1998–2001 Honda TRX450S / TRX450ES Foreman ATV Service Manual PDF

This Honda service manual covers the 1998–2001 TRX450S Fourtrax Foreman and TRX450ES Fourtrax ForemanES, with procedures for the foot-shift model and the ES model’s Electric Shift Program (ESP).

• Engine repair: Engine removal, cylinder-head and piston inspection, valve-train service, and crankshaft and balancer disassembly.
• Fuel and lubrication: CV carburetor disassembly, fuel-system troubleshooting, trochoid oil-pump inspection, and lubrication-system service.
• Clutch and transmission: Centrifugal and change-clutch service, gearshift-linkage repair, and internal constant-mesh transmission inspection.
• Front and rear drive: Front differential overhaul, drive-shaft service, and rear final-drive backlash and gear-contact checks.
• Chassis and brakes: Double wish-bone suspension, steering inspection and toe adjustment, hydraulic front drum-brake bleeding, and mechanical rear drum-brake service.
• Electrical and ESP diagnosis: Charging and starting tests, DC-CDI ignition checks, electric-shift troubleshooting, and separate model-specific wiring diagrams.

Written for readers with basic maintenance knowledge of Honda motorcycles, scooters, or ATVs, this manual assumes familiarity with standard workshop procedures.

Engine Repair and Maintenance Coverage

The engine chapters distinguish work possible with the engine installed from jobs requiring removal. Cylinder-head service extends to valve-guide replacement and valve-seat reconditioning; piston and cylinder inspection includes dimensional checks and wear limits. Cylinder-head torque tables accompany the inspection data. Crankcase procedures cover the crankshaft, balancer, and transmission assemblies.

Maintenance procedures cover the air cleaner, spark plug, valve clearance, engine oil and filter, brakes, and suspension. However, printed pages 3-3–3-4 are missing from this PDF: the maintenance schedule and the dedicated fuel-line and throttle-operation checks listed in the contents are absent.

The lubrication-system diagram supports oil-pump and oil-cooler service. The manual specifically warns that installing the oil filter backward can cause severe engine damage.

Frame, body-panel, and exhaust sections document removal and installation, while cable and harness routing drawings show component relationships around the chassis. Observe standard shop safety practices and use appropriate protective equipment when handling fuel, supporting the ATV, or servicing the brakes.

CV Carburetor Service

Fuel-system coverage includes the vacuum piston and diaphragm, starting-enrichment valve, air-cutoff valve, primer, float, and jets. Pilot-screw adjustment and high-altitude setting procedures are included, alongside a closed-crankcase emission-control schematic.

Carburetor service notes warn that compressed air can damage the diaphragms. Float inspection specifies gauge 07401-0010000.

Clutch, Transmission, and Final Drives

Exploded clutch assembly views accompany disassembly and inspection procedures, with component-specific torque data for reassembly. Separate transmission illustrations identify the TRX450S and TRX450ES arrangements; the technical-features section explains changes to the ES transmission’s gear dogs for motor-operated shifting.

Front driving-mechanism coverage includes the hypoid gears, differential clutch pack, bearing replacement, and gear-contact checks. Drive-shaft procedures cover the inboard joint, but the outboard joint cannot be disassembled. Rear final-drive procedures include pinion-bearing service, shim selection, and tooth-contact inspection.

Electrical Fault Tracing and ESP

ESP troubleshooting charts address failure to shift, faults during operation, abnormal gear-position indication, and reverse selection. They separate mechanical transmission or linkage problems from control-motor, angle-sensor, switch, and wiring faults, helping narrow a shifting complaint before choosing which assembly to service.

The ESP system diagram shows how its controls and sensors connect. Other electrical chapters cover alternator and regulator/rectifier tests, ignition peak-voltage checks, starter-motor inspection, and relay testing. The recoil starter and starter clutch have their own disassembly and inspection procedures.

Preview of Valve, Spark Plug, and Float Specifications

For both models, intake and exhaust valve clearance is specified at 0.15 mm with the engine cold, below 35°C/95°F, at compression-stroke top dead center. Spark plug service specifies a gap of 0.8–0.9 mm.

Carburetor float level is specified at 18.5 mm with the float valve seated and the float arm just touching it. The float is not adjustable; the manual calls for replacement of the float assembly if its level is outside specification.

PDF Navigation and Page Count

Bookmarks and wiring detail: PDF text search is not available. Embedded bookmarks link to the contents and the 25 numbered sections. Small wiring labels require zooming, and fine lettering remains soft in places. Each model’s wiring diagram spans two PDF pages.

Supplied as one 424-page printable PDF, including the cover, three introductory pages, and 11 memo pages.