More Powerful Sur-Ron Motor: What you gain by replacing it and what you need to consider

Replacing the motor in a Sur-Ron Light Bee with a more powerful motor primarily allows you to sustain high power output for longer periods without overheating, and to utilize a more capable controller. However, a motor alone cannot achieve this: it's the controller that sends the current to it, and the battery that provides the power. Before changing the motor, it's crucial to understand what you want to achieve and to prepare the rest of the system. Here's what you gain, and what you need to consider afterward.

Why does the original motor become a limiting factor?

An electric motor often accepts more current than its original controller sends to it; that's why the controller is often the first part to be replaced. However, more current means more heat in the windings, since losses increase with the square of the current. An overheated motor loses torque, and its magnets can degrade permanently. On a long uphill climb, during off-road riding, or on a track, the original motor, when pushed hard, quickly reaches its thermal limits. Our guide on electric motor overheating explains this phenomenon.

What you gain with a more powerful motor:

• Torque: A motor designed for high current output provides more force to the wheel, especially during startup and acceleration.
• Consistency: It maintains power for a longer duration before its thermal protections reduce it.
• Headroom: It can handle the settings of a more powerful controller without operating at its limit.

Our RM30 motor for Sur-Ron Light Bee was designed for this purpose. Advertised at 30 kW, it is an interior permanent magnet (IPM) motor, which allows for MTPA (Maximum Torque Per Ampere) activation on compatible controllers; it spins up to 12,000 RPM, can withstand temperatures up to 180 °C, and has been thoroughly tested for months, starting in April 2023. It comes with a pulley for the original belt, and is available in four colors. You can find it in our Sur-Ron Light Bee motors category.

MTPA (Maximum Torque Per Ampere) and internal magnets

In an interior permanent magnet (IPM) motor, the magnets are housed within the rotor instead of being glued to its surface. This design creates, in addition to the torque generated by the magnets, a torque known as reluctance torque. A controller that manages MTPA ("maximum torque per ampere") directs the current to take advantage of both: more torque for the same current, which means less heat for the same amount of power. Our guide on IPM and SPM motors explains this in detail.

Here's what you need to follow:

The controller

The controller must read the motor's sensors. The RM30 is equipped with Hall sensors, making it compatible with most controllers. After installation, the controller needs to learn the characteristics of the new motor, which is the detection phase, and then be configured: currents, throttle response, motor brake, temperature limits. Our guide on choosing a controller for a lightweight electric motorcycle provides the selection criteria. Our motorcycle controllers are available with RageLink, and are currently on a waiting list.

The battery

More power means more current drawn from the battery. If the battery's BMS (Battery Management System) or its cells cannot handle the increased current, it may cut power during acceleration or degrade rapidly. The motor, controller, and battery must be chosen together as a compatible system.

The drivetrain, the brakes, and the tires

The additional torque is transmitted through the primary belt, the chain, and the sprockets: check their tension and wear more frequently. The brakes must dissipate more energy, and the rear tire will wear out faster. These points are detailed in our guide for preparing a Sur-Ron Light Bee.

Initial test rides

Increase the power in increments, while carefully monitoring the motor and controller temperatures, any potential cutouts, and braking performance. This is where you can see which component reaches its limit first.