Honda TRX350 FourTrax & TRX350D Foreman ATV Repair Manual (1986–1987)

Honda’s August 1988 Service Manual covers the 1986–1987 TRX350 FourTrax 4x4 and 1987–1989 TRX350D Foreman 4x4. It contains factory service information from Honda Motor Co., Ltd., Service Publications Office.

PDF Bookmarks, Diagram Detail, and Page Count

Search and diagram access: PDF text search is unavailable. Embedded bookmarks lead to the contents and all numbered sections. Small wiring labels require zooming, and some of the smallest wire-color codes remain indistinct. Printed troubleshooting pages 23-3 and 23-4 appear before 23-1 and 23-2.

The download is one printable, English-language 303-page PDF: 291 service, reference, and index pages, plus one cover, one safety-notice page, one contents/how-to-use page, and nine memo pages.

Engine Overhaul, 4WD Drivetrain, and Electrical Fault Tracing

The following selected coverage highlights outline the main workshop topics. Other subjects include spark-arrester cleaning and Foreman fuel-meter testing.

• Engine repair: Engine removal and installation, cylinder-head and valve service, camshaft timing, cylinder inspection, and piston and piston-ring replacement procedures.

• Clutch and transmission: Centrifugal and change-clutch repair, clutch-lifter inspection, oil-pump service, kick-starter overhaul, crankcase separation, and internal transmission inspection.

• Differential and final drive: Pinion service, bearing and oil-seal replacement, gear backlash, bearing preload, tooth-contact checks, and limited-slip clutch inspection.

• Brakes and chassis: Drum-brake repair, hydraulic bleeding, wheel-bearing replacement, drive-shaft service, steering adjustments, swingarm work, and shock-absorber disassembly.

• Fuel system: Fuel-tank and pump removal, carburetor overhaul, float-level inspection, throttle-valve synchronization, pilot-screw adjustment, and high-altitude carburetor settings.

• Oil cooling: Oil-cooler, hose, and cooling-fan removal and installation, with troubleshooting for the temperature sensor, fan control unit, and warning indicator.

• Electrical diagnosis: Ignition, charging, starter, lighting, and switch-circuit tests, supported by troubleshooting charts, system diagrams, and model-specific wiring diagrams.

This manual suits mechanically qualified owners and technicians with appropriate tools and measuring equipment; it assumes standard workshop knowledge, and Honda reserves certain safety-related maintenance items for authorized dealers.

Cylinder-Head, Crankshaft, and Transmission Repair

The cylinder-head chapters document valve-guide replacement and valve-seat inspection/refacing, with dimensional limits and Honda tool references. Camshaft-journal measurements, cylinder bore checks, piston-to-cylinder clearance, ring end gap, and cylinder/head warpage checks give experienced owners and technicians the data needed to judge whether parts remain serviceable rather than relying on appearance alone.

Step-by-step procedures address cam-chain tensioner service, crankshaft and balancer removal, transmission shafts and gears, and output-gear setup. Gearshift-linkage and starter-clutch sections distinguish external shift-mechanism faults from problems requiring internal inspection.

Honda warns that torch heating can warp the cylinder head and that uneven crankcase-bolt release can distort the crankcase.

Tool references include the 07984-2000000 5.5 mm valve-guide reamer, 07923-KE10000 clutch center holder, and 07733-0020001 rotor puller. These references are especially useful when planning a repair that calls for more than ordinary hand tools.

Limited-Slip Differential and Final-Drive Setup

The front differential section explains inspection of each clutch pack, slip-torque measurement, and clutch spring-seat selection. Output-gear documentation also covers adjustment shims and gear-tooth contact patterns.

The manual cautions that an incorrect differential spacer can lock the pinion against the ring gear during cover tightening, risking gear or case damage. Relevant tools include the 07924-HA00000 pinion holder, with its specified modification, and 07GMK-HA70100 differential inspection attachment.

Lubrication data distinguish the front differential’s disassembly capacity of 135 cc for 1986 from 225 cc after 1986. Final-drive capacity at disassembly is 135 cc; the specified lubricant is SAE #80 hypoid gear oil.

Drum Brakes, Steering, and Suspension

Brake coverage distinguishes the hydraulic front drums from the cable-operated rear drum. Master-cylinder and wheel-cylinder inspection, shoe wear, adjusters, and rear brake-cam service receive separate treatment.

Chassis sections address steering-stem bearings, tie rods, front knuckles and knuckle holders, drive-shaft boots, rear axle bearings, swingarm pivots, and shock springs. After-1987 front-brake documentation adds waterproof-seal inspection and replacement, brake-panel checks, and diagnosis of water entering the drums.

Brake, steering, driveline, and electrical repair can directly affect vehicle control and safe operation. The manual identifies the required cautions, support points, electrical isolation, brake-fluid handling, adjustment limits, and post-service checks for the systems involved.

Carburetor Service and Fuel Delivery

The dual-valve carburetor section explains synchronization of the piston and butterfly throttle valves. Float-level inspection is covered, but the float itself is nonadjustable; the documented remedy for an incorrect level is float-assembly replacement.

Fuel-system specifications distinguish a 2.6 L reserve for 1986–1987 models from 2.0 L after 1987. Electrical testing covers pump delivery and the fuel-cut relay.

Wiring, Ignition Differences, and Symptom Diagnosis

Electrical coverage separates FourTrax CDI ignition from Foreman DC-CDI and documents changes between the 1987 and later Foreman configurations. Component tests address the ignition coil, pulse generator, alternator, regulator/rectifier, starter motor and relay, neutral and reverse circuits, lights, and handlebar switches.

Diagram examples include the Lubrication Diagram, FourTrax CDI and Foreman DC-CDI diagrams, Battery/Charging System diagram, Starter System diagram, and Oil Cooling System Diagram.

Section 21 provides complete wiring diagrams for the 1986 FourTrax, 1987 FourTrax, 1987 Foreman, and after-1987 Foreman configurations. That electrical separation matters when tracing no-start, charging, fan-control, or switch-circuit problems.

Symptom-based troubleshooting covers hard starting, loss of power, poor idle or low-speed running, poor high-speed performance, and poor handling, linking symptoms to fuel, ignition, compression, clutch, overheating, drivetrain, tire, steering, and suspension checks.

Selected Valve-Clearance and Ignition References

The maintenance section specifies intake and exhaust valve clearance of 0.08 mm (0.003 in), checked cold. Carburetor idle-speed inspection uses a warmed engine and a specification of 1,400 ±100 rpm.

Ignition inspection data specify 10° ±2° BTDC at that idle speed and full advance of 30° ±2° BTDC at 3,500 ±100 rpm. The CDI timing is factory preset; these figures support inspection rather than routine timing adjustment.