Yamaha RD250 & RD400 1976–1979 Service Manual Set (P/N 1A0-28197-80)
506 Pages • ZIP Download: 4 Printable PDFs • 56.26 MB
Yamaha Models Covered & Key Technical Specifications
Models: RD250, RD250C, RD400, RD400C, RD400D, RD400F
Models & Model Codes:
RD250 — 1A2 (European base model, engine 1A2), 2R8 (supplement, engine 1A2), 2T0 (German supplement variant, engine 1A2)
RD250C — 1A0 (general markets, engine 352)
RD400 — 1A3 (European base model, engine 1A3), 2R9 (supplement, engine 1A3)
RD400C — 1A1 (Canada, general markets and U.S., engine 1A1)
RD400D — 1A1 (U.S., engine 1A1)
RD400F — 2V0 (U.S., engine 2V0)
Sub-models / Variants: RD250(C), RD400(C)
Model Years: 1976–1979 (1976, 1977, 1978, 1979)
Serial Numbers: Starting frame and engine numbers
International base manual — RD250(C) Oceania: 352-800101, other general markets: 352-700101, Europe outside Germany: 1A2-000101, Germany: 1A2-100101. RD400(C) Canada and other general markets: 1A1-000101, Oceania: 1A1-100101, Europe: 1A3-000101.
RD250/RD400 supplement — RD250 Germany: 1A2-310101, RD250 Other areas: 1A2-220101, RD400: 1A3-110101.
U.S. manuals — RD400C: 1A1-000101, RD400D: 1A1-100101, RD400F: 2V0-000101.
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Engine type: Air cooled, 2-stroke forward incline, twin, torque induction system
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Engine displacement: 247 cc (RD250), 398 cc (RD400)
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Compression ratio: 5.8:1 (RD250), 6.0:1 (RD400) in the RD250/RD400 supplement. International base models: 6.7:1 (RD250), 6.2:1 (RD400). U.S. RD400C/D: 6.2:1. U.S. RD400F: 10.2:1 (6.7:1 corrected).
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Ignition system: C.D.I. (Capacitor Discharge Ignition) in the RD250/RD400 supplement. Battery ignition with contact-breaker points in the international base manual and U.S. RD400C/D/F coverage.
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Transmission: 6-speed forward constant mesh
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Fuel tank capacity: 16.5 liters (3.6 imperial gallons) in the RD250/RD400 supplement. International base models: 16.5 liters, except Canadian RD400C at 13 liters. U.S. RD400C/D: 13 liters. U.S. RD400F: 16.5 liters.
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Front fork oil capacity: 163.5 ± 4 cc per side in the RD250/RD400 supplement and for the U.S. RD400F. International base models and U.S. RD400C/D: 144 ± 4 cc per side.
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Spark plug type: N.G.K. B-8ES in Germany or B-9ES in other markets covered by the RD250/RD400 supplement. International base models: N.G.K. B-7ES in England and B-8ES elsewhere. U.S. RD400C/D/F: N.G.K. B-8ES.
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Generated voltage: 14.5 ± 0.5 V in the RD250/RD400 supplement and 14.5 ± 0.3 V in the international base and U.S. RD400C/D charging tests, measured at the battery at approximately 2,000 r/min or higher.
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Minimum spark gap: 6 mm (0.24 in) during testing
Yamaha Manual Features & Selected Content Preview
| Publication | Pages |
|---|---|
| 1976 RD250(C)/RD400(C) Service Manual — P/N 1A0-28197-80, 1st ed., January 1976. International base manual in English, French, and German. | 231 |
| 1976 RD400C Service Manual — P/N 1A1-28197-10, U.S. Literature No. LIT-11616-00-02, 1st ed. English. | 95 |
| RD250/RD400 Supplementary Service Manual — P/N 2R8-28197-80, 1st ed., December 1977. Later serial-specific updates in English, French, and German. | 47 |
| RD400 Models ’76–’79 Service Manual — U.S. Literature No. LIT-11616-RD-40, 4th ed., January 1980. English compilation covering the RD400C, RD400D, and RD400F. | 133 |
Yamaha pairs the international supplement with the base manual for the full service procedures. The U.S. compilation pairs RD400C/D base chapters with the RD400F supplement and overlaps with the standalone RD400C edition.
RD250 coverage consists of the 1976 base procedures and later updates keyed to the starting serial numbers. The dedicated 1976–1979 model span applies to the U.S. RD400 compilation.
PDF Navigation and Wiring Detail
Text search and diagram legibility. All four PDFs lack built-in text search and embedded bookmarks. Small wire codes in the international base manual and CDI supplement are legible when zoomed. Some fine labels in the standalone RD400C manual and U.S. compilation remain faint or soft. The compilation also has handwritten notes on its wiring diagrams.
The ZIP contains four printable PDFs totaling 506 pages. That count includes the front and back covers of the standalone RD400C manual, the CDI supplement’s front cover, the appendices, and the 44-page RD400F supplement within the U.S. compilation.
Two-Stroke Overhaul, Brakes, and Electrical Testing
The selected service topics below include major repairs and diagnostic checks. The base manuals also cover fuel petcock service and headlight aiming.
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Engine and transmission. Step-by-step engine removal and reassembly, crankcase separation, crankshaft and transmission inspection, and service for the clutch, primary drive, kickstarter, and shift mechanism.
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Carburetion and Autolube. Carburetor cleaning, inspection, and synchronization, torque-induction reed-valve fault finding, and oil-pump cable, stroke, output, and bleeding procedures.
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Brakes and running gear. Hydraulic disc-brake caliper and master-cylinder repair and bleeding, wheel-bearing replacement, chain and sprocket inspection, front-fork overhaul, and steering-head service.
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Ignition and charging. Contact-breaker and CDI timing procedures, spark and coil testing, charging-system output and resistance checks, and regulator and rectifier tests.
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RD400F updates. Exhaust-emissions service, vacuum-gauge carburetor synchronization, and model-specific changes to the engine, carburetors, disc brakes, and electrical system.
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Factory service data. Maintenance and lubrication schedules, lubricant grades, component torque tables, fluid capacities, wear limits, clearances, and electrical test specifications.
Yamaha wrote the base manuals for mechanics. The RD400F supplement assumes familiarity with motorcycle repair and the use of specialized gauges.
Internal Engine and Chassis Service
Engine inspection. The overhaul chapters cover cylinder and piston repair, bearing and oil-seal service, shift-fork and shift-cam inspection, and final engine mounting. The Autolube pump is factory calibrated and sealed. Disassembly beyond the illustrated service parts can disturb oil delivery.
Chassis variants. The international base manual also covers brake-shoe and drum inspection on RD250(C) rear-drum configurations. Chassis procedures include swing-arm removal and lubrication, rear-shock inspection, tire and tube work, and cable-junction maintenance.
RD400F Emissions and Carburetor Setup
The RD400F supplement covers the exhaust valve, check valve, actuator, and valve opener, with separate periodic emissions checks. Carburetor synchronization and exhaust-valve opener adjustment are linked. Disturbing the factory pilot-air settings can increase emissions, and throttle-control-body disassembly calls for renewed synchronization and opener and idle adjustments.
Wiring, Fault Tracing, and Special Tools
The CDI no-spark chart helps isolate wiring, spark plug, coil, and timing faults before parts are replaced. Visual references include the RD250/400 Wiring Diagram and Cable Routing Diagram, the RD400C Circuit Diagram, and the RD400F wiring diagram and cable-routing views. Exploded views cover the Autolube pump, front forks, and disc-brake assemblies.
Yamaha’s tool references identify clutch holder 90890-01024, dial-gauge stand 90890-01195, and Electro Tester 90890-03021. The CDI supplement lists flywheel holder 90890-01235 and puller 90890-01189. The RD400F supplement specifies vacuum gauge 90890-03094 and exhaust-valve-opener thickness gauge 90890-01293.
Brake hydraulic repair, engine handling, flywheel removal, and live ignition testing carry shop hazards. Use the complete Yamaha procedure, secure the motorcycle, and follow standard workshop safety practices.
Selected Timing and Wear Specifications
The CDI supplement lists ignition timing at 1.6 mm before top dead center for the RD250 and 2.0 mm before top dead center for the RD400.
For clutch inspection, the same supplement gives both models a nominal friction-plate thickness of 3 mm and a wear limit of 2.7 mm. The international base manual specifies a 2 mm lining-thickness wear limit for the RD250(C) rear drum brake.
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