Hobbywing XeRun Justock G2.1 21.5T 2050KV RC Motor Black HW30408012

The Hobbywing XeRun Justock 3650 SD G2.1 21.5T is a fixed-timing sensored brushless motor designed for 1/10 and 1/12 scale RC stock and sport racing. With a 2050KV rating, two-pole rotor and non-adjustable timing, it delivers smooth, consistent power for drivers seeking precise throttle control and a dependable racing setup. Its aluminium housing, precision bearings and serviceable construction also make it suitable for compatible RC crawlers and recreational models.

Features

• Fixed Timing for Spec Racing: Non-adjustable motor timing provides a consistent configuration for racing classes that permit this motor.
• 21.5T Sensored Brushless Design: Combines a 21.5-turn winding with a 2050KV rating for controlled power delivery.
• Precision Hall Sensor: Built-in rotor position sensing supports smooth startup, linear throttle response and precise low-speed control.
• Two-Pole Rotor: Designed for efficient operation in compatible 1/10 and 1/12 scale RC applications.
• Durable Internal Construction: Heat-resistant magnet, double-insulated windings and precision bearings support reliable performance.
• Aluminium Motor Housing: Helps dissipate heat during operation while providing a durable motor case.
• Silicone O-Ring Seal: Seal between the end bell and stator helps transfer heat to the housing and protect the Hall sensor from dust.
• Serviceable Design: Removable end bell allows access for cleaning, inspection and replacement of serviceable components.
• Copper Solder Tabs: Three low-impedance terminals allow secure connection of ESC motor wires.
• 2S–3S LiPo Motor Rating: Supports suitable 2S or 3S LiPo setups when used with a compatible ESC and vehicle configuration.
• Hobbywing XR10 Justock Compatibility: Designed to pair with suitable XR10 Justock ESCs for zero-timing racing setups.
• Versatile RC Applications: Suitable for selected touring cars, F1 cars, buggies, short course trucks and rock crawlers where the motor specifications are appropriate.
• Stock Racing Focus: Designed around established stock motor specifications, with event eligibility dependent on current class rules.

Specifications

• Brand: Hobbywing
• Product Range: XeRun Justock
• Model: 3650 SD G2.1 21.5T
• Manufacturer Part Number: 30408012
• SKU: HW30408012
• Barcode: 6938994419246
• Product Type: Sensored Brushless RC Motor
• Colour: Black
• Motor Size: 3650 / 540-Class
• Recommended Vehicle Scale: 1/10 and 1/12
• Motor Type: Brushless
• Sensor Type: Sensored
• Motor Turns: 21.5T
• KV Rating: 2050KV
• Pole Count: 2
• Timing: Fixed, Non-Adjustable
• Supported Battery: 2S–3S LiPo with Compatible ESC
• Internal Resistance: 0.070 Ohm
• No-Load Current: 3.0A
• Maximum Output Power: 115W
• Current at Maximum Output Power: 35A
• Motor Diameter: 35.9mm
• Motor Length: 52.5mm
• Output Shaft Diameter: 3.17mm
• Output Shaft Extension: 15mm
• Weight: Approximately 175g
• Front Bearing: 9.525 x 3.175 x 3.967mm
• Rear Bearing: 9.525 x 3.175 x 3.967mm
• Motor Power Connections: Three Copper Solder Tabs
• Primary Applications: Compatible Stock and Sport Class RC Racing
• Additional Applications: Compatible RC Rock Crawlers and Recreational Vehicles

Includes

• 1 x Hobbywing XeRun Justock 3650 SD G2.1 21.5T Sensored Brushless Motor

FAQ

Is the Hobbywing Justock G2.1 21.5T motor suitable for stock racing? Yes. It is designed as a fixed-timing motor for stock and sport racing applications. However, approved motor lists, winding limits, rotor specifications and ESC timing rules vary between events. Check the current regulations for your racing class before entering.

What is the KV rating of the Justock G2.1 21.5T? The 21.5T version is rated at 2050KV. It is a two-pole sensored brushless motor with fixed timing.

Can this motor run on a 3S LiPo battery? Hobbywing rates the motor for 2S–3S LiPo operation. However, many stock racing classes specify 2S only, and the ESC must support the selected battery voltage. Check your ESC, gearing and competition rules before using 3S.

Which ESC works with the Justock G2.1 21.5T? The motor is designed to work with compatible sensored brushless ESCs, including suitable Hobbywing XR10 Justock models. For sensored operation, use the correct sensor connection and ensure the ESC supports the motor and battery configuration.

Is the motor timing adjustable? No. The Justock G2.1 has a fixed-timing design with a non-adjustable end bell. This is a key distinction from adjustable-timing brushless racing motors.

Can the 21.5T Justock motor be used in a rock crawler? Yes. Hobbywing identifies the 21.5T and 25.5T Justock G2.1 versions as suitable for compatible rock crawler applications. Check motor size, gear reduction, ESC compatibility and expected running loads before installation.

Important Notes

• This product is the standalone 21.5T motor, not an ESC and motor combo.
• Motor timing is fixed and cannot be adjusted through the end bell.
• Competition eligibility depends on the current regulations and approved equipment lists for the relevant event.
• Although the motor supports 2S–3S LiPo, the connected ESC and racing regulations may impose a lower voltage limit.
• Requires a compatible brushless ESC, suitable sensor connection and motor wiring.
• The 3.17mm output shaft requires a compatible pinion gear with the correct bore and gear pitch.
• Motor wires connect to copper solder tabs; ready-fitted bullet connectors are not guaranteed.
• Check motor temperature and gearing after installation, particularly when using higher battery voltage or heavier vehicles.
• Do not assume the motor is waterproof. Protect it from excessive water, dirt and contamination.
• ESC, battery, motor pinion, tools and RC vehicle are not included.