1987–1992 Yamaha YSR50T Factory Service & Repair Manual (P/N LIT-11616-06-05)

• Factory coverage: Yamaha YSR50T, model code 2RR, beginning with VIN JYA2RR00*HA000101 and engine serial 2RR-000101. This is the first edition, March 1987, P/No. LIT-11616-06-05, supplied as a 232-page PDF.
• Engine overhaul: Covers removal and remounting, top-end disassembly, crankcase separation, crankshaft and five-speed transmission service, shifter and kick-start mechanisms, clutch/primary drive, CDI magneto, and measured inspection before reassembly.
• Fuel and lubrication: Details the Mikuni VM16SH carburetor and reed valve from removal through inspection and adjustment, plus Y.E.I.S. hose checks and Yamaha Autolube cable, pump-stroke, output, and air-bleeding procedures.
• Chassis repair: Includes wheels and bearings, front hydraulic disc and rear drum brakes, caliper and master-cylinder service with system bleeding, front-fork overhaul, steering-head setup, Monocross rear suspension/swingarm work, and chain/sprocket replacement.
• Electrical diagnosis: Provides the YSR50T circuit and wiring diagrams, color codes, component locations, and fault-isolation charts for CDI ignition, sidestand/neutral interlocks, charging, lighting, signals, horn, and instrument warning/indicator circuits.
• Factory reference data: Adds periodic maintenance tables, cable-routing drawings, exploded assembly views, component torque tables, fluid specifications, wear limits, clearances, electrical test values, and Yamaha special-tool callouts.

2RR Coverage and Intended User

This is the factory shop manual for the original air-cooled, reed-valve YSR50T/2RR configuration with Yamaha Autolube, a wet multi-disc clutch, five-speed constant-mesh transmission, front disc/rear drum brakes, and six-volt electrical equipment. Yamaha wrote the manual primarily for dealers and qualified mechanics, and it assumes the reader already understands basic motorcycle repair principles. Use the model code and starting numbers for fitment; this file contains the base manual only, with no later-year supplements or addenda.

Scheduled Service and Full Engine Overhaul

Routine service is organized around the factory schedule rather than a generic checklist. It covers bodywork access, idle and control-cable setup, spark-plug and ignition-timing checks, transmission-oil and clutch service, air-filter, fuel-line, Y.E.I.S., and exhaust inspections, brake and drive-chain adjustments, steering and wheel checks, battery and fuse testing, and headlight aiming.

The overhaul chapter goes well beyond top-end repair. It follows engine removal, cylinder head/cylinder/piston inspection, clutch and primary drive, kick axle, shift shaft, CDI magneto, crankcase splitting, transmission and crankshaft inspection, then assembly and installation. Factory data cover cylinder condition, piston and ring fit, crankshaft alignment and bearing condition, clutch wear and warpage, gear dogs, shafts and shift forks, crankcase oil passages, and Autolube delivery components. Carburetor coverage includes float height and running fuel-level adjustment with the Yamaha gauge, not just jet identification.

Chassis Repair and Electrical Fault Finding

Brake work distinguishes pad replacement from caliper and master-cylinder teardown, then covers inspection, resealing, reassembly, and bleeding. Fork, steering-head, swingarm/rear-shock, wheel-bearing, brake-drum, drive-chain, and sprocket chapters include removal, installation, and condition checks.

Electrical charts trace no-spark or intermittent-spark faults, starting-interlock problems, no-charge conditions, and failures in the headlight, taillight, turn signals, horn, neutral light, and oil-warning circuit. Tests are tied to switch continuity, coil resistance, generator output, and wiring checks. The separate troubleshooting chapter also addresses hard starting, poor idle or high-speed running, gear jump-out, clutch slip/drag, kick-start faults, weak brakes, fork leaks, unstable handling, lighting/signal failures, and overheating.

Wiring, Exploded Views, and Yamaha Tooling

Each major disassembly section is supported by an exploded assembly view. Named visual references include the full YSR50T Wiring Diagram, multi-page Cable Routing drawings, crankshaft/transmission/shifter assemblies, the clutch and primary-drive view, the front-brake caliper/master-cylinder layout, and ignition/charging/lighting diagnostic charts. Tool callouts identify the YM-01312 Fuel Level Gauge, YM-91042 Universal Clutch Holder, YM-01189 Flywheel Puller, YU-01135 Crankcase Separating Tool, YU-90050/YM-90063 crankshaft installer set, YU-33261 Coil Tester, and YU-03112 Pocket Tester.

YSR50T Repair Cautions

The crankcase procedure warns against forcing a case half that hangs up or striking a gasket surface; either mistake can damage the aluminum mating faces. The fork data are side-specific: the spring is fitted to the left leg and Yamaha gives separate oil-quantity and oil-level specifications for each side, so treating both legs alike can cause incorrect fork operation and leakage.

Securely support the minibike before engine, wheel, steering, or suspension work, and follow the manual's brake-fluid, battery-electrolyte, fuel/fire, and ignition-test precautions. Brake and electrical safety checks should be completed before returning the motorcycle to service.