1976–1979 Yamaha RD250, RD400 Supplementary Service & Repair Manual (P/N 1A0-28197-80, 1A1-28197-10)

• Serial-specific model coverage: Covers the 1976 RD250(C)/RD400(C) base machines, later RD250/RD400 changes at the documented starting serial numbers, and the U.S. RD400C/D/F progression through 1979. Coverage is separated by market rather than treated as one blanket serial range.
• Engine repair depth: Follows engine removal through crankcase separation, crankshaft and transmission inspection, clutch and primary-drive service, kickstarter and shift-mechanism work, cylinder and piston repair, reassembly, adjustment, and final mounting.
• Fuel, induction, and lubrication systems: Details carburetor cleaning and inspection, torque-induction reed-valve troubleshooting, dual-carburetor synchronization, Autolube cable, stroke, output, and bleeding work, plus RD400F exhaust-emissions control and vacuum-gauge setup.
• Chassis and brake service: Covers wheel and bearing work, front and rear disc-brake caliper and master-cylinder repair and bleeding, chain and sprocket inspection, front-fork overhaul, steering-head service, swing-arm lubrication and removal, and rear-shock inspection.
• Electrical diagnosis: Provides contact-breaker and CDI ignition diagnosis, timing procedures, spark-gap and coil tests, charging-system output and resistance checks, regulator/rectifier testing, plus model-specific wiring and cable-routing diagrams.
• Factory reference data: Includes Yamaha special-tool cross-references, component-specific torque tables, capacities and approved lubricants, wear limits, clearances, carburetor and Autolube specifications, and electrical test data.

File Breakdown and Coverage Boundaries

506 PDF pages total. The multilingual 1976 RD250(C)/RD400(C) Service Manual uses Yamaha manual identifier 1A0-28197-80, 1st Edition January 1976: 231 pages. The English 1976 RD400C Service Manual carries cover code 1A1-28197-10 and U.S. Literature No. LIT-11616-00-02: 95 pages. The multilingual RD250/RD400 Supplementary Service Manual uses Yamaha document code 2R8-28197-80, 1st Edition December 1977: 47 pages. The English RD400 Models '76-'79 Service Manual is U.S. Literature No. LIT-11616-RD-40, 4th Edition January 1980: 133 pages. The total includes substantial overlap between the multilingual base manual, the English RD400C edition, and the later U.S. compilation; it is not 506 pages of entirely unique material.

The international 1976 specifications list RD400C starting at 1A1-000101 in Canada and other general markets, 1A1-100101 for Oceania, and European RD400 at 1A3-000101. RD250C coverage starts at 352-800101 in Oceania and 352-700101 in other general markets. European RD250 starts at 1A2-000101, with Germany at 1A2-100101. The later supplement applies from RD250 1A2-220101 outside Germany, RD250 1A2-310101 in Germany, and RD400 1A3-110101. The U.S. compilation separately identifies RD400D at 1A1-100101 and RD400F at 2V0-000101.

RD250 coverage is the 1976 base publication plus the later supplement at those starting numbers. The dedicated 1976-1979 model span belongs to the RD400 compilation. Later-build material is supplementary, so it revises the base repair procedures instead of repeating a complete overhaul chapter for every model year.

Variant-Specific Repair Depth

The base overhaul chapters cover crankcase splitting, crankshaft and transmission inspection, bearing and oil-seal service, shifter installation, clutch and primary-drive assembly, cylinder and piston work, engine mounting, carburetor repair, reed-valve fault finding, and Autolube output checks. Chassis sections add wheel-bearing replacement, disc-brake inspection and assembly, hydraulic bleeding, fork disassembly and assembly, steering-head overhaul, swing-arm service, tire and tube work, and cable-junction maintenance.

The later RD250/RD400 supplement carries separate model-specific ignition-timing targets and revised CDI, charging, brake, fork, and specification data. RD400F coverage adds the exhaust-emissions control system—exhaust valve, check valve, actuator, and valve opener—along with periodic emissions maintenance, vacuum-gauge carburetor synchronization, model-specific engine and carburetor revisions, disc-brake changes, and separate electrical data. The exhaust-control setting is tied to carburetor synchronization. Pilot-air settings are factory-set, and the throttle-control body is not treated as a routine disassembly item.

Shop References and Repair Cautions

Named visual references include the RD250/400 Wiring Diagram, RD250/400 Cable Routing Diagram, RD400F Wiring Diagram, multi-page RD400F Cable Routing views, the ignition-system no-spark troubleshooting chart, and exploded service views for the Autolube pump, front forks, and disc-brake assemblies. Yamaha tool references include clutch holder 90890-01024, dial-gauge stand 90890-01195, Electro Tester 90890-03021, flywheel holding tool 90890-01235, flywheel puller 90890-01189, and RD400F vacuum gauge 90890-03094.

The Autolube pump is treated as a sealed, factory-calibrated assembly; opening it beyond the parts shown can alter oil delivery and put the engine at risk. On the RD400F, careless carburetor disassembly can disturb carburetor synchronization and its relationship to the exhaust-control mechanism.

Brake hydraulic repair, engine handling, flywheel removal, and live ignition testing carry real shop hazards. Use the complete OEM procedure, secure the motorcycle, and follow standard workshop safety practices.