1986–1991 Honda CR125R Factory Service & Repair Manual (PN 61460-KRF-A00)

Honda's factory service manual covers maintenance, diagnostics, and repair of the 1986–1991 CR125R, with model-year differences documented throughout its 18 sections.

• Engine and transmission: Engine removal, crankcase separation, crankshaft and gearbox inspection, clutch repair, gearshift-linkage service, and kickstarter disassembly.

• ATAC and HPP: Exhaust-chamber and valve decarbonizing, governor inspection, linkage service, and model-specific exhaust-control adjustments.

• Fuel and intake: Carburetor disassembly, float-level and air-screw adjustments, reed-valve inspection, and temperature- and altitude-based jetting charts.

• Cooling system: Radiator and cap pressure testing, coolant replacement, and water-pump bearing, oil-seal, and water-seal replacement.

• Suspension and steering: Telescopic fork overhauls, Pro-Link rear shock service, swingarm and linkage-bearing replacement, and steering-stem service.

• Brakes and wheels: Drum and hydraulic disc brake service, master-cylinder and caliper rebuilding, air bleeding, wheel-bearing replacement, and spoke adjustment.

• Ignition diagnosis: Ignition-circuit checks, CDI fault isolation, ignition-timing inspection, engine-stop-switch testing, and model-year wiring diagrams.

This manual suits readers with established workshop skills and access to measuring tools and service equipment; standard workshop procedures are not explained in detail.

Engine Repair, ATAC and HPP

Competition maintenance schedules use race counts and running hours. The top-end section covers cylinder-head flatness, piston clearances, ring inspection, and cylinder wear. Port-edge finishing and oversize-piston information apply to the 1986–1988 cylinders; the 1989–1991 cylinder and piston combinations use matched A/B size codes.

ATAC coverage separates the 1986 governor, rack, and cam arrangement from the 1987–1989 linkage. The 1990–1991 HPP pages describe exhaust valves, guides, pinion shafts, and the drive mechanism. These distinctions help identify the correct components and service procedures before top-end work.

Cylinder assembly notes explain how rotating the cylinder during installation can catch a piston ring in a port and break it.

Crankcase and drivetrain: Internal service includes gear-dog and shift-fork inspection, crankshaft runout and connecting-rod clearance checks, and bearing replacement. Exploded transmission views distinguish the earlier gear arrangements from the later assemblies.

Carburetor Tuning and Water-Pump Repair

Carburetor theory links the starting, slow, and main circuits to throttle opening. Jet-needle profile charts, air-screw settings, and temperature/altitude correction charts support tuning for changing race conditions. Reed-valve service covers inspection and replacement of the complete assembly when reeds, stoppers, or seats are faulty.

Cooling-system procedures distinguish radiator-cap testing from system leak checks. Water-pump coverage extends to shaft bearings and both seals, with the water-seal driver identified as 07945-KA30000.

Forks, Pro-Link Suspension and Brakes

Fork procedures distinguish the early assemblies from the later designs, with suspension assembly illustrations, oil-level data, air-pressure baselines, and fork pinch-bolt torques. The installation notes warn that excessive pinch-bolt torque can deform the fork tubes.

The rear shock chapter separates the 1986 remote reservoir from the later integral reservoir. It covers damper-rod rebuilding, oil bleeding, and bladder replacement for 1987–1991. Swingarm pivots, shock-linkage bearings, and steering-stem bearings have their own inspection and replacement procedures.

Suspension setup: Baseline spring preload and handling troubleshooting are included. Detailed preload adjustment for rider weight and damping setup for riding conditions are referred to the Owner's Manual.

Brake coverage distinguishes the 1986 rear drum from the later rear hydraulic disc system. The hydraulic chapter provides piston and bore inspection limits alongside rebuilding and bleeding procedures. Frame dimensions, steering geometry, and wheel-runout checks support chassis inspection.

Review Honda's torque values and hazard notices before dismantling the engine or suspension, particularly the nitrogen-pressurized rear shock.

Ignition Tests and Wiring References

Electrical tables provide model-specific resistance checks for the alternator stator, pulse generator, and ignition coil, along with spark-plug heat-range choices and ignition-timing procedures. CDI diagnosis works by eliminating other ignition faults before unit replacement.

Wiring diagrams cover the different model-year circuits, while cable and harness routing drawings show component connections and wire placement. Troubleshooting flowcharts address hard starting, power loss, and poor running at different engine speeds.

Examples of Head-Nut Torque and Fluid Capacities

These values are a small sample of the manual's engine and chassis torque tables and fluid data; the lubrication section also includes an oil-viscosity chart.

For 1987–1991 models, cylinder-head nut torque is 24–29 N·m. Transmission oil capacity is 570 cc at an oil change and 650 cc after disassembly.

The cooling section lists 750 cc at a coolant change for 1987–1991, with post-disassembly capacities specified separately.

Search, Bookmarks and Printable PDF Contents

Text navigation and wiring detail: An existing OCR text layer supports searches across the service sections, though recognition errors can miss terms; the cover and opening safety notice have no searchable text. Bookmarks cover the chapters and wiring diagrams, with the Maintenance entry landing one page early. Small wiring labels require zooming for comfortable reading.

One printable, English-language 335-page PDF contains 323 service and reference pages, one cover, one safety-notice page, one contents/how-to-use page, and nine memo pages. All are included in the total.