Yamaha TT-R90(R) (5HN-series) 2003–2004 OEM Shop Manual (P/N 5HN-28199-83)

• Yamaha Owner's Service Manual No. 5HN-28199-83 in a 285-page PDF, with the material presented in English, French, and German.
• Model coverage is identified by Yamaha codes: TT-R90R 5HNB (USA), 5HND (Canada), and 5HNC (Australia/New Zealand); TT-R90 5HNC (Europe/South Africa).
• Engine repair coverage runs from VM16SH carburetor removal, disassembly, inspection, assembly, and fuel-level setting through cylinder-head, camshaft/rocker-arm, valve, cylinder, piston, and ring work, then crankcase separation and crankshaft inspection.
• Drivetrain procedures cover the wet multi-disc/centrifugal automatic clutch, kick axle, shift shaft, oil pump and strainer, CDI magneto rotor, shift forks, shift cam, and constant-mesh 3-speed transmission.
• Chassis sections detail front and rear wheel and drum-brake service, wheel bearings, front-fork removal and disassembly, fork-seal installation, handlebar and steering work, swingarm service, and rear-shock removal and preload adjustment.
• Electrical material includes a wiring diagram with wire-color codes, cable-routing views, ignition fault isolation, spark-gap/engine-stop/coil/CDI-magneto tests, and carburetor-heater/thermo-switch diagnostics.
• Factory tables provide torque specifications, fluid and lubricant data, wear and service limits, clearances, electrical values, maintenance intervals, and region-specific special-tool numbers.

This factory manual goes well beyond routine owner maintenance. Yamaha organizes the repair procedures in a sequential format, with exploded assembly views and job charts identifying removal order, parts, quantities, and operation notes. It is suited to experienced owners and mechanics who can use measuring equipment and the specified service tools; Yamaha marks certain scheduled jobs as requiring dealer-level tools, service data, and technical skills.

Engine, Drivetrain, and Fuel-System Repair

The carburetor chapter covers removal, complete disassembly, jet and passage inspection, needle-valve and float checks, reassembly, installation, and fuel-level adjustment. Routine tuning sections add throttle free-play, pilot-air screw, idle-speed, and valve-clearance procedures. The engine chapter then works through cylinder-head and cam-timing service, rocker-arm shaft removal, valve and spring inspection, valve-seat lapping, cylinder and piston measurement, ring inspection, and reassembly.

Bottom-end coverage includes clutch plate and centrifugal clutch inspection, kick and shift mechanisms, oil-pump rotor and strainer checks, CDI magneto removal, crankcase separation, crankshaft inspection, and transmission teardown. The job charts identify the transmission shafts and gears, shift forks, guide bar, and shift cam, followed by final shifter and transmission operation checks. One scope limit matters: the crankcase procedure assumes the engine assembly has already been removed from the chassis; there is no separate engine removal and installation chapter.

Chassis, Electrical, and Diagnostic Coverage

The chassis chapter provides front and rear wheel removal, wheel-bearing service, drum-brake inspection, front-fork disassembly and seal replacement, steering service, and swingarm removal. Rear-shock coverage is limited to external inspection, spring-preload adjustment, and removal rather than an internal shock rebuild.

Useful visual references include the cable-routing diagram, carburetor exploded view, cylinder-head and camshaft job views, clutch and transmission exploded assemblies, front-fork disassembly view, and the electrical components/wiring diagram. Electrical fault charts trace no-spark complaints through circuit connections, the engine-stop switch, ignition coil, pickup and source coils, and CDI unit. A separate chart covers the thermo switch, carburetor heater, CDI source coil, and rectifier/regulator. The electrical chapter is confined to the CDI ignition, engine-stop, and carburetor-heating circuits shown; it does not cover a battery or road-lighting system.

Factory Data, Special Tools, and Repair Cautions

The specifications chapter supports repair decisions with component-level torque tables, dimensions, allowable clearances, wear limits, fluid capacities, lubricant requirements, and electrical test values. The tool list distinguishes North American YM/YU/YS/ACC numbers from international 90890-series numbers. It pairs the valve-spring compressor YM-4019 with 90890-04019 and the clutch holder YM-91042 with 90890-04086. The flywheel puller is YU-33270-B/90890-01362; fork work calls out the YM-1300/90890-01294 damper-rod holder and dedicated seal drivers.

The cylinder-head section warns that rotating the crankshaft during camshaft installation can cause damage or incorrect valve timing. General assembly guidance also warns against spinning cleaned bearings with compressed air because it damages the bearing surfaces.

The TT-R90(R) is a single-rider, off-road youth motorcycle intended for operation under adult instruction and supervision. Repair work involving gasoline, a hot engine or exhaust, brakes, or a raised machine requires secure support, proper ventilation, and the safety precautions specified in the manual.