FAQ
What is the Kunray KR5V motor used for?
The Kunray KR5V is a 72V 5000W brushless electric motor designed for high-performance electric vehicles, including electric dirt bikes, electric motorcycles, go-karts, and performance upgrades for compatible Razor vehicles.
Is the Kunray KR5V suitable for electric dirt bikes?
Yes. The Kunray KR5V electric dirt bike motor is built for demanding riding conditions, offering strong acceleration, stable output, and reliable performance for off-road and high-load applications.
What makes the Kunray KR5V a high torque motor?
The Kunray KR5V is a high torque motor with strong low-RPM output, allowing faster starts, improved hill-climbing ability, and better control under heavy load compared to lower-power motors.
Is the Kunray KR5V a brushless electric motor?
Yes. The Kunray KR5V is a brushless electric motor (BLDC), which provides higher efficiency, reduced maintenance, lower heat generation, and a longer service life compared to brushed motors.
Can the Kunray KR5V be used as a Razor motor upgrade?
Yes. The Kunray KR5V is commonly used as a Razor motor upgrade for models such as Razor MX, SX, and RSF series, offering significantly more power and torque than stock motors when properly installed.
What voltage and power does the Kunray KR5V motor require?
The Kunray KR5V is designed to operate at 72V with a rated output of 5000W, delivering strong and consistent power when paired with a compatible controller and battery system.
What controller is recommended for the Kunray KR5V motor?
For optimal performance, Kunray recommends using a high-current brushless motor controller compatible with 72V systems. Proper controller matching ensures smooth acceleration and protects the motor during high-load operation.
Is the Kunray KR5V motor suitable for daily riding or only performance use?
The Kunray KR5V is suitable for both daily riding and performance applications, provided the vehicle setup, cooling, and electrical system are correctly configured for 72V operation.
Does the Kunray KR5V motor require special maintenance?
As a brushless electric motor, the Kunray KR5V requires minimal maintenance. Regular checks of wiring, mounting hardware, and cooling conditions are recommended for long-term reliability.
Is the Kunray KR5V motor beginner-friendly for installation?
Installation is straightforward for users with basic electric vehicle or DIY experience. For first-time installers or high-power builds, Kunray recommends professional installation to ensure safety and proper performance tuning.
Specifications
| Specification | Value |
|---|
| Rated speed | 6000 rpm |
| Peak speed | 8000 rpm |
| Rated torque | 8.5 N·m |
| Peak torque | 35 N·m |
| Load weight | About 100–200 kg |
| Pole count | 5 pairs (10 poles) |
| Drive sprocket | #35 9T, #35 11T or 420-10T |
Construction Highlights
- Reinforced V2 case, shaft and sprocket mount. The housing and shaft were revised and the sprocket now sits on a larger diameter, so the drive end takes repeated chain load with less flex. Brand codes are engraved into the case, which makes identification and after-sales support straightforward.
- Interior permanent magnet rotor. The IPM layout keeps output steady when current is high, so the motor holds its pull on long climbs instead of fading as it warms up.
- Full copper coil in an aluminium body. As a brushless DC electric motor it has no brushes or commutator to wear out, and the copper windings and aluminium housing move heat away from the rotor without any coolant to top up.
- Phase leads sized for the current. The 8 mm² phase wire gives your controller a clean path for the current these builds draw, keeping voltage drop and heat at the connectors to a minimum.
Machine Fitment
| Machine or build | How it fits |
| Razor MX650 | Direct mount, no chassis modification |
| Razor MX500 | Direct mount, no chassis modification |
| Razor SX500 | Direct mount, no chassis modification |
| Razor RSF650 | Direct mount, no chassis modification |
| Razor Indian650 | Direct mount, no chassis modification |
| Electric dirt bike | Mid-drive conversion on a dirt bike frame |
| Go-kart | Mid-drive conversion, #35 or 420 drive sprocket |
| Mini e-motorcycle | Mid-drive conversion on a 72V build |
| ATV | Mid-drive conversion for heavier loads |
Controller Compatibility
Rotor position comes from a Hall sensor, so pair the motor with a brushless motor controller that reads Hall input rather than a sensorless-only unit. That is what gives clean, quiet starts from a standstill instead of a hesitant launch. Kelly and Fardriver units are both supported, and our own testing runs a 60–100A controller — the NS18-KR72V100A is a common pairing. Reverse is not built into the motor: it is switched on inside the Fardriver app, which is also where current and speed limits are set. If your controller is rated well below what the motor draws under acceleration, it will cut out rather than let the motor reach full output.
Heat Limits & Care
- Stay under 65 °C. 150 °F (65 °C) is the working ceiling — past that the magnets and windings are at risk, so set a temperature-based power cut-off in your controller rather than judging it by feel.
- Keep the case breathing. The housing releases heat into the air around it, so clear packed mud, dust and debris from the cooling surfaces after wet or dusty rides.
- Off-road use only. This electric dirt bike motor is intended for off-road riding, so check your local rules before using it on public roads or paths.
- Post-ride checks. Every few rides, look at the mounting bolts, chain tension and the wiring connections — a loose connection is the usual cause of rough running on high-current builds.
Technical Support & Model Matching
Not sure which motor suits your build? Our team helps you match a brushless motor or complete kit to your voltage, wattage, sprocket type and controller, so the parts work together from the first ride. We can advise on sine-wave controller pairings for Hall motors, sprocket and chain compatibility, and temperature-sensor options for builds that run hot. Need a base-mounted version or a different power rating? Just ask. We also guide installation, wiring and basic fault-finding once your order arrives.
