th digits of the product ID code indicate your version number (e.g., ""01"" = Version 1)
