2008 Yamaha TT-R110, TT-R110EX Factory Service Manual (P/N LIT-11616-21-48)

• Exact coverage: Written for the 2008 Yamaha TT-R110EX, model 5B61 (U.S.). Coverage is limited to this 2008 configuration; this is not a blanket 2008-2012 publication. Yamaha identifies it as the August 2007 first edition, P/N LIT-11616-21-48, and the manual is a 231-page PDF.
• Engine repair: Factory procedures cover engine removal and installation; cylinder-head and cam-timing work; camshaft, rocker-arm, valve, guide, seat, and spring service; cylinder and piston inspection; oil-pump and rotary-filter service; crankcase separation; crankshaft removal and installation; and bottom-end reassembly.
• Clutch, transmission, and starting systems: Details the wet multi-disc/centrifugal automatic clutch, clutch-release adjustment, 4-speed constant-mesh transmission, shift shaft, shift drum, shift forks, main and drive axles, kickstarter, starter clutch, AC magneto, and starter motor. Inspection, reassembly, and operational checks are included.
• Chassis procedures: Covers front and rear wheel removal, drum-brake shoe and drum inspection, front-fork disassembly and seal work, steering-head bearing service, swingarm inspection, rear-shock removal and installation, and drive-chain/sprocket service.
• Fuel-system service: Includes fuel-tank and fuel-cock checks, Mikuni VM16 carburetor removal and disassembly, jet/float/needle inspection, reassembly, installation, fuel-level measurement and adjustment, throttle and idle settings, plus thermo-controlled carburetor-warmer diagnosis.
• Electrical diagnosis: Separate circuit diagrams and fault-isolation sections cover DC-CDI ignition, electric starting, charging, and carburetor heating. Component tests address switches, fuses, the starter relay, spark-plug cap, ignition coil, starter motor, pickup/lighting/charging coils, rectifier/regulator, thermo switch, and carburetor warmer.
• Shop reference: Provides component-specific torque tables, fluid capacities, lubrication charts, cable-routing drawings, wear limits, clearance data, electrical test specifications, troubleshooting charts, exploded job diagrams, and a dedicated Yamaha special-tool list.

Model and System Scope

The 5B61 identification matters because the manual is built around the air-cooled 110cc four-stroke SOHC single and the carbureted U.S. configuration, including the thermo switch and carburetor warmer. Starting coverage includes both the electric starter and kickstarter. The clutch chapter handles the friction-plate pack and centrifugal primary clutch as separate repair areas, then gives the release-system adjustment and final operating checks. These details keep parts selection and test procedures tied to the configuration documented here.

The periodic-maintenance material goes well beyond an oil-change schedule. It covers valve-clearance adjustment, ignition-timing checks, compression testing, spark-arrester cleaning, drum-brake and drive-chain adjustment, steering-head checks, suspension inspection, spoke tightening, battery service, and emissions-system maintenance.

Repair Depth, Tools, and Diagrams

The special-tool table cross-references U.S./Canada tool numbers with Yamaha's 90890-series equivalents. Representative examples include the YM-A5970 tappet set (90890-01311), YM-01300 damping-rod holder set (90890-01294), YM-04019 valve-spring compressor (90890-04019), YS-01880-A primary-clutch holder (90890-01701), YU-01135-B crankcase separator (90890-01135), and YM-01312-A fuel-level gauge (90890-01312).

The electrical references are split by system: Ignition System Circuit Diagram, Electric Starting System Circuit Diagram, Charging System Circuit Diagram, Carburetor Heating System Circuit Diagram, detailed cable-routing views, and the full TT-R110EX 2008 Wiring Diagram. The general troubleshooting chapter ties symptoms to likely engine, fuel, electrical, clutch, transmission, brake, fork, and handling faults, including starting failures, poor medium-and-high-speed performance, jumping out of gear, clutch slip or drag, overheating, and unstable handling.

The cylinder-head chapter flags a real timing-system trap: turning the crankshaft while the camshaft sprocket is being installed can disturb valve timing and damage the engine. During crankcase repair, Yamaha also warns against striking the mating surfaces or the crankshaft; the separator must be centered and the shaft end protected.

The rear shock section has a clear scope limit. It covers handling, removal, inspection, installation, and disposal of the nitrogen-charged assembly, but not internal shock repair. The manual warns against opening or heating the shock and calls for securely supporting the motorcycle before removal work.