1987 Yamaha YZ125 Service Manual
Troubleshooting, parts diagrams, and service data for the 1987 Yamaha YZ125 engine, chassis, and electrical systems. Includes comprehensive coverage and part numbers. VIN JYA2HG000HA000101.
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Models Covered & Key Technical Specifications
1987 Yamaha YZ125 (JYA2HG000HA000101) Service Manual — Technical Compendium Licensed Strategic Compendium | Motorcycle Library.
- Designated Power Rating: 94.5 kg (208 lb) specifies the total dry weight of the motorcycle.
- Primary Power Draw: For optimal operation, the YZ125 requires a liquid-cooled 2-stroke, single-cylinder engine configuration.
- Advanced Thermal Rating: The compression ratio is set at 8.4 - 10.5 : 1 to ensure efficient combustion.
- Defined Unit Dimensions: The bore and stroke measure 56 x 50 mm (2.205 x 1.969 in) for optimal performance.
- Key Interference Fit: The clutch type is wet, multiple-disc, ensuring smooth power transfer.
- Certified Baseline Requirements: The frame type is a semi double cradle design, providing stability and support.
Manual Description & Preview
1987 Yamaha YZ125 Repair Manual: Motorcycle Service Manual for Yamaha YZ125, 1987 edition Wiring-Compendium
Design-Core: YZ125 / Yamaha Motor Corporation, Ltd // Engineering-Metrics: Motorcycle / Engine Logic // Design-Core: Technical-Data.
Technical Specifications Overview
| Assessment-Parameter | Value | Calibration-Standards |
|---|---|---|
| Engine Type | Liquid cooled 2-stroke, gasoline | Standard |
| Bore x Stroke | 56 x 50 mm (2.205 x 1.969 in) | Specification |
| Compression Ratio | 8.4 - 10.5 : 1 | Specification |
| Horsepower | Not Specified | - |
| Fuel Type | Premium gasoline with an octane rating of at least 90 | - |
The manual presents information on engine maintenance and repair, including the carburetor and reed valve, cylinder head, cylinder, and piston. It details procedures for the clutch, kick axle, shift shaft, and primary drive gear, as well as the YPVS governor, CDI magneto, and crankshaft assembly. Systems such as the transmission and shifter are also covered, alongside detailed diagrams and part numbers.
Engine Maintenance Procedures
This document outlines procedures for engine removal, disassembly, inspection, and repair. It covers critical components like the cylinder head, piston, and crankshaft, providing step-by-step guidance for each. The manual also includes details on the power valve and its maintenance.
Transmission and Shifter Systems
Information on the transmission and shifter components, including inspection, repair, and assembly, is thoroughly documented. This section ensures proper functioning of the gear system for optimal performance.
Troubleshooting and Specifications
Comprehensive troubleshooting guides for common issues are provided, alongside detailed general and maintenance specifications. This includes torque specifications for various components to ensure proper pivot-point integrity.
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