1988 Honda TRX250X Repair Manual

The 1988 Honda TRX250X is a sport ATV featuring a 246cc four-stroke engine, 5-speed transmission with reverse, shaft drive, independent rear suspension, front and rear hydraulic disc brakes, and electric start. This repair manual covers complete maintenance procedures, troubleshooting, disassembly, inspection, and reassembly for all major systems including engine, transmission, suspension, brakes, and electrical components.

1. General Information 2. Periodic Maintenance 3. Engine Repair 4. Transmission & Drive System 5. Suspension & Steering 6. Brake System 7. Electrical System 8. Fuel System 9. Troubleshooting Guide 10. Specifications 11. Wiring Diagrams

General Information

Identification: VIN location on frame near steering head. Model: TRX250X. Year: 1988.

Component	Description
Engine Type	246cc 4-stroke, air-cooled, OHC
Bore x Stroke	66.0 x 72.0 mm
Compression Ratio	9.2:1
Carburetor	26mm piston valve
Starting System	Electric starter with auxiliary recoil
Transmission	5-speed with reverse
Drive System	Shaft drive
Suspension Front	Independent double wishbone
Suspension Rear	Swingarm with dual shocks
Brakes Front/Rear	Hydraulic disc

Periodic Maintenance

Regular maintenance intervals and procedures.

Engine Oil: Change every 100 hours or 6 months - capacity 1.9L
Oil Filter: Replace every 200 hours or 12 months
Air Filter: Clean every 50 hours, replace if damaged
Spark Plug: Check/replace every 100 hours - NGK DR8ES-L
Valve Clearance: Check every 200 hours - IN: 0.15mm, EX: 0.20mm
Drive Shaft: Lubricate every 100 hours

WARNING! Always use Honda Genuine parts and fluids. Work on level surface with engine cool.

Engine Repair

Complete engine disassembly and reassembly procedures.

Cylinder Head Removal: Drain coolant, remove cam chain, unbolt head
Piston/Cylinder: Measure cylinder bore, check piston clearance
Valve Service: Lap valves, replace seals, check spring tension
Crankshaft: Inspect bearings, check runout
Camshaft: Check lobe wear, chain tensioner operation
Reassembly: Torque head bolts to 30 Nm in crisscross pattern

CAUTION! Mark all components during disassembly. Use proper torque specifications.

Transmission & Drive System

Transmission Oil: Capacity 0.95L, change every 200 hours
Shift Mechanism: Inspect shift forks, drum, and gears
Clutch: Fiber and metal plates, adjust cable freeplay 10-20mm
Drive Shaft: Inspect universal joints, spline wear
Final Drive: Gear oil capacity 0.19L, check for leaks
Reverse System: Check reverse lockout mechanism

Suspension & Steering

Front suspension: Double wishbone with shocks. Rear: Swingarm with dual adjustable shocks.

Front Suspension: Remove wheel, disconnect tie rods, unbolt upper/lower arms. Inspect ball joints, bushings. Shock absorber oil capacity 325cc per side.

Steering: Check bearing play, lubricate stem bearings. Torque stem nut to 65 Nm. Alignment: Toe-in 0-10mm.

Brake System

Hydraulic disc brakes front and rear. Master cylinder, caliper service procedures.

Brake Fluid: DOT 4, change every 2 years
Pad Replacement: Minimum thickness 1.5mm
Rotor Inspection: Minimum thickness 3.0mm front, 4.0mm rear
Bleeding Procedure: Use Mityvac or manual method
Caliper Service: Clean pistons, replace seals if leaking

Tip: Always clean brake components with brake cleaner only.

Electrical System

12V DC system with CDI ignition, electric start, lighting system.

Battery: 12V 8Ah, check specific gravity 1.260-1.280
Starter: Draw current 90A max, inspect brushes
Charging System: AC generator output 14V 15A at 5000 RPM
CDI Unit: Resistance tests for pickup coil, source coil
Lighting: Headlight 30/30W, taillight 5W
Switches: Check continuity for all control switches

WARNING! Disconnect battery before electrical work. Use multimeter for testing.

Fuel System

26mm piston valve carburetor with accelerator pump.

Carburetor Settings: Pilot screw 2-1/8 turns out, float level 18.5mm, main jet #122, slow jet #38. Accelerator pump: Check diaphragm, spray pattern.

Fuel Tank: Capacity 9.5L including 1.5L reserve. Petcock: ON, RES, OFF positions.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, fuel, compression	Check spark plug, fuel flow, compression (142 psi min)
Hard starting	Valve clearance, carburetor	Adjust valves, clean carburetor, check choke
Poor performance	Clutch slip, restricted exhaust	Adjust clutch, check muffler for restrictions
Transmission noise	Worn gears, low oil	Inspect gears, check oil level and condition
Electrical failure	Battery, stator, regulator	Test charging system components

Specifications

Overall Length: 1755 mm
Overall Width: 980 mm
Overall Height: 1065 mm
Wheelbase: 1185 mm
Ground Clearance: 150 mm
Dry Weight: 192 kg
Fuel Capacity: 9.5 liters
Tire Size Front: 21x7-10
Tire Size Rear: 20x10-9
Brake Fluid: DOT 4

Wiring Diagrams

Complete electrical schematics for entire vehicle system.

Color Codes: R=Red, B=Black, W=White, G=Green, Y=Yellow, Br=Brown, Lg=Light Green, Bl=Blue

Main Harness: From CDI to ignition coil, stator to regulator, battery to starter relay. Lighting circuit: Handlebar switches to headlight, taillight, brake light.

Service: Contact Honda dealer or visit www.helminc.com for original manuals.