KYMCO VENOX 250 / 250i Service Manual (P/N T100RB50AA)

• Covers the KYMCO VENOX 250 and VENOX 250i as identified in the publication, including the carbureted VENOX 250 and the AFI (Automatic Fuel Injection) VENOX 250i. The manual does not state a VIN or engine-serial-number range; December 2006 is the edition date, not an explicitly stated model-year limit.
• KYMCO factory publication P/N T100RB50AA, First Edition, December 2006, presented here as a 243-page PDF.
• Organized into 19 technical sections covering periodic inspection, lubrication, fuel delivery, engine removal, cylinder heads and valves, crankshaft/piston/cylinder service, clutch and transmission, cooling, chassis, brakes, ignition, charging, starting, instruments, switches, and AFI diagnosis.
• Includes system illustrations, cable and harness routing views, troubleshooting flowcharts, special-tool references, and separate wiring diagrams for the VENOX 250 and VENOX 250i.

Manual Organization and Content

This KYMCO service manual goes well beyond routine maintenance. Engine repair coverage includes engine removal and installation, camshaft and rocker-arm service, cylinder-head disassembly, valve and guide inspection, crankcase separation, crankshaft runout checks, piston and ring measurement, cylinder-bore inspection, and connecting-rod/crank-bearing selection. The bearing-choice tables use crank, crankcase, and connecting-rod identification marks to select Brown, Green, or Yellow bearing shells. Clutch and drivetrain sections cover the one-way starter clutch, wet multi-disc clutch, gear-shift mechanism, transmission forks and drum, mainshaft/countershaft gears, bearing replacement, and the five-speed transmission.

The carbureted VENOX 250 uses a KEIHIN CVK carburetor with a 30 mm venturi, #110 front and #108 rear main jets, 17.5 mm/19.0 mm front/rear float levels, and twin-cylinder vacuum/CO adjustment data. The VENOX 250i receives a separate AFI section built around the ECU, fuel pump and relay, front/rear injectors, WTS, O2/O2-heater sensor, MAP, T-MAP, TPS, ISC, tilt switch, crank-position sensing, and the diagnostic connector. Fuel pressure is specified at 2.5 bar, and the throttle-body bore is 32 mm.

AFI troubleshooting is unusually detailed for a manual of this age. It documents CELP blink-code diagnosis without a scan tool as well as PDA-based diagnosis using the KYMCO diagnostic cable and Dtool 5.0. The PDA material covers DTC loading/clearing, live signal data, idle CO adjustment, and component-function checks for items such as the cooling-fan relay, check-engine lamp, and O2-heater relay. The referenced PDA, cable, and diagnostic software are external service equipment; they are described by the publication but are not part of the PDF.

Factory procedures that commonly move a job beyond ordinary owner maintenance include engine removal, cylinder-head and valve repair, crankshaft/piston service, bearing selection, flywheel removal, clutch and transmission teardown, steering-stem and wheel-bearing service, hydraulic brake bleeding and master-cylinder/caliper overhaul, cooling-system pressure testing, thermostat and water-pump inspection, carburetor synchronization, and AFI fault diagnosis. Representative visual references include Cable & Harness Routing, the Generator/Left Crank Case Cover assembly views, Cooling System Schematic Drawing, ignition and starting-system diagrams, the AFI System Diagram/System Location views, and the final VENOX 250/250i wiring diagrams.

Specification Highlights

The 249.4 cc engine is specified with DOHC-8V valve gear, a 58 x 47.2 mm bore and stroke, 11:1 compression ratio, and a five-speed transmission. Valve clearance is 0.10 mm intake and exhaust, with cylinder compression at 17 ± 2 kg/cm². The lubrication section gives an oil-pump output pressure of 2.4 kg/cm² at 1000 rpm and rotor/pump-body service limits. Cooling data includes a 0.9 ± 0.15 kg/cm² radiator-cap relief pressure, thermostat opening at 80 ± 2°C and full opening at 90°C, plus listed capacities of 560 cc for the radiator and 240 cc for the reserve tank.

Chassis and brake data is equally specific: DOT-4 brake fluid, 3.0 mm front brake-disc thickness service limit, 0.3 mm disc-runout limit, 161.3 mm rear brake-drum I.D. limit, 400 cc of SAE 10W fork oil per front fork, and 99 cc of SAE 5W per rear shock. Electrical testing includes ignition-coil resistance of 3.57–4.83 ohms primary and 14.96–20.24 kΩ secondary with plug cap, pulser-coil resistance of 396–594 ohms, and charging-system limit voltage of 14.5 ± 0.5 V at 5000 rpm. The manual also distinguishes charging output: 10.5 A minimum at 1500 rpm for VENOX 250 and 11.5 A minimum for VENOX 250i.

Special-tool references are identified by tool number, including flywheel holder E021, flywheel puller E042, valve spring compressor E040, piston installer E041, clutch lifter holder E047, lock-nut socket wrench E046, bearing remover E030, bearing driver handle E014, vacuum/CO adjuster E043, and vacuum gauge E045.

Several manual-specific repair cautions are worth knowing before teardown. The oil-filter screen must not be installed backward; KYMCO warns that reversed installation can damage the engine. The one-way clutch mounting bolt uses a left-hand thread, so treating it like a conventional fastener risks damaging the bolt or threads. On the 250i, the throttle body is factory preset: disturbing its painted screws can upset throttle/idle synchronization, and connecting or disconnecting the ECU with the ignition switched on can damage the ECU.

Engine removal calls for an engine stand or floor jack to support and maneuver the powerplant. Fuel-system work, hydraulic brake service, cooling-system pressure work, and electrical disconnection each have dedicated safety precautions in the manual.

Please note: This page is a contents and specification overview of the KYMCO publication. It does not reproduce the manual’s step-by-step repair instructions.