1998–2000 Yamaha CW50 Factory Service Manual

• Engine overhaul covers removal, crankcase separation, crankshaft installation, and cylinder, piston, and ring inspection.
• V-belt transmission service covers the dry centrifugal clutch, primary and secondary drives, reduction gears, and kick-starter repair.
• Separate DELL'ORTO and TEIKEI carburetor sections cover disassembly and reassembly, with fuel-valve testing and inlet-valve inspection.
• Front disc and rear drum brake maintenance extends to caliper and master-cylinder repair, hydraulic bleeding, and brake-shoe replacement.
• Front fork teardown, seal replacement, and reassembly are covered alongside steering-head bearing inspection and adjustment.
• Electrical troubleshooting addresses no-spark, no-crank, charging, lighting, and signal-system faults, supported by wiring diagrams and switch-continuity charts.

Manual Coverage

This 219-page PDF contains the 182-page CW50 '98 Workshop Manual (4VV-AE1) and the 37-page CW50 '00 Supplementary Service Manual (4VV-AE2). Both page counts include covers and wiring sheets.

Written by MBK INDUSTRIE for Yamaha/MBK dealers and qualified mechanics, the base manual outlines the complete teardown, inspection, and reassembly of the air-cooled, single-cylinder two-stroke engine. It also covers routine inspection, adjustment, and chassis service.

The 2000 electrical supplement is not a standalone engine-and-chassis overhaul manual. Its foreword specifies the CW50 ('99) Service Manual, 4VV-ME1, as the companion reference; the base manual included in this PDF is the '98 edition.

Autolube, Fuel Delivery & Engine Repair

The lubrication section covers Yamaha Autolube pump removal and installation, feed-hose and drive-gear inspection, and oil-system bleeding. Transmission service reaches the internal shafts, bearings, and seals, rather than stopping at belt replacement.

Carburetor inspection addresses throttle-slide movement, choke components, float needles, seats, and fuel passages. Float height is treated as factory-set, not a routine adjustment. Inlet-valve installation notes identify a specific repair risk: uneven tightening can distort the valves and carburetor coupling.

A separate troubleshooting chapter covers hard starting, poor idle, weak acceleration, overheating, and unstable steering, with references back to the relevant service procedures.

Chassis Repair & Cable Routing

Wheel service includes axle and rim runout checks, bearing inspection, and speedometer-drive checks. Rear brake coverage details cam and wear-indicator alignment; rear shock absorber coverage includes removal, inspection, and replacement.

The steering section warns that incorrectly fitted bearing races can damage the frame. The Guiding Cables drawings identify harness clamps, brake-hose guides, and throttle/choke cable paths, including places where wiring can become trapped during reassembly.

Wiring Diagrams & Exploded Views

The full-system CW50 Wiring Diagram and separate Wiring Diagram (CW50 '00) are supplied as large-format sheets for printing. An Ignition and Starting System circuit diagram supports fault tracing through the CDI, starter relay, switches, and related wiring.

Exploded views titled Crankshaft and Crankcases and Brake Caliper and Disc show component relationships, replacement seals, and assembly callouts.

No-spark charts distinguish ignition-component faults from harness problems, while starter inspection extends to the armature, commutator, brushes, and bearings.

Technical Data & Specifications

Factory reference data includes component-specific tightening torques, lubricant and fluid capacities, cylinder-head distortion and crankshaft runout limits, and piston/ring clearances.

Separate baseline tables identify the DELL'ORTO PHBN 12 HS and TEIKEI 5FX carburetors, with jet-needle, jetting, and pilot air-screw settings. Electrical tables provide CDI source-coil and pickup-coil resistance specifications, ignition-coil test data, charging-system values, and starter wear limits.

Special-tool references include crankcase separator 90890-01135, rotor extractor 90890-01189, and clutch spring retaining tool 90890-01337, identifying the equipment called for during internal repair work.

Working with internal engine components and high-tension electrical systems requires precise measurements and specialized tools. If you are not experienced with factory-level tolerances, always consult a certified Yamaha technician before performing service to ensure the machine remains safe and reliable for the road.