Electric Motorcycle Final Assembly Standard Operating Procedure

1.Pre-Start Preparation
Qualified assemblers, inspectors and maintenance staff must be on duty. Required documents include the BOM, process sheet, torque table and inspection forms. Equipment covers a differential-chain conveyor, pallets, calibrated torque tools, leak tester, vacuum bleeder, end-of-line tester and battery test cabinet. Materials are kitted in advance with QR codes and used in FIFO order.

2.Process Flow (15 stations that can be merged or split)
Station 1: Laser-mark the VIN on the frame; depth ≥ 0.2 mm and 100 % scan success.
 

Station 2: Press headset bearings at 20 ± 1 kN, fit upper fork crown and torque the nut to 25 N·m.
 

Station 3: Mount the front wheel and disc; ensure disc run-out ≤ 0.25 mm and torque the axle nut to 55 N·m.
 

Station 4: Route the main harness, secure clips and connect the meter until a clear click is heard.
 

Station 5: Insert the battery rail, lock the battery with ≥ 300 N force and perform three insertion-removal cycles without sticking.
 

Station 6: Fix the controller and DC-DC converter at 10 N·m; crimp the ground lug securely.
 

Station 7: Install the hub motor and rear wheel, set chain slack to 20 ± 2 mm and torque the axle nut to 60 N·m.
 

Station 8: Mount the master cylinder, vacuum-fill DOT 4 brake fluid at ≤ –0.08 MPa and adjust lever free play to 5–8 mm.
 

Station 9: Fit headlamp, tail lamp and turn signals; keep wiring at least 10 mm from moving parts and fasten with cable ties.
 

Station 10: Attach body panels, seat and top box; panel gaps must not exceed 1 mm and colors must align.
 

Station 11: Power on and run a self-check; confirm no BMS or controller fault codes.
 

Station 12: Calibrate the throttle from 0.8–4.2 V smoothly and verify all lights and horn.
 

Station 13: Conduct a five-minute rain test at 0.1 MPa; insulation must remain ≥ 100 MΩ.
 

Station 14: Perform a 100 m road test: top speed ≥ 45 km/h and dry-braking distance ≤ 7 m.
 

Station 15: Final inspection for scratches larger than 0.5 mm², apply QC PASS sticker and scan the unit off the line.

3.Quality Control
Critical torques are captured in real time; the line stops automatically if out of spec. Battery, motor and controller serial numbers are linked to the VIN for full traceability. RFID checks confirm correct brake-fluid type, and the conveyor will not release the pallet if the battery is not latched. Patrol inspections occur every two hours, plus first-piece, last-piece and five-piece sampling.

4.Safety & 5S
Operators must wear cut-resistant gloves and safety glasses; insulated gloves are required at high-voltage stations. Battery terminals must be capped to prevent shorts. At the end of each shift, waste is removed and pallets are repositioned for a 5S score of at least 90.

5.Common Defects & Corrective Actions
Disc-brake squeal: caused by excessive disc run-out—re-check front-wheel installation and maintain run-out ≤ 0.25 mm.
No power: caused by loose main harness—add a secondary push at Station 4.
Seat lock failure: caused by hook height deviation—use a checking fixture and spot-check every shift.