Honda CR125R 1984–1985 Workshop Manual

• Covers 1984–1985 Honda CR125R motocross competition motorcycles in a 255-page PDF of Honda’s shop manual.
• Engine repair includes cylinder and piston inspection, crankcase separation, transmission service, and crankshaft bearing replacement.
• The ATAC system section covers governor disassembly, rack and cam inspection, and butterfly valve adjustment.
• Separate fuel system chapters detail piston-valve carburetor overhaul, float-level adjustment, reed valve inspection, and tuning for racing conditions.
• Cooling system procedures cover radiator cap and system pressure testing, coolant replacement and air bleeding, and water pump seal and bearing replacement.
• Chassis work extends to front fork and Pro-Link shock overhaul, suspension linkage bearings, hydraulic front brake master cylinder and caliper repair, and rear drum brake service.
• Ignition diagnosis includes stator and coil tests, ignition timing checks, engine stop button testing, and a wiring diagram.

This manual is suited to mechanics already familiar with motorcycle repair; detailed explanations of standard workshop procedures are not included.

Model-Year Differences and Service Data

The water-cooled two-stroke engine has separate cylinder, piston and clutch spring specifications for each model year. Cooling coverage distinguishes the earlier mechanical water pump seal from the later water seal design.

It includes transmission oil capacities, spark plug recommendations and torque tables for engine and chassis fasteners, including cylinder head nuts and the flywheel nut. Coolant capacities distinguish routine changes from filling after disassembly, while inspection limits support engine and chassis wear checks. The Competition Maintenance Schedule uses running hours and race counts.

Engine Service and ATAC

Engine removal and installation coverage identifies work that requires the engine out: the crankshaft, six-speed constant-mesh transmission, shift drum and shift forks. Cylinder head, wet multi-plate clutch and external shift linkage service can be performed with the engine installed.

The ATAC (Automatic Torque Amplification Chamber) system has operating views in the Technical Features section, explaining the governor linkage and valve position. Its adjusting screw restores the valve setting after service.

Reboring notes explain how an incorrectly shaped exhaust port bridge can cause piston seizure. Cylinder installation cautions also identify the risk of catching and breaking piston rings on a port.

Special tool references include crankcase puller 07937-4300000 and crank assembly kit 07965-1660100.

Carburetor Calibration

For trackside tuning, the publication lists jetting recommendations based on altitude and temperature correction factors. The 1984 PE35D and 1985 PJ01A piston-valve carburetors have separate settings and assembly instructions; the latter also has a combined choke/idle-speed control.

The Carburetor Operation chart shows which circuits influence each throttle range, while the Jet Needle/Air Screw Chart links correction factors to adjustment choices. These baselines apply to an unmodified engine using the specified premix; modified engines or different mixtures require corresponding calibration changes.

Suspension Repair and Setup Limits

Suspension repair includes shock oil replacement, air bleeding and reservoir service. The 1985 damper rod procedures extend to seal holder, piston and damping valve disassembly; the 1984 instructions call for damper rod replacement if its seal leaks.

The shop manual supplies standard spring preload data and handling troubleshooting. It directs detailed adjustment for rider weight and riding conditions to the separate Owner’s Manual. Shock service requires a proper nitrogen charging system.

Electrical Test Equipment and Troubleshooting

The Engine Lacks Power troubleshooting chart connects checks with likely causes in the fuel, ignition, compression and drivetrain systems. Other charts address hard starting, faults at low and high engine speeds, and poor handling.

Separate CDI resistance tables apply to each model year, with readings specific to the listed Sanwa 07308-0020000 or Kowa TH-5H testers. The manual warns that another tester can give false readings. Cable and Harness Routing drawings support reassembly.

Always observe standard shop safety protocols and use properly calibrated torque wrenches on engine and suspension fasteners.