1985–1986 Yamaha TT600 / TT600N Service Manual (P/N LIT-11616-04-55)

• Identifies the Yamaha TT600N, model code 55U, from starting VIN *JYA55U00FA000101 and engine number 55U-000101; this is a 200-page PDF containing the August 1984 first edition, Yamaha P/N LIT-11616-04-55**.
• Covers engine removal and internal repair, including cylinder-head and valve service, piston and cylinder inspection, crankcase separation, crankshaft and balancer work, oil-pump service, and cam-timing setup.
• Takes the clutch and constant-mesh five-speed transmission through disassembly, wear inspection, reassembly, adjustment, and operational checks.
• Details the paired primary and secondary Teikei carburetors with sectional views, jet and passage inspection, fuel-level and float-height setting, primary full-open adjustment, and secondary-carburetor synchronization.
• Handles front and rear wheel service, hydraulic front-brake repair and bleeding, fork teardown, and steering-head adjustment. Rear-chassis coverage extends to the Monocross shock, swingarm and relay arm, drive chain, and sprockets.
• Maps CDI ignition and A.C. lighting diagnosis through circuit diagrams, fault charts, spark and output tests, coil checks, cable-routing views, and the full TT600N wiring diagram with conductor color codes.

Built for the Original 55U Configuration

The specifications define an air-cooled, four-stroke SOHC single with dry-sump lubrication, kick starting, a wet multi-disc clutch, and a five-speed gearbox. Carburetion is the Y27PV Teikei primary/secondary arrangement with the 55U 00 identification mark. Chassis data matches the pneumatic-mechanical telescopic fork, gas-and-coil Monocross rear suspension, front hydraulic disc brake, and rear drum brake. Use the model code and starting numbers, rather than the TT600 family name alone, to confirm that this manual matches the motorcycle being serviced.

Yamaha states that the book was written primarily for its dealers and qualified mechanics and assumes a basic understanding of mechanical repair. It is therefore suited to qualified technicians or users with equivalent repair knowledge and shop equipment, especially for internal engine, brake, and suspension work.

Engine and Carburetor Repair Depth

The engine chapter notes that the cylinder head, cylinder, and piston can be removed without taking the engine out of the frame. Bottom-end repair coverage then carries through engine removal, crankcase splitting, crankshaft installation, balancer alignment, transmission and shift-fork assembly, clutch service, kick-start mechanism repair, and oil-pump inspection. Valve work extends beyond adjustment to rocker arms, camshaft and cam-chain components, guides, seats, springs, cylinder-head warpage, and valve sealing checks.

Procedure-specific tools are identified by Yamaha number. Examples include crankcase separator YU-01135, crankshaft installing set YU-90050, and universal clutch holder YM-91042. Carburetor and electrical work call out fuel-level gauge YM-01312 and electro tester YU-33260. Fork service specifies damper-rod holder YM-33962 and seal set YM-08020.

The clutch section distinguishes the Type A and Type B friction plates and the required wave-plate location; an incorrect stack can cause improper clutch operation. During fork disassembly, the manual warns that excessive separating force can damage the seal components or oil-lock piece.

Chassis, Electrical Diagnosis, and Reference Data

Front brake coverage goes beyond routine pad replacement. It documents caliper disassembly, piston and seal inspection, master-cylinder repair, system bleeding, and brake-disc installation. The nitrogen-charged rear shock is treated as a sealed unit: coverage is limited to handling and disposal precautions, removal, spring removal and installation, external inspection, and preload and damping adjustment rather than an internal damper rebuild.

Representative graphics include crankshaft-and-balancer and clutch exploded views, primary/secondary carburetor sectional views, the front-fork assembly, ignition and lighting troubleshooting charts, and the TT600N wiring diagram. The appendices consolidate the periodic maintenance schedule, component-specific torque tables, fluid and lubrication data, inspection limits, clearance specifications, electrical test values, lubrication diagrams, and cable-routing drawings.

Securely support the motorcycle during wheel, fork, steering, swingarm, or engine work. Hydraulic brake service and the pressurized rear shock require the stated factory precautions; incorrect handling can reduce braking performance, damage components, or release stored pressure.