Yamaha TT-R90, TT-R90N & TT-R90NC Owner's Service Manual, 2000–2007 (P/N 5HN-28199-81)

This Yamaha TT-R90(N) owner’s service manual, P/N 5HN-28199-81, is the first edition from May 2000. Yamaha lists the TT-R90N for the U.S. outside California, Canada, Australia, and New Zealand, the TT-R90NC for California, and the TT-R90 for Europe.

PDF Search, Bookmarks, and Wiring Detail

Text search and navigation: The PDF contains searchable text. Its bookmarks open the contents pages. Zoom in on the wiring diagram to read the small wire-color codes and connector labels. The French and German component and color-code legends are on the facing page.

The download is one printable 288-page PDF in English, French, and German. The total includes the front and back covers, five memo pages, three maintenance-record pages, and one blank page.

Engine and Clutch Service, Chassis Work, and Electrical Tests

This selection of topics highlights the repair and maintenance coverage. The manual also explains cold and warm starting, engine break-in, and drive chain slack adjustment.

• Engine repair: Cylinder-head removal, camshaft and rocker-arm service, valve and valve-spring inspection, cylinder and piston measurements, and timing-chain installation.
• Clutch and transmission: Wet multi-disc and centrifugal primary clutch service, kick axle disassembly, shift shaft removal, and shift fork, shift cam, and transmission assembly.
• Lubrication and crankshaft: Oil-pump disassembly and rotor clearance checks, rotary filter and oil strainer inspection, crankcase separation, and crankshaft inspection.
• Fuel and routine maintenance: Carburetor disassembly, float-height and fuel-level adjustment, valve-clearance checks, air-filter cleaning, and maintenance interval charts.
• Brakes and chassis: Front-fork seal replacement, wheel-bearing removal, drum-brake service, steering-head adjustment, swingarm removal, and rear-shock spring-preload adjustment.
• Electrical diagnosis: CDI magneto removal, ignition and carburetor-heating troubleshooting charts, a wiring diagram, coil tests, thermo switch checks, and heater resistance testing.

The operating and maintenance sections give owners pre-ride checks and a service schedule. The repair sections serve as a workshop reference for mechanics and experienced owners with engine-service skills, precision measuring tools, and the specified electrical test equipment.

Engine Internals, Clutch, and Transmission

Disassembly and wear checks: Exploded views and job instruction charts show how far each assembly needs to come apart for a given repair. Piston and cylinder drawings show where to take wear measurements. The valve section covers stem-to-guide clearance, seat inspection, and lapping.

Clutch and bottom end: The clutch section distinguishes friction plates, steel plates, and springs from the centrifugal primary clutch and its shoes. Crankcase service includes joint-sealing notes and connecting-rod clearance checks. Transmission illustrations identify the left and right shift forks and their installed orientation.

Tools and assembly: The tool references list valve spring compressor YM-4019 / 90890-04019 and flywheel puller YU-33270-B / 90890-01362. The specifications include compression data, cylinder-head fastening requirements, and general torque charts.

Crankshaft movement during camshaft installation can upset valve timing and cause damage. Excessive force when seating the valve cotters can also damage a valve.

Carburetor Setup and Routine Service

The Mikuni VM16SH carburetor carries identification mark 5HN1 01. Its service section separates jet and needle inspection from float-height and fuel-level adjustment.

Routine service covers throttle-cable and idle-speed adjustment, engine-oil replacement, spark-plug inspection, and spark-arrester cleaning for U.S. models. The maintenance charts distinguish scheduled service from pre-ride checks and account for riding conditions.

Engine exhaust requires adequate ventilation. Keep gasoline and its vapors away from ignition sources.

Forks, Steering, and Drum Brakes

Front-fork disassembly drawings identify the damper rod and oil seal, with special-tool references and refill data. Steering instructions distinguish the initial bearing-seating torque from the final ring-nut setting.

Wheel and brake sections cover bearing removal, wheel runout, brake-lining inspection, and shoe replacement criteria. Rear-shock coverage includes removal, inspection, and spring-preload adjustment. Yamaha specifies replacing a damaged or leaking shock assembly.

Ignition and Carburetor-Heating Diagnosis

The ignition flowchart helps isolate a no-spark fault by checking the spark plug, connections, engine stop switch, and coils before calling for CDI unit replacement. A separate carburetor-heating chart covers the thermo switch, heater, source coil, and rectifier/regulator.

The wiring diagram shows wire-color codes and connector layouts. Cable-routing diagrams show harness and hose placement, and the thermo switch chart gives separate continuity checks for heating and cooling.

Examples of Piston Fit and Carburetor Test Data

The cylinder and piston section specifies a piston-to-cylinder clearance of 0.025–0.045 mm and a service limit of 0.15 mm. The measurement drawings identify the bore and piston skirt dimensions used to determine that clearance.

For the Mikuni VM16SH, float height is 15.5–16.5 mm with the float arm just resting against the needle valve. Compressing the needle valve gives an incorrect reading.

The carburetor heater test specifies 6–10 Ω at 20°C (68°F). The accompanying illustration identifies the terminal and heater body as the measurement points.