1987 Yamaha YZ125 Service Manual

1987 Yamaha YZ125 Service Manual Technical Scope

• Covers 1987 Yamaha YZ125 motocross motorcycles equipped with the liquid-cooled 2-stroke engine and semi double cradle frame design
• Original OEM publication including illustrated symbols for maintenance, lubrication, and fastener torque specifications
• Contains 47 exploded-view diagrams, 15 service torque tables, and detailed maintenance intervals for race-readiness
• Accessible from your device as soon as the order is placed
• Suitable for printing individual sections for shop-floor use
• Indexed PDF search covers every chapter and appendix
• OCR text layer lets you jump to a torque spec by keyword
• Re-download the file any time, no expiration
• This 1987 first edition serves as the foundational technical reference for the 2HG-series YZ125 engine and chassis maintenance

Component Maintenance Documentation

The 1987 Yamaha YZ125 service manual organizes technical information into seven core chapters covering general information, maintenance, engine repairs, cooling systems, chassis, electrical, and detailed appendices. Maintenance chapters provide technical guidance for carburetor tuning, reed valve inspection, and exhaust system servicing. The documentation transitions into engine-specific details including cylinder head, piston assembly, and YPVS governor diagnostics. Separate sections detail transmission and shift shaft assembly, providing torque values for internal fasteners and bearing clearances.

Specification and Reference Data

Engine performance data lists bore and stroke dimensions at 56 x 50 mm and a compression ratio range of 8.4 to 10.5 : 1. Cylinder head bolt torque values are documented at 30 Nm (21 ft-lb) in a cross-recess sequence. Spark plug gap is specified at 0.5–0.6 mm in the ignition timing table. Standard ignition timing is set between 1.06 and 1.36 mm before top dead center. Clutch plate wear limits are defined as 2.7 mm for plates and 0.05 mm for warping. Access how factory workshop documentation is structured to refine your mechanical approach. Note: This page is a contents overview for the manual. It does not provide repair or diagnostic instructions. An official Yamaha OEM workshop manual covering the 1987 Yamaha YZ125, documenting engine, chassis, electrical, and performance specifications for the JYA2HG-series build.