Yamaha TT-R125(R) and TT-R125LW(R) 2002 Trail Bikes Service Manual (P/N 5HP-28199-84)

Yamaha's Owner's Service Manual 5HP-28199-84, First Edition, April 2002, covers the TT-R125R/TT-R125 and TT-R125LWR/TT-R125LW configurations. The 510-page PDF contains the manual in English, French, and German. Its mix of owner-level maintenance and detailed component repair procedures is best suited to experienced owners and technicians who can work from exploded views, factory specifications, and special-tool callouts. Yamaha flags some maintenance jobs as requiring special tools, service data, and technical skills.

• Exact model coverage: TT-R125R for the USA, Canada, Australia, and New Zealand; TT-R125 for Europe and South Africa; TT-R125LWR for the USA, Canada, Australia, and New Zealand; and TT-R125LW for Europe and South Africa.
• Engine repair content: Mikuni carburetor removal, disassembly, inspection, and reassembly; cylinder-head and cam-timing work; camshaft and rocker-arm service; valve and spring inspection; piston and cylinder repair; and oil-pump service.
• Bottom-end and driveline procedures: engine removal, crankcase separation, crankshaft and balancer inspection, wet multi-disc clutch repair, kick-start and shift-shaft service, and transmission, shift-cam, and shift-fork disassembly and reassembly.
• Model-specific chassis work: separate front-wheel and brake chapters for the TT-R125 drum setup and TT-R125LW hydraulic disc setup, along with rear drum brake, front fork, steering, swingarm linkage, and rear shock removal, inspection, and installation.
• Maintenance and adjustment coverage: scheduled and pre-ride checks, valve-clearance adjustment, oil-pressure verification, carburetor tuning, brake bleeding, chain and steering adjustment, suspension inspection, and rear spring-preload setup.
• Electrical and reference material: a color-coded wiring diagram, cable-routing views, no-spark troubleshooting, exploded repair illustrations, component-specific torque tables, capacities, wear limits, clearances, and electrical test specifications.

Model and Configuration Details

The standard model uses code 5HPF for the USA, Australia, New Zealand, Europe, and South Africa, with 5HPG assigned to Canada. The long-wheelbase version uses 5HPH in those same non-Canadian markets and 5HPJ in Canada. These codes matter when matching regional model names and ordering the correct chassis parts.

Both versions use the same air-cooled SOHC single-cylinder engine, Mikuni VM20SS carburetor, kick starter, five-speed constant-mesh transmission, wet multi-disc clutch, and CDI magneto ignition. The chassis chapters make the important differences easy to spot: the standard model has 17-inch front and 14-inch rear wheels with a front drum brake, while the LW has 19-inch and 16-inch wheels with a hydraulic front disc brake. Both retain a rear drum brake and link-type monocross rear suspension.

Factory Repair Depth

The engine sections go well beyond routine tune-up work. Carburetor coverage reaches the throttle valve, jets, float, fuel-level check, inspection, and final installation. Cylinder-head repair addresses timing-chain and tensioner handling, camshaft and rocker-arm inspection, valve-guide and valve-seat work, spring checks, and valve lapping. Piston-to-cylinder inspection, ring checks, crankshaft runout, balancer timing, crankcase assembly, clutch push-lever adjustment, and transmission gear, shaft, cam, and fork inspection are supported by the related limits and assembly data.

Chassis repair is equally specific. The fork chapter covers removal, damper-rod disassembly, seal replacement, oil filling, level setting, and installation. The LW brake chapter includes hose, caliper, piston-seal, master-cylinder, pad, fluid-filling, and air-bleeding work; the standard model receives separate drum-brake procedures. Steering bearings, wheel bearings, spokes, sprockets, swingarm bushings, connecting arms, and relay-arm components each have inspection and reassembly coverage.

Diagrams, Diagnostics, and Special Tools

Yamaha places an exploded view and job-order chart at the start of each removal or disassembly section. Useful examples include the cylinder-head and cam-drive view, clutch and primary-driven-gear assembly, and crankcase/crankshaft/balancer breakdown. The transmission and shift-fork layout, TT-R125LW brake-caliper and master-cylinder assembly, and electrical-component wiring diagram add coverage from other systems. Dedicated cable-routing drawings show the harness, ignition leads, control cables, hoses, and model-specific front brake cable or hose placement.

The ignition chapter follows a practical no-spark fault path through the spark-gap test, engine stop switch, ignition-coil primary and secondary windings, CDI-magneto pickup and charging coils, and CDI unit. Tool references are equally concrete, including the YU-1135-A / 90890-01135 crankcase separator, YM-4019 / 90890-04019 valve-spring compressor, YM-91042 / 90890-04086 clutch holder, and YM-34487 / 90890-06754 ignition checker. Yamaha identifies separate US/Canadian and other-market tool numbers where applicable.

Scope and Repair Cautions

The rear shock chapter covers removal, inspection, preload adjustment, and replacement rather than internal shock rebuilding. Yamaha warns against opening or heating the nitrogen-charged unit because improper handling can damage it or cause it to burst. During camshaft installation, the crankshaft must not be rotated; the manual notes that doing so can cause damage or incorrect valve timing. Brake, steering, engine-internal, and suspension repair should be carried out only with the skill and equipment needed to complete the specified inspections and final safety checks.