1999–2007 Yamaha YH50 Scooter OEM Service Manual (P/N 5EU-AE2)

The 1999–2007 Yamaha YH50 Service Manual is an MBK Industrie publication, second edition, January 1999, carrying cover code 5EU-AE2. Its eight chapters cover maintenance, repair, and troubleshooting for the YH50 scooter.

• Engine repair: Engine removal, cylinder head inspection, piston and ring service, crankcase separation, crankshaft inspection, and reassembly.

• Belt drive and transmission: Primary and secondary sheave disassembly, centrifugal clutch inspection, V-belt checks, and transmission shaft and bearing service.

• Fuel system: Gurtner PY 12 carburetor disassembly, auto-choke testing, vacuum fuel-cock inspection, and reed-valve checks.

• Brakes and chassis: Master cylinder and front caliper rebuilding, hydraulic brake bleeding, rear drum brake service, steering head adjustment, and front fork overhaul.

• Electrical diagnosis: CDI ignition, starter-motor, charging, lighting, and signal-system tests, supported by circuit diagrams and troubleshooting charts.

• Maintenance data: Periodic inspection and lubrication schedules, component torque tables, wear limits, and cable-routing diagrams.

Written primarily for Yamaha and MBK dealers and their qualified mechanics, this manual assumes a working knowledge of scooter repair.

Engine Overhaul, Sheaves, and Autolube Service

Internal engine inspection covers cylinder wear, piston-to-cylinder clearance, piston rings, and crankshaft runout. The Primary and Secondary Sheave exploded view pairs component identification with disassembly tables and assembly notes.

Crankcase procedures identify separating tool 90890-01135 and dedicated crankshaft installation tools. The crankcase section warns against striking gasket mating surfaces during separation because they can be damaged.

Autolube scope: Pump coverage consists of removal, delivery-line and drive-gear inspection, installation, and air bleeding. Internal pump rebuilding is outside that scope.

Carburetor Settings and Auto-Choke Diagnosis

The carburetor specifications distinguish market codes for jets, needle positions, and idle settings. Auto-choke coverage explains the P.T.C. thermistor, wax element, and starter plunger, supported by an Auto Choke System wiring schematic.

Float-height measurement is an inspection procedure. The manual identifies this setting as factory-adjusted and directs inspection of the float, needle valve, and seat rather than adjustment of the float height.

Brake Rebuilding, Steering Bearings, and Forks

Master cylinder and caliper sections include seal replacement, inspection criteria, and reassembly notes. A specific warning explains that solvent cleaning can swell and distort internal brake seals.

The Front Fork Disassembly view distinguishes left- and right-leg components. Steering-head procedures cover bearing-ball and race replacement, while cable-routing diagrams show brake-hose and harness placement during reassembly.

Electrical Fault Tracing and Market-Specific Wiring

The Ignition and Starting System circuit diagram accompanies separate diagnostic paths for no-spark and starter-motor faults. Resistance checks, switch-continuity charts, and connector lead colors help distinguish component faults from wiring problems before replacement.

Complete YH50 wiring diagrams for Switzerland and other markets account for the Swiss license-light circuit. Charging, lighting, signal, and auto-choke tests extend diagnosis to the rectifier/regulator, fuel sender, and oil-level warning system.

Fuel and electrical work should follow the manual’s precautions for flammable vapors, battery gases, and ignition sources.

Sample Idle Settings, Inspection Limits, and Oil Capacities

These examples are a small selection from the manual’s adjustment, inspection, and lubricant-capacity data.

For a warmed engine, idle speed is 1,800 ± 200 r/min for market codes B, E, F, GB, I, and P, and 2,000 ± 200 r/min for D and NL.

Cylinder head inspection specifies a 0.02 mm warpage limit. Transmission oil capacity is 0.11 L for a periodic change, with 0.13 L listed as the total amount.

PDF Navigation, Wiring Detail, and Page Coverage

Text search and diagram navigation: Searchable text and ten embedded bookmarks provide access to the eight chapters and both complete wiring diagrams. Small wire-color and connector labels on the two wide wiring sheets require zooming for comfortable reading.

Supplied as one printable 203-page PDF in English: six opening pages, 195 pages covering the eight chapters, and two final wiring-diagram sheets. Chapter dividers and contents pages are included in the chapter count; all pages are included in the stated total.