Yamaha YZ250(G)/LC (4MX Series) Factory Service Manual (P/N 4MX-28199-80)

Whether you are a professional mechanic prepping a race bike or a DIY rider doing a weekend top-end rebuild, this 575-page official Yamaha PDF publication (P/N 4MX-28199-80) delivers the exact factory clearances needed for the 1995 YZ250. It covers European, USA, and international variants.

Working on high-performance two-strokes requires precision. Always use the proper specialized tools outlined in this guide and follow standard workshop safety protocols to prevent component damage or personal injury during teardowns.

Designed to streamline your daily workshop routine, this manual provides a clear advantage by centralizing all critical wear limits and factory rebuild procedures directly at your workbench. This eliminates the need to rely on incomplete aftermarket data or forum advice when tackling complex overhauls.

• Comprehensive system data: Features 47 torque-specification tables, 2 wiring schematics, and strict component-inspection criteria for the entire chassis and 249 cc liquid-cooled engine.
• Competition-level tuning: Documents fluid change schedules, baseline setups, and proper storage procedures to prevent metal deterioration during extended downtime.
• Essential maintenance: Outlines targeted troubleshooting procedures, complete engine removal, and major repair sequences for the water pump.
• Detailed teardown coverage: Provides deep-dive inspection steps for the YPVS governor, PWK38 Keihin carburetor, CDI magneto, reed valve, shift cam, and rear shock absorber.

Skip the expensive dealership labor rates by utilizing the step-by-step instructions for high-cost jobs like front fork oil seal replacements, brake system air bleeding, complete clutch overhauls, and transmission gear inspections. To guarantee accurate reassembly and proper routing, this guide includes highly detailed exploded diagrams, cable routing diagrams, job instruction charts, disassembly illustrations, and general torque specifications charts.

When servicing these 4MX-model powerplants, technicians frequently encounter heavy carbon accumulation within the YPVS governor and power valve linkages. If ignored, this buildup can severely restrict the exhaust port timing and cripple mid-range performance. Another common pitfall involves the water pump impeller shaft developing deep grooves over time. Failing to identify this wear during inspection will inevitably allow coolant to bypass the seals and contaminate the transmission oil.

Technical Data & Clearances

This guide reflects the industry standard for how factory workshop documentation is structured, providing structured technical data for the 4MX-model architecture. Key reference points include:

• Cylinder bore: 68.000–68.014 mm
• Piston ring end gap: 0.55–0.75 mm
• Transmission oil capacity: 0.75 liters (for periodic changes)
• Cylinder head nuts torque: 28 Nm

Get the factory reference trusted by professional workshops to keep your YZ250 running at peak competitive performance.