SPM Brushless Outrunner Helicopter Motor, 4730 350Kv M-SPMX-1085

Overview

The Spektrum M-SPMX-1085 Brushless Outrunner Helicopter Motor is a high-performance, precision-engineered power unit specifically designed for 800-class electric helicopters and advanced RC rotorcraft builds. This 4730 350Kv brushless outrunner motor represents the pinnacle of Spektrum's motor technology, delivering the torque, stability and refined control that serious helicopter pilots demand. Whether you're operating a Blade Fusion 800 platform or another large-scale electric heli, this motor is engineered to support demanding flight styles—from smooth, scale-realistic hover to aggressive 3D aerobatics and high-speed transitions.

The 350Kv rating is specifically chosen for pilots flying 6S to 12S LiPo battery configurations, ensuring that you get optimal RPM and torque delivery across a wide power envelope. This is not a beginner's motor; it is a serious component for experienced RC helicopter enthusiasts who understand voltage systems, rotor dynamics and the performance characteristics needed to get the absolute best from their aircraft. The low-Kv design means your large rotor blades will turn at the right speed to generate stable lift and responsive cyclic control, making this motor ideal for UK RC helicopter fliers who demand precision and reliability in competitive or recreational settings.

Built to Spektrum's renowned standards, this brushless motor combines proven outrunner architecture with durable construction to withstand the vibration, torque stress and thermal demands of modern 800-class helicopter flying. Every component is engineered for extended flight sessions without heat buildup or performance degradation. When you choose the M-SPMX-1085, you're investing in a motor that will deliver consistent, predictable performance flight after flight, making it the trusted choice for UK RC helicopter pilots and hobby builders who refuse to compromise on quality or power delivery.

Key Features

• 350Kv Low-Kv Rating — The 350Kv specification is precisely calibrated for large rotor blades on 800-class helicopters, delivering the low-RPM torque necessary to drive high-inertia rotors efficiently. This means you get stable lift characteristics and responsive cyclic control across the entire throttle range, whether hovering with scale realism or executing demanding 3D maneuvers.
• 4730 Outrunner Size Class — The 4730 frame size is engineered specifically for torque-hungry applications where large-diameter rotor systems demand sustained power delivery. This size class balances rotational inertia with thermal management, ensuring the motor can handle extended flight sessions without temperature spiking or performance loss.
• Brushless Architecture — Brushless design eliminates carbon brush friction and wear, resulting in cooler running temperatures, higher efficiency and extended operational lifespan. This is especially critical for helicopter applications where sustained throttle inputs and dynamic load changes demand a motor that won't overheat or lose responsiveness during intensive flights.
• Outrunner Configuration — The outrunner design places the rotor bell on the motor's outer case, which naturally enhances torque at lower RPMs compared to inrunner alternatives. This configuration delivers the precise cyclic control and torque characteristics that helicopter pilots need for smooth hovering and responsive pitch and roll inputs during advanced flight maneuvers.
• 6S–12S LiPo Compatibility — This motor is engineered to safely handle voltage configurations ranging from 6S to 12S LiPo batteries, giving you flexibility to match the motor to your preferred power system and aircraft frame. Whether you're running 6S for efficiency or 12S for maximum RPM headroom, the motor will deliver predictable, stable performance across the entire voltage window.
• Preinstalled High-Current Connectors — The motor ships with secure, high-current bullet terminals already installed, eliminating the need for soldering and reducing setup time. This means you can integrate the motor into your helicopter frame quickly and safely, with connectors rated for the sustained current draw typical of large-scale electric helicopter systems.
• OEM-Compatible Sizing — The motor dimensions and mounting interface are designed to fit directly into Blade Fusion 800 platforms and other compatible 800-class helicopter frames, enabling seamless integration without custom fabrication or adapter plates. This compatibility saves time and ensures optimal fitment and performance from day one.
• Robust Build Quality — Every component is engineered to withstand the vibration, thermal stress and sustained torque demands of competitive and recreational helicopter flying. The motor's construction is reinforced to handle the cyclic loading that occurs during rapid cyclic input changes and aggressive 3D maneuvers.

Technical Performance

The Spektrum M-SPMX-1085 delivers performance metrics specifically optimised for 800-class electric helicopters. With a 350Kv rating and 4730 frame size, this outrunner motor is engineered to work seamlessly with 6S to 12S LiPo battery systems, ensuring that pilots have flexibility in power system selection whilst maintaining predictable torque and RPM characteristics. The brushless architecture minimises heat generation and electrical noise, critical for helicopter systems where thermal stability directly impacts flight duration and motor longevity. The outrunner configuration naturally biases the motor's torque curve toward lower RPMs, which is essential when driving large-diameter rotor blades on 800-class machines where rotor blade pitch and collective control demand responsive, linear throttle response. The motor's construction integrates precision-machined components and robust bearing systems designed to handle sustained high-current draws without vibration or runaway behaviour. Pilot feedback consistently demonstrates that this motor delivers the smooth RPM control and torque linearity necessary for precise hovering, scale-realistic flight profiles and aggressive 3D aerobatics. The thermal management of the brushless design ensures that extended flight sessions don't result in temperature spiking or performance degradation, allowing pilots to conduct back-to-back flights without waiting for the motor to cool down. Whether used in competitive helicopter racing environments or recreational scale rotorcraft flying, the M-SPMX-1085 proves itself a dependable, high-performance powerplant that grows with pilot skill and evolving flight demands.

What's in the Box

• Spektrum M-SPMX-1085 Brushless Outrunner Helicopter Motor (4730 350Kv)
• Preinstalled high-current 6mm bullet connectors

What You Need to Complete

• Brushless ESC (Electronic Speed Controller) rated for your battery voltage and desired current capacity
• 6S–12S LiPo battery pack compatible with your helicopter frame and power requirements
• Helicopter frame and rotor head assembly (e.g. Blade Fusion 800 or compatible platform)
• Motor mounting brackets and hardware appropriate to your airframe
• Radio receiver and flight control system if not already installed in your helicopter
• Charging system for your LiPo batteries
• Propeller/rotor blades matched to the 800-class helicopter design

Frequently Asked Questions

• Is the Spektrum M-SPMX-1085 suitable for 800-class helicopter beginners? — This motor is engineered for experienced RC helicopter pilots who understand voltage systems, ESC programming, rotor dynamics and advanced flight techniques. The 350Kv rating and 4730 size class require knowledge of power system configuration and tuning. Beginners should start with smaller, less demanding helicopter systems before progressing to 800-class machines powered by this motor.
• What battery voltage and configuration does this motor require? — The M-SPMX-1085 is designed for 6S to 12S LiPo battery configurations. This means you can power it with anything from a 6-cell (22.2V nominal) through to a 12-cell (44.4V nominal) LiPo pack, depending on your ESC rating and desired RPM characteristics. Lower voltage (6S–8S) will prioritise torque and flight duration, whilst higher voltage (10S–12S) will increase maximum RPM for faster rotor speeds and increased aerobatic capability.
• What is the difference between the 350Kv M-SPMX-1085 and other Spektrum helicopter motors? — The 350Kv rating makes this motor ideal for large-diameter rotor systems typical of 800-class helicopters. Spektrum also manufactures higher-Kv motors (such as the 540Kv 4735 variant and 3400Kv Revolution 235 CP) designed for smaller helicopter classes or different power delivery profiles. The 350Kv rating specifically targets pilots flying 800-class rotorcraft who need torquey, responsive power delivery at lower RPMs. The 4730 frame size is matched to this Kv rating for optimal thermal balance and performance characteristics.
• Do I need a specific ESC for this motor? — Yes, you will need a brushless ESC rated for your intended battery voltage (6S–12S) and capable of handling the sustained current draw of an 800-class helicopter system. Your ESC must be programmed to work with brushless motors and should support modern helicopter flight control systems. Consult the ESC manufacturer's specifications and your helicopter's documentation to ensure compatibility and proper programming before first flight.
• How does the 350Kv rating improve helicopter performance? — The 350Kv specification means the motor will turn approximately 350 RPM per volt of battery voltage applied. On a 6S pack (22.2V), you'll see roughly 7,700 RPM; on 12S (44.4V), you'll see approximately 15,400 RPM. This low-to-mid Kv range is optimised for large rotor blades, ensuring they turn at precisely the right speed to generate smooth, controllable lift without requiring extreme blade pitch angles or sacrificing flight stability.
• Is the Spektrum M-SPMX-1085 compatible with Blade Fusion 800 helicopters? — Yes, the motor is OEM-compatible with Blade Fusion 800 platforms. The frame size, mounting interface and electrical specifications are designed to integrate directly into these airframes, eliminating the need for custom adapters or fabrication. This compatibility ensures optimal fitment and performance from the moment you install the motor.
• What makes brushless motors better than brushed alternatives for helicopters? — Brushless motors eliminate carbon brush friction, resulting in significantly cooler operation, higher efficiency and dramatically extended motor lifespan. For helicopter applications, where sustained throttle inputs and dynamic load changes occur constantly, the cooler running temperature of brushless designs is critical for preventing thermal shutdown and maintaining consistent performance throughout extended flight sessions. Brushless motors also generate less electromagnetic noise and vibration, improving overall aircraft stability and radio system performance.

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 SPM Brushless Outrunner Helicopter Motor, 4730 350Kv M-SPMX-1085 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.

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