HOBBYWING JUSTOCK G2.1 25.5T SENSORED MOTOR (FIXED TIMING) HW30408013

Overview

The Hobbywing XERUN Justock G2.1 25.5T sensored motor represents the pinnacle of spec racing excellence for 1/10th and 1/12th scale RC car enthusiasts across the UK. Following on from the success of the original Justock G2, this fixed timing motor has been refined to deliver controlled, predictable performance that makes it an ideal choice for both competitive racing and recreational driving. Whether you're competing in stock or sport class races, training for upcoming events, or exploring the world of RC cars for the first time, this brushless motor combines cutting-edge engineering with reliable, straightforward operation that serious racers and beginners alike have come to trust.

The 25.5T configuration strikes an excellent balance between raw power and control, making it particularly suited for rock crawling applications and off-road racing where modulated throttle response is essential. With its low 1600 KV rating and compatibility with 2-3S LiPo batteries, this motor delivers smooth, linear power delivery that translates directly to improved lap times and more predictable handling characteristics. The sensored design ensures that acceleration is immediate and responsive, whilst the fixed timing removes variables that could otherwise complicate tuning and setup during crucial competition moments.

Built to the exacting standards that Hobbywing is renowned for, the Justock G2.1 25.5T incorporates heat-resistant magnets, precision Japanese bearings, and double-insulated windings that guarantee outstanding durability and reliability. This is a motor designed not just for a single season of racing, but for years of reliable service whether you're running in organised competitions or enjoying weekend bashers on your local circuit.

Key Features

• Fixed Timing Design — The fixed timing eliminates timing adjustments and removes potential setup complications, making this motor perfectly suited for controlled racing classes and spec racing formats where consistency and rule compliance are paramount. This design philosophy allows you to focus entirely on driving technique and vehicle setup rather than motor tuning variables.
• Heat-Resistant Magnet and Aluminium Case — The combination of a heat-resistant magnet bonded to a purpose-designed aluminium case provides superior thermal management compared to older iron case designs. The aluminium case actively dissipates heat away from the motor's internal components, which extends service life and maintains consistent performance throughout extended racing sessions or practice runs on your RC track.
• Double Insulated Windings — The winding insulation is applied in two separate layers, providing enhanced electrical safety and protection against moisture ingress. This construction technique significantly improves the motor's resistance to humid British weather conditions and extends operational reliability in damp garage environments or wet track conditions.
• High Precision Japanese Bearings — Both the front and rear bearings (D9.525×D3.175×t3.967) are manufactured to exacting tolerances, ensuring smooth, consistent rotation with minimal friction losses. These premium bearings reduce power loss and contribute to the motor's renowned linear, predictable power delivery across the entire RPM range.
• Strong Structure Rotor — The rotor is engineered with internal reinforcement and optimised mass distribution, guaranteeing exceptional mechanical strength and longevity even under the demanding conditions of competitive racing. This robust construction prevents flex or imbalance that could otherwise introduce vibration or unreliable performance.
• Built-In Hall Sensor with Non-Adjustable End Bell — The integrated Hall effect sensor combined with a precision-matched end bell delivers smooth, predictable commutation throughout the entire power range. The non-adjustable design removes potential for incorrect sensor timing, ensuring consistent performance every time you power up your RC car.
• Silicon O-Ring Seal — A specially-fitted silicon O-ring seal between the end bell and stator serves dual purposes: it conducts internal heat outward to the motor case for improved thermal management, and simultaneously prevents dust and moisture from contaminating the sensitive Hall sensor assembly. This is particularly important for UK racers dealing with damp conditions and dusty track surfaces.
• Detachable Structure Design — The removable end bell allows straightforward access to internal components for routine cleaning, maintenance, and replacement of common wearing parts such as the rotor and sensor module. This rebuild capability significantly extends the motor's service life and means you can keep your competition equipment running at peak performance season after season.
• Copper Solder Tabs with Low Impedance — The motor features pre-soldered copper tabs with exceptionally low electrical impedance at the connection point where you solder the ESC wires. This design choice ensures minimal voltage drop and maximum power transfer from your battery pack to the motor, translating into measurably better acceleration and top-end performance compared to motors using inferior connection methods.
• Perfect XR10-Justock ESC Compatibility — This motor is specifically matched with the Hobbywing XR10-Justock ESC for zero timing spec racing, representing a factory-tuned pairing that maximises performance and reliability. The motor also maintains full compatibility with all other Hobbywing electronic speed controllers and those from other reputable brands, giving you flexibility in your RC car setup and upgrade path.
• IFMAR and ROAR Compliance — The motor design strictly adheres to the specifications and regulations set by both IFMAR (International Model Auto Racing) and ROAR (Remotely Operated Auto Racing), making it eligible for sanctioned competition racing across the UK and internationally. This compliance guarantees that your investment meets the standards demanded by serious racing organisations.

Technical Performance

The Hobbywing XERUN Justock G2.1 25.5T represents a carefully engineered solution for 1/10th and 1/12th scale on-road and off-road racing applications. The motor's 1600 KV rating paired with 2-3S LiPo battery compatibility delivers a peak no-load current draw of just 2.8 amps, indicating efficient power utilisation and reasonable heat generation during normal operation. The 540 motor size (35.9mm outer diameter, 52.5mm length) fits standard 1/10th and 1/12th chassis with a 3.17mm (0.125 inch) shaft diameter, making installation straightforward on touring cars, drifters, F1 models, mini cars, buggies, 2WD SCT trucks, and dedicated rock crawlers. Weighing just 173 grams (6.10 ounces), the motor maintains a lightweight profile whilst delivering the structural integrity demanded by competitive racing. The sensored brushless construction eliminates brush wear and delivers superior efficiency compared to brushed alternatives, whilst the Hall sensor provides commutation data that enables ESC features like drag brake and smooth low-speed crawling. The motor's precision engineering, combined with Japanese bearing quality and heat-dissipating aluminium construction, makes it equally at home in competitive spec racing, regular training runs, or rock crawling applications where controlled power and reliability are non-negotiable.

What's in the Box

• Hobbywing XERUN Justock G2.1 25.5T sensored brushless motor
• Pre-soldered 3.5mm low-impedance bullet connectors on motor wires
• Motor instruction manual and documentation

What You Need to Complete

• 2-3S LiPo battery pack (7.4V–11.1V)
• Compatible electronic speed controller (XR10-Justock ESC recommended, or other Hobbywing or third-party ESCs)
• Hall sensor signal cable (available in multiple lengths, sold separately)
• 1/10th or 1/12th scale RC car chassis compatible with 540 motor size
• LiPo battery charger and balancer

Frequently Asked Questions

• Is the Hobbywing Justock G2.1 25.5T suitable for beginners to RC racing? — Yes, absolutely. Whilst this motor is equally at home in competitive spec racing, Hobbywing specifically recommends the entire Justock range as an excellent choice for beginners and those seeking a reliable practice motor. The fixed timing removes the complexity of timing adjustments, the sensored design delivers predictable power delivery, and the low KV rating means the motor won't overpower a developing driver. Many UK RC shops recommend Justock motors as the first serious brushless motor upgrade for anyone learning racing technique.
• What battery does the Justock G2.1 25.5T need? — This motor is compatible with 2-3S LiPo batteries (7.4V minimum for 2S, 11.1V maximum for 3S configuration). The 1600 KV rating means a 2S battery will provide moderate power whilst a 3S battery delivers more aggressive acceleration. Most racers run 3S for competitive events, though 2S is perfectly adequate for training and practice. The manufacturer specifies a no-load current of 2.8 amps, indicating efficient operation and predictable heat generation.
• Can I use the Justock G2.1 25.5T with ESCs other than the XR10-Justock? — Yes, the motor is fully compatible with all Hobbywing electronic speed controllers including the XERUN range, and it also works reliably with ESCs from other reputable manufacturers. However, Hobbywing specifically matches this motor with the XR10-Justock ESC for optimised zero timing spec racing performance. If you're purchasing this motor for a new build, pairing it with the XR10-Justock ESC will give you the benefit of factory-matched calibration and tuning.
• What makes the Justock G2.1 different from the original Justock G2? — The G2.1 evolution introduces fixed timing (eliminating timing variable complexity), improved solder tabs on the motor leads for easier and more reliable ESC connection, enhanced heat management through the aluminium case design, and refined internal engineering based on years of real-world racing feedback. The G2.1 represents Hobbywing's response to competitive racing demands and delivers a more user-friendly, reliable product than the original.
• Is this motor sensored or sensorless? — This is a sensored motor with a built-in Hall sensor assembly. The sensor enables smooth commutation at all RPM levels, supports ESC features like drag brake, and is essential for low-speed crawling applications. The non-adjustable end bell guarantees that sensor timing is factory-set correctly, removing potential setup errors.
• How does the silicon O-ring seal benefit the motor? — The silicon O-ring serves two critical functions: it conducts internal heat outward to the aluminium case where it can dissipate into the air, improving thermal management during long racing sessions. Simultaneously, it creates a seal that prevents dust and moisture from entering the Hall sensor assembly. This design choice is particularly valuable for UK racers who frequently encounter damp conditions and dusty track surfaces.
• Can I rebuild and maintain the Justock G2.1 myself? — Yes, one of the key design features is the easily removable end bell, which allows straightforward access to the rotor, sensor module, and bearing assemblies. You can perform routine maintenance, clean internal components, and replace wearing parts without special tools or sending the motor away for service. This design philosophy significantly extends service life and keeps your competition equipment running reliably.
• What vehicles can use the Justock G2.1 25.5T? — Hobbywing specifically lists compatibility with 1/10th and 1/12th scale on-road vehicles (touring cars, drift cars, F1 models, and mini cars) and off-road vehicles (buggies, 2WD SCT trucks, and rock crawlers). The 25.5T configuration is particularly suited to rock crawling and applications where controlled, modulated power delivery is essential.

Why Buy from RC Model Shop?

RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the HOBBYWING JUSTOCK G2.1 25.5T SENSORED MOTOR (FIXED TIMING) HW30408013 today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.