2007–2008 Honda TRX420 Rancher Service Manual (P/N 61HP401)

• Coverage: A 498-page PDF for 2007-2008 Honda TRX420TM, TRX420TE, TRX420FM, and TRX420FE FourTrax Rancher models. TM is 2WD with a left-foot gearshift, TE is 2WD with Electric Shift Program (ESP), FM is 4WD with a left-foot gearshift, and FE is 4WD with ESP.
• Engine repair sections document engine removal and installation, cylinder-head disassembly, valve-guide replacement and seat refacing, camshaft service, cylinder/piston inspection, and final assembly checks.
• Clutch and transmission coverage includes the centrifugal clutch, change clutch, gearshift linkage, crankcase separation, transmission, shift drum and forks, crankshaft, balancer, alternator, and starter clutch.
• For FM/FE 4WD models, the manual covers front drive shafts, the propeller shaft, front final clutch, final-drive removal and teardown, bearing replacement, gear-tooth contact and backlash inspection, and reassembly. Rear axle and final-drive repair applies across the covered range.
• Chassis procedures include wheel hubs and knuckles, suspension arms, shocks, steering shaft and tie rods, toe adjustment, swingarm service, front master-cylinder and caliper repair, brake-fluid replacement and bleeding, and rear drum-brake service.
• Diagnostic material combines PGM-FI and ESP DTC charts, symptom troubleshooting, connector and component-location views, system schematics, electrical test data, and separate full wiring diagrams for TM/FM and TE/FE configurations.

Honda directs this service and repair information to qualified professional technicians and assumes prior basic maintenance knowledge of Honda motorcycles, scooters, or ATVs. It is therefore suited to trained mechanics with the test equipment, special tools, and shop-safety background required for fuel-injection, drivetrain, and electrical diagnosis rather than to a first-time owner looking for basic operating instructions.

Engine, Transmission, and Final Drives

All four versions use a liquid-cooled PGM-FI single-cylinder engine, an automatic centrifugal and multi-plate wet clutch arrangement, and a constant-mesh five-speed transmission with reverse. On TM/FM models, “foot shift” means the rider selects gears with the left pedal; it is not a hand-operated manual-clutch setup. TE/FE models replace the pedal-operated shift input with the handlebar-controlled ESP system.

The top-end chapters go well beyond routine adjustment. They cover compression testing, rocker arms, pushrods, valves, valve guides and seats, camshaft timing, cylinder wear, piston rings, and related service limits. Cylinder-head and cylinder/piston work can be performed with the engine in the frame. Crankcase, transmission, crankshaft/balancer, alternator, and starter-clutch service requires engine removal, and the manual provides the corresponding removal, teardown, inspection, assembly, and installation procedures.

Final-drive work is treated as a setup job, not just parts replacement. The front and rear gearcase chapters include pinion and ring-gear inspection, tooth-contact pattern and backlash checks, bearing and seal replacement, and the specified setup data. Steering and suspension repair is backed by inspection limits and alignment data, while the brake section covers both the hydraulic front discs and mechanical rear drum system.

PGM-FI, ESP, and Electrical Diagnosis

The fuel-injection section provides system and connector maps, symptom charts, a DTC index, MIL readout and erasing procedures, PCM/ECM terminal checks, fuel-pressure and flow testing, and circuit diagnosis for the MAP, TP, ECT, IAT, bank-angle, vehicle-speed, injector, fuel-pump, and idle-air-control circuits. TE/FE diagnosis adds ESP pre-checks, shared PGM-FI/ESP fault logic, shift-angle and gear-position sensor tests, gearshift-switch checks, and shift-control-motor/reduction-gear service.

Named visual references include the PGM-FI system diagram, lubrication-system diagram, cooling-system flow pattern, battery/charging and ignition system diagrams, the ESP system diagram, and the TM/FM and TE/FE wiring diagrams. Component-specific torque data, fluid capacities, pressure-test specifications, electrical values, clearances, wear limits, and lubrication and sealant maps are placed with the related repair sections.

Special Tools and Shop Cautions

Honda tool callouts include the SCS connector 070PZ-ZY30100, HDS pocket tester TDS 3557-0112-01, fuel-pressure gauge 07406-0040004, and differential inspection tool 07KMK-HC50101, along with the required pullers, drivers, holders, reamers, and locknut adapters.

The manual warns that disturbing the white-painted throttle-body fasteners can cause throttle-body malfunction, and that clamping a final-drive gearcase too tightly can damage the housing. It also distinguishes actual fastener torque from the torque-wrench reading when Honda’s leverage-increasing adapters are used. Fuel-system work involves pressurized gasoline, hot cooling-system service can cause scalding, and opened brake hydraulics require correct bleeding and contamination control; follow the manual’s safety procedures and equipment requirements throughout the repair.

Coverage is limited to the 2007-2008 TM/TE/FM/FE models identified above. This is not the service manual for TRX420FA/FPA configurations or later model-year revisions.