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Scorpion HKIII-4025-890 (6mm) Brushless Motor, Kv=890

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SKU: HKIII-4025-890
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The Scorpion HKIII-4025 motors follow in the footsteps of the larger HKIII-4035 models which re-wrote the book on power for helicopter models. Replacing the earlier model HK-4025-890, the HKIII-4025-890 motor features a new patented rotor can that provides several benefits. First, it is thicker for more stability at higher speeds, and this also helps to retain more of the magnetic field for higher efficiency. Second, the outer surface of the rotor can features a new spiral rib pattern that increases surface area and helps to move air around the motor for increased cooling and lower operating temperatures.

In addition to the mechanical changes to these motors, changes in metalurgy in the stator assembly and rotor can have increased the overall efficiency. This allows the motor to handle higher currents while developing more torque and more power that will allow your helicopter to perform like never before.

Scorpion HKIII Series Brushless Motors are built from the best materials available, and are designed to provide both quality and performance at an affordable price. Scorpion starts with high quality aluminum alloy parts that are produced on the latest CNC milling machines. These parts are then gold Electro-plated to provide a beautiful, long-lasting finish. The stators are made with 0.2mm laminations to give maximum efficiency, and minimum Eddy current losses. The stators are epoxy coated to prevent shorts, and are wound with wire that is rated at 180 degrees C (356 F). The magnets used in Scorpion Motors are the highest temperature rating available, making a motor that is virtually impossible to burn up in normal use.

All Scorpion HKIII-4025 series motors come with 4mm male Bullet style connectors already attached, and include a hardware package that contains 3 matching female Bullet connectors for your speed controller with matching heat shrink tubing. For maximum strength, the Scorpion HKIII-4025 series motors feature an 8mm motor shaft that is ground down to a 6mm diameter at the output end to fit standard size pinion gears. Since the HKIII Series motors are primarily designed for Helicopter use, they do not include a prop adapter. If you intend on running a prop on this motor, you will need to purchase a prop adapter for a 6mm shaft.

Scorpion Motors are built to last, and are backed with a 2-Year warranty against defects in materials or workmanship. However, due to the high RPM of these motors, and the fact that we cannot control the installation and setup, the bearings are not covered by the 2-Year warranty, nor is any subsequent damage caused to the motor by a bearing failure. Bearings are a normal wear item, and as such, need to be maintained and changed periodically. For maximum life, make sure that a sufficient gap is left between the pinion and main gear during motor installation to avoid binding, and put a small drop of oil on each bearing every 5-6 flights. It is the responsibility of the pilot to ensure that the bearings are maintained properly.

The Scorpion Motor Bearing Lubrication Kit is now available for maintaining the bearings in your helicopter motor. To view this product, please check out the Bearing Lubrication Kit.

For the best overall combination of quality, performance, and value, use Scorpion Motors in your helicopter!


Scorpion HKIII-4025-890 Motor Specifications
 Stator Diameter  40.0 mm (1.575 in)
 Stator Thickness  25 mm (0.98 in)
 Number of Stator Slots  12
 Number of Magnet Poles  10
 Motor Wind  4-4 Turn Delta
 Motor Wire  24-Strand 0.29mm
 Motor Kv Value  890 RPM per Volt
 No Load Current (Io)  2.30 Amps @ 10 Volts
 Motor Resistance (Rm) per Phase  0.010 Ohms
 Maximum Continuous Current  95 Amps
 Max Continuous Power (8-cell Li-Po)  2700 Watts
 Motor Weight  354 grams (12.49 oz.)
 Outside Diameter  49.98 mm (1.97 in.)
 Shaft Diameter  5.98 mm (0.24 in.)
 Motor Body Length  51.8 mm (2.04 in.)
 Overall Shaft Length  83.7 mm (3.30 in.)
 Max LiPo Cell  8s
 Peak Current  110 Amps (5 seconds)
 Peak Continuous Power  3750 Watts (5 seconds)
 Motor Timing  5deg
 Drive Frequency  8kHz

Included in the box

1 x Scorpion HKIII-4025-890kv Motor
3 x Female Connectors
3 x Heat Shrink
4 x M3 Screws

Weight including packaging


View Scorpion HKIII-4025-890KV (6mm) Full Dimension