1975 Honda Monkey Z50J 75cc Bored Engine Overhaul Complete

1975 Honda Monkey Z50J, frame number Z50J-1168, engine number Z50JE-1159. Odometer reads 3,681 km. One repair key controls main switch, handlebar lock, and helmet holder. All electrical systems functional. Tank interior coated by previous owner. Side cover has cracks with visible previous repair.

Complete engine overhaul performed: new NTN bearings (crank, main shaft, countershaft), all oil seals and gaskets replaced, new clutch discs, valve lapping and stem seals replaced. Kitaco 75cc big bore kit, Kitaco high-cam shaft, Kitaco reinforced oil pump with enlarged orifice. Kitaco intake manifold and throttle set. New 19mm big carburetor (OEM Keihin PC20 replacement, disassembled and serviced). Compression verified, ignition timing adjusted, charging confirmed.

Frame: new steering stem bearings, front fork spring re-greased, new front and rear tires and tubes, new front and rear hub bearings and oil seals, new brake shoes serviced, new drive chain and sprockets (14T front, 28T rear). All shafts and swing arm re-greased, brake and meter cables oiled. Converted to 12V system with new bulbs, battery, flasher relay, and regulator. New fuel petcock.

All replacement parts are new. Vehicle is 50+ years old with overall rust and scratches; no repainting or cosmetic repair performed. Set for flat torque and street rideability rather than power. Good starting, stable idle, can maintain highway traffic flow. Engine run-in in progress; further carburetor tuning likely needed. Suitable for owners comfortable with vintage motorcycle maintenance. Stored indoors, no rain riding or pressure washing. Video link provided. Current location Tokyo, Mitaka Ward. In-person inspection welcome.

50+ years old with overall rust and scratches throughout the body. Side cover has cracks with previous repair; no cosmetic restoration performed. Engine just built and in run-in phase.