2002 Yamaha TT-R90(R) Service Manual (P/N 5HN-28199-83)

• Factory identity and coverage: A 288-page PDF of Yamaha's English/French/German Owner's Service Manual, first edition April 2002, with cover code 5HN-28199-83 and factory model-code coverage for 5HNB, 5HNC, and 5HND machines.
• Engine repair: Covers carburetor removal and fuel-level adjustment, cylinder-head and camshaft service, valve and valve-spring work, piston and cylinder inspection, and cam-chain timing and tensioner installation.
• Clutch and transmission work: Details the wet multi-disc and automatic centrifugal clutch, kick axle, shift shaft, trochoid oil pump, CDI magneto, crankcase and crankshaft, plus shift-fork, shift-cam, and constant-mesh three-speed transmission service.
• Chassis procedures: Includes wheel and drum-brake service, front-fork removal and disassembly, damper-rod and fork-seal work, steering-head bearing service, handlebar removal, and swingarm and rear-shock removal.
• Electrical diagnosis: Provides component locations, a vehicle wiring diagram, ignition fault-isolation procedures, and carburetor-heating-system tests covering the thermo switch, heater, CDI magneto source coil, and rectifier/regulator.
• Workshop references: Supplies maintenance schedules, cable-routing diagrams, exploded assembly views, job-order charts, torque tables, fluid data, clearance and wear limits, electrical test specifications, and region-specific special-tool numbers.

Routine inspection and maintenance sections are practical for an experienced owner. Internal engine, transmission, fork, and electrical repair sections are better suited to mechanics comfortable with sequential factory procedures, precision measurement, and the listed Yamaha service tools; the manual itself flags certain scheduled jobs as requiring special tools, data, and technical skill.

Model and Publication Coverage

The model table identifies TT-R90R machines for the United States, Canada, Australia, and New Zealand, while TT-R90 applies to Europe and South Africa. It maps 5HNB to the U.S., 5HND to Canada, and 5HNC to Europe, Australia, New Zealand, and South Africa. That regional breakdown is useful when matching the manual to the model name on the bike and when selecting the correct tool-number series.

The covered configuration is the air-cooled SOHC four-stroke single with wet-sump lubrication, a Mikuni VM16SH carburetor, kick starting, a wet multi-disc/automatic centrifugal clutch, and a constant-mesh three-speed transmission. Chassis data is for the front and rear drum brakes, telescopic fork, and Monocross rear suspension. This is Yamaha's factory Owner's Service Manual, not a generic owner's booklet: removal and disassembly sections use exploded views, numbered work sequences, inspection criteria, and reassembly notes.

Engine and Drivetrain Repair Depth

The carburetor chapter goes through removal, disassembly, component inspection, assembly, installation, and float-chamber fuel-level adjustment. Cylinder-head repair continues into camshaft and rocker-arm removal, valve and spring inspection, valve-seat checking and lapping, piston-ring and cylinder measurement, piston installation, and valve-timing setup. The clutch material separates primary-clutch work from friction-plate, clutch-boss, and housing inspection, then carries the repair path through the kick and shift mechanisms.

For deeper repair, the crankcase section assumes the engine assembly has already been removed from the chassis, then covers crankcase separation, crankshaft inspection, and crankcase resealing. It also documents removal and reassembly of the main axle, drive axle, shift forks, and shift cam. The camshaft installation notes warn against turning the crankshaft during assembly because component damage or incorrect valve timing can result. General service instructions also warn that spinning bearings dry with compressed air damages their working surfaces.

Chassis, Electrical, and Diagnostic Material

Wheel sections cover axle, bearing, brake-shoe, drum, and runout inspection. Front-fork coverage includes complete disassembly, damper-rod removal, oil-seal installation, reassembly, and the related oil and service-limit data. Steering and swingarm sections address bearing removal, inspection, lubrication, and installation. The rear shock is covered for inspection, spring-preload adjustment, removal, and complete-assembly replacement; the manual does not provide an internal rear-shock rebuild procedure.

The electrical chapter traces a no-spark condition through the spark plug, connections, engine-stop switch, ignition coil, CDI magneto pickup and source coils, and CDI unit. A separate carburetor-heater chart isolates faults among the wiring, thermo switch, heater, CDI source coil, and rectifier/regulator, with continuity and resistance specifications for testing.

Named visual references include the Cable Routing Diagram and Electrical Components and Wiring Diagram, followed by the Ignition System Inspection Steps and Carburetor Heating System Inspection Steps charts. Exploded job layouts such as Crankcase Separation and Crankshaft Removal and Front Fork Disassembly show the actual depth of the repair coverage without replacing the written procedures.

The special-tool section cross-references U.S./Canadian and international numbers, including the valve spring compressor YM-4019 / 90890-04019, clutch holding tool YM-91042 / 90890-04086, flywheel puller YU-33270-B / 90890-01362, and pocket tester YU-3112-C / 90890-03112. Please remember that working on motorcycles carries inherent physical risks; always ensure you have the proper training, tools, and a safe environment before performing any mechanical service.