Most commuter electric motorcycles use a hub motor (the motor is inside the rear wheel) or a mid-drive motor (the motor sits in the frame and drives the wheel by chain or belt). The motor has three thick phase wires from the controller and a thin cable for the Hall sensors (small sensors that tell the controller where the magnets are) and often a temperature sensor. This page is an assessment and hand-off: what a rider can check safely, and what the workshop will do.
Safety
- Motor phase wires carry high voltage and large current. Do not unplug them, cut them or measure them with the bike powered. See Make an electric motorcycle safe to work on.
- A sharp burning smell from the motor or controller is a serious warning (Letrigo). Stop riding and switch off.
- Do not open a hub motor at home. Strong magnets can trap fingers and the parts are hard to refit.
You need (rider)
- A safe place, a stand, a phone to record the noise and the dash code.
Steps
What the rider can check:
- Note exactly what happens: judder at pull-away, noise, loss of power, wheel hard to turn, heat. Note any code: Read electric drive error codes.
- With the bike off and on its stand, spin the drive wheel by hand. Feel for rough spots, scraping or a wheel that is very hard to turn. See Check hub motor bearings and play.
- Check that the brake is not dragging: Check for brake drag. On a mid-drive, check the chain or belt: Check and adjust chain slack.
- Look (do not touch) at the motor cable where it leaves the axle: crushed, cut, rubbed through, or melted. Damage here is common after a fall or a loose axle.
- Hand the bike to the dealer or fleet workshop with your notes.
What the workshop will do:
- Read the full fault history with the manufacturer's tool.
- Isolate the HV system following the manufacturer's procedure.
- Inspect and test the phase connectors: Check motor phase connectors.
- Test the Hall sensors and their wiring: Check motor position (Hall) sensors.
- Measure the windings and insulation with rated equipment and compare with the manufacturer's values: Check high-voltage insulation. There is no universal phase resistance or test voltage.
- Check the bearings, axle and seals. If needed, replace bearings or the motor as a unit.
What to ask for
- The fault codes found and their meaning for your model.
- Whether the fault is in the motor, the cable, the connectors or the controller, and how they proved it.
- Whether water got into the motor.
Check your work
- Smooth pull-away, no noise, no code over a full test ride.
If it did not fix the problem
- Motor tests good: Diagnose a controller fault.
- Motor hot on climbs: Check cooling of the motor and controller.