2003 GAS GAS EC 125 / 200 / 250 / 300 Enduro Service Manual (P/N PU010338018)

This GAS GAS service manual covers the 2003 EC 125, EC 200, EC 250, and EC 300 enduro models. The February 2003 edition carries document code PU010338018.

Supplied as one 58-page PDF.

• Engine and cooling: Ignition-timing inspection and adjustment, spark-plug and air-filter service, coolant replacement, and silencer repacking.

• Carburetor tuning: Throttle and idle adjustment, jet and needle selection, and correction charts for changing altitude and temperature.

• Drivetrain service: Transmission-oil changes, hydraulic clutch lever adjustment, drive-chain lubrication and slack adjustment, and rear-wheel alignment.

• Suspension setup: Fork-oil adjustment, spring selection, fork-tube positioning, and rear-shock preload, rebound, and compression settings.

• Brakes and steering: Brake-fluid and pad-wear checks, lever and pedal adjustment, steering-bearing adjustment, and wheel inspection.

• Diagnosis and reference data: Troubleshooting cause/remedy tables, race-based maintenance charts, component-location views, and the factory Torque Table.

EC owners can use the routine maintenance and setup sections, while major engine and transmission repairs are referred to a specialist shop.

Engine, Cooling and Transmission Service

Specifications distinguish the engines by bore, stroke, and displacement. They identify liquid-cooled, crankcase-induction two-stroke construction, KEIHIN PWK 38 carburetion, CDI ignition, and fuel, octane, and premix requirements.

Separate illustrations identify ignition-timing and coolant-drain service points for the EC 125 and EC 200/250/300. Transmission-oil instructions also distinguish the smaller engine from the larger models.

The ignition section explains stator positioning and its effect on power delivery. Drivetrain reference data lists all six transmission ratios, primary and final reductions, and the overall ratio for gearing comparisons.

The Maintenance and Adjustment charts include piston, ring, cylinder, exhaust-valve, and engine-bearing service intervals. Competition preparation adds crankshaft big-end checks and maintenance considerations for dusty or muddy conditions.

Chassis schedules cover brakes, suspension linkage, wheel and steering bearings, fork oil, and rear-shock service.

The cooling section warns that high-pressure washing can damage radiator fins. Unsuitable coolant or hard water can cause corrosion and scale in the engine and radiator passages.

Brakes, Chain and Chassis Inspection

Chassis data identifies the chromoly tubular semi-double-cradle frame and 21-inch front/18-inch rear wheel configuration, alongside brake-disc dimensions and suspension travel.

Brake coverage includes DOT 3/DOT 4 fluid requirements and pad-wear limits; pad replacement is referred to a GAS GAS dealer. Wheel and steering checks address spokes, rim runout, tire bead locks, and steering play.

The final-drive section covers chain elongation, sprocket wear, chain guides and sliders, and master-link clip orientation. Component-location views and the Torque Table support repair work on engine, brake, axle, steering, suspension, and chassis fasteners.

WP, Marzocchi and Öhlins Suspension

Fork specifications distinguish 43 mm WP and 45 mm Marzocchi configurations, with additional Öhlins fork-oil data. Brand-specific oil grades and levels accompany guidance on springs, fork-tube height, and damping.

Fork procedures specify an oil-level gauge and spring holder, with illustrated cap and locknut wrenches. Rear suspension coverage addresses the linkage-type Öhlins shock, spring preload, optional replacement springs, and separate rebound and compression adjustments.

Symptom-based tuning addresses hard or soft forks, excessive brake dive, front-end push or oversteer, rear-end kick over braking bumps, poor rear traction, and bottoming. These distinctions help narrow the choice between spring, oil-level, preload, and damping changes when diagnosing handling complaints.

For fork, steering, brake, wheel, and rear-shock work, support the motorcycle securely and follow the manual's inspection and tightening precautions before riding.

Carburetor Tuning and Fault Finding

The carburetor discussion explains how the main jet, slow/pilot jet, jet needle, clip position, and air screw affect different throttle ranges. The Standard Settings table distinguishes unleaded and leaded fuel combinations, including N1EC and N1ED needles and throttle-valve cutaway specifications.

The altitude/temperature Correction Factor graph and Jet Needle/Air Screw Chart relate atmospheric changes to jetting adjustments. Course-specific gearing and front/rear suspension balance are also discussed.

Troubleshooting tables address starting problems, overheating, power loss, abnormal engine or drivetrain noise, clutch slip or drag, and jumping out of gear. Further entries cover steering, suspension, and brake faults.

Speedometer Instructions and Repair Scope

GAS GAS speedometer instructions cover the clock, trip display, km/h or mph selection, backlight connections, and 21-inch enduro/17-inch supermoto wheel settings. A complete electrical wiring diagram is not included.

The manual concentrates on maintenance, setup, inspection, troubleshooting, and selected repair procedures. It does not provide a complete internal engine or transmission overhaul, including crankcase separation and bottom-end rebuilding.

PDF Contents and Navigation

The total includes 54 pages of instructions and reference material (printed pages 64–117), two warranty pages, and the front and back covers. Embedded PDF text supports searching; there are no PDF bookmarks. The text is primarily English, with occasional Spanish passages.