1986–1987 Yamaha TT225 / TT225S Factory Service & Repair Manual (P/N LIT-11616-05-18)

• 199-page Yamaha OEM PDF — P/N LIT-11616-05-18, 1st Edition, November 1985 — for the TT225S, model code 1RH, with starting VIN *JYA1RH00GA000101 and engine starting number 1RH-000101**.
• Covers engine removal, complete teardown, inspection, repair, reassembly, and remounting of the 1RH engine, including the cylinder head and cam chain, camshaft and rocker arms, piston/cylinder, crankshaft and connecting rod, balancer, oil pump, clutch, kickstarter, six-speed transmission/shifter, crankcases, bearings, and oil seals.
• Periodic service procedures include valve-clearance and decompression-cable adjustment, ignition-timing and compression checks, engine-oil/filter service with oil-flow verification, clutch adjustment, brake and drive-chain service, fork-oil change, steering-head and wheel-bearing checks, and headlight service.
• The Y26P/TK-KIKAKI carburetor section provides a section view plus disassembly, inspection, assembly, fuel-level adjustment, and throttle adjustment; chassis repair coverage includes the front disc brake, wheel bearings, front fork, steering head, Monocross rear suspension, swingarm/linkage, and drive chain.
• Electrical diagnosis includes the TT225S circuit and wiring diagrams, CDI magneto, pickup/source coils, ignition coil, ignition and lighting troubleshooting charts, complete ignition-system checks, spark-gap testing with the YU-33260 Electro Tester, and switch-continuity checks.
• Factory service references include special-tool P/Ns such as the YM-91042 clutch holder, YM-01080 rotor puller, YM-08035 valve-adjusting tool, and YM-01300-1 front-fork cylinder holder, along with engine/chassis/electrical specification tables, component torque data, lubrication diagrams, and cable-routing drawings.

This Yamaha factory service manual is built around the TT225S 1RH configuration rather than generic small-displacement motorcycle service. The general specifications identify a 223 cc, four-stroke SOHC four-valve single-cylinder engine, wet-sump lubrication, kick starting, CDI magneto ignition, and a constant-mesh six-speed transmission. Yamaha states that the book was written primarily for its dealers and qualified mechanics and assumes a basic understanding of motorcycle repair technology, so the procedures are aimed at users who already understand normal shop practice and measuring equipment.

Engine Overhaul and Assembly Coverage

Chapter 3 is the core repair section. It documents full engine removal and remounting, while also noting that piston, clutch, carburetor, and AC-magneto work can be carried out without removing the engine. Internal service runs through cylinder-head and valvetrain work, cam-chain and decompression-cam service, piston and cylinder inspection, crankshaft/connecting-rod checks, oil-pump inspection, clutch and primary-drive repair, transmission and shifter inspection, kickstarter service, crankcase work, and bearing/oil-seal inspection.

Reassembly is treated as its own factory procedure, not merely the reverse of teardown. The manual covers crankshaft and balancer installation, transmission/shifter assembly, crankcase closure, oil pump and clutch installation, piston/cylinder assembly, CDI rotor and cam-chain installation, camshaft/rocker-arm assembly, cylinder-head timing, and final adjustments. Exploded assembly views are placed ahead of disassembly sections to identify component order and relationships.

Carburetor, Chassis, and Electrical Diagnosis

The carburetion chapter goes beyond cleaning and basic adjustment, with a carburetor section view, component inspection, reassembly, and factory fuel-level and throttle-adjustment procedures. Chassis work includes front and rear wheel service, wheel-bearing replacement, front brake pad replacement, caliper and master-cylinder disassembly/inspection/assembly, brake bleeding, fork disassembly and reassembly, steering-head service, and swingarm/rear-arm linkage inspection. The rear-shock section is limited to handling, removal, inspection, and installation rather than an internal shock overhaul.

Electrical coverage is diagnostic rather than schematic-only. Useful illustrations include the TT225S circuit diagram, ignition-system circuit diagram, lighting-system circuit diagram, carburetor section view, lubrication diagrams, and full TT225S wiring diagram. The ignition chapter also traces no-spark/weak-spark faults through plug, cap, coil, pickup/source-coil, switch, connection, and CDI checks, while the lighting section provides its own fault-finding chart and switch tests.

Factory Specifications and Shop Cautions

The appendix consolidates general, engine, chassis, and electrical maintenance specifications, including component-specific tightening data, clearances and wear limits, capacities, gearing, carburetor settings, suspension and brake data, and electrical test values. A general torque chart, lubrication diagrams, cable-routing drawings, and unit definitions round out the reference material.

Several cautions show the level of assembly detail Yamaha expects. During cam timing work, incorrect camshaft rotation can cause piston and valve damage. The manual also warns against spinning bearings dry with compressed air because the bearing surfaces can be damaged. Brake hydraulic work and pressurized fork/shock service should be performed with the manual's stated safety precautions and specified fluids and handling practices.