Yamaha YZ250(P)/LC Owner's Service Manual Competition Motocross Bike (2002)

Yamaha YZ250 (P)/LC Owner's Service Manual – Professional Competition Motocross Machine Guide (2002)

Step up your maintenance game with the definitive factory-grade resource for the 2002 Yamaha YZ250 (P)/LC. This isn't just a basic set of instructions; it is the comprehensive Owner's Service Manual specifically engineered for Yamaha’s pacesetting racing machines. Whether you are a professional mechanic or a dedicated rider, this manual provides the highest grade of technical craftsmanship and reliability information to keep your bike at peak performance on the closed course.

This manual is tailored for the 250cc class competition motocross bikes and covers every technical nuance of the liquid-cooled, 2-stroke reed-valve engine that has made the YZ series a leader in its class.

Engine and Performance Specs

The heart of your YZ250 is a precision-tuned 249cc single-cylinder, forward-inclined engine. This manual gives you the exact specifications needed for professional tuning:

• Engine Type: Liquid-cooled 2-stroke, gasoline
• Bore x Stroke: 66.4 x 72 mm
• Compression Ratio: 9.1~10.6:1
• Fuel System: Premium unleaded gasoline with a 30:1 premix ratio (Yamalube 2-R recommended)
• Carburetion: Detailed settings for the KEIHIN PWK38S, including main jet (#175/#178) and pilot jet (#50/#52) configurations for different regions.

Comprehensive Maintenance and Repair

From routine inspections to complete engine overhauls, this guide utilizes a sequential, step-by-step format with easy-to-read exploded diagrams.

• Top-End Service: Critical data for cylinder head warp limits (0.03 mm), piston-to-cylinder clearance, and ring end gap measurements.
• Chassis & Suspension: Complete service procedures for the semi-double cradle frame and the sophisticated telescopic front forks (46 mm inner tube) and link-type monocross rear suspension.
• Transmission: Professional guidance for the constant-mesh 5-speed transmission, including clutch plate wear limits and gear ratio breakdowns.

Vital Serial Number Identification

For positive identification and theft protection, the manual highlights where to find your machine's unique identifiers:

• Vehicle Identification Number (VIN): Stamped on the right side of the steering head pipe (USA, CDN, AUS, NZ, E models).
• Frame Serial Number: Located on the right of the steering head pipe (F, D, GB, I, ZA models).
• Engine Serial Number: Stamped into the elevated part of the right-side crankcase.
• Model Label: Affixed to the frame under the rider's seat, essential for ordering correct spare parts.

Technical Table of Contents

• General Information: Machine identification, special tools, and control functions.
• Specifications: Maintenance and general torque specs for every bolt and nut.
• Regular Inspection: Pre-operation checks and maintenance intervals to ensure race-day reliability.
• Engine/Chassis/Electrical: In-depth teardown and assembly instructions.
• Tuning: Professional settings for the YPVS governor, carburetor jetting, and suspension clickers.

Maximize the capabilities and the reliability of your machine. This manual ensures you have the technical knowledge to perform safe and proper maintenance, from the F.I.M. minimum machine weights (98 kg/216 lb for the 250cc class) to precision ignition timing.