1986–2007 Honda CR125R Service & Repair Manual (OEM)

• 620 PDF pages total — a 290-page Honda factory service manual for 2000–2003 (P/N 61KZ463), the 125-page 1998 Honda Owner’s Manual & Competition Handbook (P/N 31KZ4690), and a 205-page CR80R/CR125R Part A workshop extract from Haynes Book No. 2222 covering 1986–2001. No 2004–2007 CR125R repair coverage is included.
• Covers engine removal, cylinder-head/cylinder/piston service, crankcase separation, crankshaft and transmission repair, clutch/kickstarter/gearshift work, reed-valve inspection, cooling-system testing, and water-pump repair.
• Follows the CR125R exhaust-control changes from the 1986 butterfly-valve and 1987–1989 rotary-valve versions of the Automatic Torque Amplification Chamber (ATAC) through the 1990–1999 Honda Power Port (H.P.P.) system and the 2000–2003 Radical Combustion (RC) valve, with removal, inspection, decarbonizing, assembly, and adjustment where applicable.
• Includes carburetor removal and overhaul, float-level checks, minor and major adjustment, spark-plug reading, special-condition tuning, and separate altitude/temperature jetting charts for 2000, 2001, 2002, and after-2002 configurations.
• Details fork and rear-shock service, race-sag and track-condition adjustment, steering-head and swingarm/linkage work, wheel and drive-chain service, hydraulic brake bleeding, and master-cylinder/caliper repair.
• Provides year-by-year engine and frame identification tables, model-specific wiring diagrams, 2000–2001/2002/after-2002 cable and harness routing, ignition peak-voltage and timing checks, troubleshooting charts, special-tool numbers, torque tables, capacities, clearances, and wear limits.

What Each Publication Adds

The August 2002 Honda factory service manual is the main reference for the later bikes. Its specifications and procedures distinguish 2000, 2001, 2002, and “After 2002” builds rather than treating them as one unchanged model. This split matters in the carburetor, ignition, brake, suspension, drive-chain, air-cleaner, and routing sections. The “After 2002” data supplies the 2003 coverage.

The 1998 Honda Owner’s Manual & Competition Handbook is more than an operating booklet. It combines scheduled and between-race maintenance with a substantial disassembly/assembly section for the engine, H.P.P. system, clutch and transmission, cooling system, steering stem and fork, rear suspension, wheels, hydraulic brakes, and ignition. Its race-oriented material covers plug-color reading, carburetor tuning, race sag, track-specific suspension changes, fork height and steering geometry, wheelbase, gearing, tire selection, and maintenance/racing log sheets. It is not the separate 1998 Honda Shop Manual.

For the earlier years, the Haynes material groups the CR80R and CR125R in the book’s Part A chapters. The 205-page PDF contains those Part A sections, shared introductory workshop material, troubleshooting, wiring diagrams, and the index; the CR250R/CR500R Part B chapters referenced in the contents and index are not present. The CR125R coverage contains year-by-year engine and frame number tables and identifies the mechanical changes that separate the 1986–2001 models.

Engine, Fuel, and Ignition Coverage

The liquid-cooled two-stroke engine chapters cover in-frame top-end work, engine removal and installation, crankcase pressure/vacuum diagnosis, crankcase splitting, bearing and seal replacement, crankshaft and connecting-rod inspection, transmission and shift-drum service, clutch repair, kickstarter service, and final assembly checks. The later Honda manual also makes clear which jobs can remain in the frame and which require engine removal.

Fuel-system information reflects the actual design changes. The older Haynes section distinguishes the earlier slide-carburetor layouts from the flat-slide design used on 2000-and-later CR125R models. The factory manual then separates 2000–2001 and after-2001 carburetor assemblies and gives year-specific baseline settings and tuning charts. Reed-valve inspection, air-cleaner housing service, fuel-tank/filter work, expansion-chamber removal, and silencer packing are covered alongside carburetor repair.

Useful factory tool references include the carburetor float-level gauge 07401-0010000, clutch-center holder 07724-0050002, flywheel puller 07733-0010009, peak-voltage adapter 07HGJ-0020100, and 46 mm fork-seal driver 07TMD-MAC0100.

Chassis, Diagrams, and Repair Cautions

Suspension coverage combines workshop repair with race setup. The manuals address fork removal and disassembly, seal and bushing inspection, oil-level setup, steering-head service, rear-shock and linkage work, and swingarm bearings. Separate procedures cover wheel bearings, spokes, chain alignment, brake-disc inspection, caliper and master-cylinder overhaul, and brake-system bleeding.

Visual references include the year-grouped cable and harness routing views, altitude/temperature jetting charts, H.P.P. and RC valve assembly illustrations, crankshaft/transmission exploded views, fork and shock-linkage drawings, and model-specific wiring diagrams with ignition test points. These are backed by component torque tables, fluid-capacity data, inspection limits, electrical test specifications, and troubleshooting for hard starting, low- and high-speed performance, shifting, cooling, braking, and handling faults.

Several cautions are specific enough to prevent expensive damage. The 1998 handbook identifies the coated cylinder as non-reboreable and calls for correctly matched replacement components. Honda’s later procedure warns that rotating the cylinder during installation can snag the piston ring in a port and break it, while improper cylinder-head loosening can distort the head. The electrical and brake sections also flag ICM damage from disconnecting a live circuit and master-cylinder cup damage if the sealing lips turn inside out.

Fuel work, hot pressurized coolant, nitrogen-charged shock service, and hydraulic brake repair involve fire, scalding, stored-pressure, and chemical hazards; ignition testing also requires the manual’s current-isolation precautions. Follow the safety procedures and service-equipment requirements in the applicable publication.