1986–1991 Yamaha Jog 50, CE50, CG50 Scooter Service & Repair Manual (P/N LIT-11616-05-43)

• Covers Yamaha CE50S (model code 1UV) from VIN JYA1UV00GA673101 / engine 14T-673101, CE50T (2HE) from VIN JYA2HE00HA700101 / engine 14T-700101, and CG50U (2VK) from VIN JYA2VKA0*JA000101 / engine 2VK-000101.
• 282-page PDF combining the CE50S factory service manual P/N LIT-11616-05-43 (1st edition, September 1985), CE50T supplementary manual P/N LIT-11616-05-79 (September 1986), and CG50U supplementary manual P/N LIT-11616-06-34 (November 1987).
• Covers the 49 cm³ air-cooled two-stroke single-cylinder engine, Yamaha Autolube system, dry centrifugal automatic clutch, V-belt transmission, electric starter, and kick starter.
• Includes exploded diagrams, factory torque and maintenance specifications, electrical troubleshooting charts, cable-routing references, and model-specific CE50S, CE50T, and CG50U wiring diagrams.

Model-Specific Coverage

Yamaha structured these publications in layers rather than repeating the full base manual for each later version. The CE50T supplement introduces changed service data for that model, while the CG50U supplement states that it is to be used together with both the CE50S manual and CE50T supplement. Because all three publications are included in this PDF, a CG50U owner has the earlier base repair procedures as well as the later model-specific changes in one reference.

The CE50T material concentrates on revised handlebar-cover work, steering adjustment, front fork and steering service, specifications, cable routing, and the CE50T wiring diagram. The CG50U supplement adds its own body-cover procedures, engine-oil and Autolube service information, signal-system troubleshooting, revised electrical specifications, cable routing, circuit diagrams, and CG50U wiring diagram. This distinction matters when choosing repair values or identifying parts, since the later CG50U is not simply a relabeled CE50S.

Engine, Transmission, Chassis, and Electrical Repair

The base manual goes well beyond routine maintenance. Factory procedures cover engine removal, cylinder head and cylinder service, piston and piston-ring inspection, primary and secondary sheaves, starter system, C.D.I. magneto, Autolube pump, transmission, crankcase separation, crankshaft inspection and installation, and complete engine reassembly. The carburetion chapter documents the Y12P Teikei Kikaki carburetor, electric auto-choke with P.T.C. thermistor and wax element, carburetor section view, auto-choke unit testing, and reed-valve inspection.

Chassis repair coverage includes front and rear wheel removal, brake-shoe plate service, drum and lining inspection, front fork and steering overhaul, steering bearing adjustment, and rear shock absorber inspection. Electrical fault finding is organized by system, with troubleshooting charts and component checks for the electric starter, ignition, charging, lighting, signal, and auto-choke circuits. Representative technical illustrations include the Auto Choke System wiring schematic, Carburetor section view, CE50S Electrical Starting System circuit diagram, Ignition System circuit diagram, plus the CE50T and CG50U wiring diagrams.

Factory-level procedures that commonly push an owner toward a repair shop are covered by name and specification: compression testing, Autolube pump cable adjustment and air bleeding, engine removal and internal overhaul, crankcase separation and crankshaft installation, clutch and secondary-sheave service, carburetor disassembly and auto-choke testing, steering-race/front-fork service, starter-motor checks, and ignition/charging fault tracing. Special-tool references include the Compression Gauge YU-33223, Flywheel Magneto Puller YM-01189, Clutch Spring Holder YS-28891, Crankcase Separating Tool YU-01135, Crankshaft Installation Set YU-90050, and Pocket Tester YU-03112.

Factory Specifications and Variant Differences

The manual keeps CE50S/CE50T and CG50U specifications separate. CE50S and CE50T use a 7.2:1 compression ratio, 2.9 L fuel tank, 2.75-10 tires, BP6HS-10 spark plug, 1,500-2,100 r/min idle range, and 2,300-2,700 r/min clutch-in speed. Their clutch-stall range is 3,700-4,300 r/min.

CG50U data changes several of those benchmarks: 6.7:1 compression ratio, 3.5 L fuel tank, 3.00-10 tires, BP7HS spark plug with 0.6-0.7 mm gap, 38/10 (3.800) secondary reduction, carburetor I.D. 2YR00 with a #90 main jet, 1,800 r/min idle speed, 3,150-3,650 r/min clutch-in speed, and 4,650-5,350 r/min clutch-stall speed. The CG50U Autolube pump stroke is specified at 0.34-0.55 mm.

Common repair benchmarks include a 40.1 mm cylinder-bore wear limit, 0.034-0.047 mm piston clearance, 15.0 mm V-belt width with a 13.5 mm wear limit, and 4.0 mm clutch-shoe thickness with a 2.5 mm wear limit. Cylinder-head fasteners are specified at 10 Nm (7.2 ft-lb), and transmission oil capacity is 0.10 L for a periodic change or 0.11 L total. The CE50S compression test gives 784 kPa (114 psi) as standard and 628 kPa (91 psi) as the minimum at sea level.

Several manual-specific cautions are important during repair. Yamaha warns against spinning cleaned bearings with compressed air because it can damage the bearing surfaces. During crankcase separation, the case must not be forced or struck on the gasket mating surface, where damage can compromise the case and sealing face. The CE50T steering instructions also warn that an unevenly installed bearing race can damage the frame or steering column.

Always remember that technical data provided here serves solely for general reference before starting a project. Mechanics and owners must consult the complete OEM literature before attempting physical maintenance or parts replacement to ensure personal safety and vehicle integrity.