1986–1987 Honda TRX350 FourTrax & TRX350D Foreman Repair Manual (P/N 61T-2000)

• Covers the 1986–1987 Honda TRX350 FourTrax 4x4 and 1987–1989 TRX350D Foreman 4x4. The 350.4 cc powerplant is a single-cylinder, air-cooled four-stroke with chain-driven overhead camshaft, 81 × 68 mm bore and stroke, and an 8.5:1 compression ratio.
• This 303-page PDF reproduces a Honda Service Manual issued in August 1988. The publication identifies Honda Motor Co., Ltd., Service Publications Office and supplies factory specifications, service limits, tightening torques, troubleshooting data, system routing, and model-specific electrical information.
• Repair coverage extends well beyond routine maintenance, including the engine, semi-automatic clutch and transmission, front differential/final drive, suspension and steering, drum brakes, charging and starting circuits, ignition, lighting, oil-cooling controls, and full wiring diagrams.

Component and System Documentation

The engine chapters cover removal and installation as well as internal repair of the cylinder head, valves, camshaft, cylinder, piston, and piston rings. Valve-guide replacement and valve-seat inspection/refacing are documented with dimensional limits and Honda tool references. Camshaft timing, cam-chain tensioner service, cylinder bore measurements, 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.

The drivetrain is equally detailed. The TRX350 uses a wet multi-plate semi-automatic clutch with a five-speed constant-mesh transmission and reverse. Factory procedures cover the centrifugal clutch, change clutch, clutch lifter mechanism, oil pump and primary drive gear, kick starter, starter clutch, gearshift linkage, crankcase separation, crankshaft and balancer, transmission shafts and gears, and output gear. Front differential and final-drive work includes pinion service, bearings and oil seals, gear backlash, bearing preload, and tooth-contact inspection.

Chassis repair sections address front and rear wheels, wheel bearings, drive shafts, steering stem and tie rods, front knuckles, swingarms, shock absorbers, and steering geometry. Brake coverage distinguishes the hydraulic front drum system from the cable-operated rear drum and includes master-cylinder and wheel-cylinder service, shoe inspection, adjustment, and hydraulic bleeding. Fuel-system work includes the fuel tank and pump, air-cleaner case, carburetor removal and overhaul, float-level inspection, pilot-screw setting, and high-altitude carburetor adjustment.

Honda-specific service-tool references include the 07984-2000000 6.5 mm valve-guide reamer, 07923-KE10000 clutch center holder, 07733-0020001 rotor puller, 07924-HA00000 pinion holder, and 07GMK-HA70100 differential inspection attachment. These references are especially useful when planning a repair that calls for more than ordinary hand tools.

Several details show why the factory procedures matter. For valve-guide repair, Honda specifically warns against heating the cylinder head with a torch because the head can warp. During crankcase separation, the case bolts are released in stages and in a cross pattern to prevent crankcase distortion. In the front differential/final-drive setup, incorrect pinion spacer thickness can lock the pinion against the ring gear, so the manual provides backlash and gear-tooth contact checks for the finished assembly.

Wiring, Diagnostics, and Model-Year Differences

Electrical coverage separates the FourTrax CDI ignition from the Foreman DC-CDI system and documents changes between the 1987 and later Foreman configurations. Diagnostic sections cover the ignition coil, pulse generator, alternator, regulator/rectifier, battery charging circuit, starter motor and relay, oil-temperature sensor, cooling-fan control unit, fuel pump and fuel-cut relay, neutral and reverse circuits, lights, and handlebar switches.

Useful diagrams and system views include the Lubrication Diagram, FourTrax CDI and Foreman DC-CDI system diagrams, the Battery/Charging System, Starter System, and Oil Cooling System Diagram. Section 21 then provides complete wiring diagrams for the 1986 FourTrax, 1987 FourTrax, 1987 Foreman, and after-1987 Foreman configurations. That year-specific electrical separation is important when tracing a no-start, charging, fan-control, or switch-circuit problem.

The troubleshooting section works from symptoms rather than individual components. It covers an engine that will not start or is hard to start, loss of power, poor low-speed or idle performance, poor high-speed performance, and poor handling, linking those symptoms to fuel, ignition, compression, clutch, overheating, drivetrain, tire, steering, and suspension checks.

Key Specifications

• Engine oil capacity: 2.8 L (3.0 US qt) at disassembly; 2.3 L (2.4 US qt) after draining
• Intake and exhaust valve clearance, cold: 0.08 mm (0.003 in)
• Cylinder compression: 178–206 psi (12.5–14.5 kg/cm²)
• Ignition timing: 10° ±2° BTDC at 1,400 ±100 rpm, advancing to 30° ±2° BTDC at 3,500 ±100 rpm
• Carburetor idle speed: 1,400 ±100 rpm
• Fuel capacity: 10.5 L (2.8 US gal); reserve is 2.6 L for 1986–1987 models and 2.0 L after 1987
• Front differential oil capacity at disassembly: 135 cc for 1986; 225 cc after 1986. Final-drive capacity at disassembly is 135 cc; Honda specifies SAE #80 hypoid gear oil.

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.