1976-1979 Yamaha RD250, RD400 Supplementary Service Manual
For Yamaha RD250 & RD400: diagnostics, service, and parts for 1976-1979 models. Publication 2R8-28197-80.
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Yamaha Models Covered & Key Technical Specifications
Models: Yamaha RD250, Yamaha RD400
Sub-models / Variants: RD250(C), RD400(C)
Build Years: 1976–1979
Serial Numbers: RD250 Germany: 1A2-310101, RD250 Other areas: 1A2-220101, RD400: 1A3-110101
Technical Data:
- Engine type: Air cooled, 2-stroke forward incline, twin, torque induction system
- Engine displacement: 247 cc (RD250), 398 cc (RD400)
- Compression ratio: 5.8:1 (RD250), 6.0:1 (RD400)
- Ignition system: C.D.I. (Capacitor Discharge Ignition)
- Transmission: 6-speed forward constant mesh
- Fuel tank capacity: 16.5 liters (3.6 imperial gallons)
- Front fork oil capacity: 163.5 ± 4 cc per side
- Spark plug type: N.G.K. B-8ES or B-9ES (varies by market)
- Generated voltage: 14.5 ± 0.5V at 2,000 r/min
- Minimum spark gap: 6 mm (0.24 in) during testing
Yamaha Manual Features & Content Preview
1976–1979 Yamaha RD250 and RD400 Supplementary Service Manual
- Covers 1976–1979 Yamaha RD250 and RD400 models, including the RD250(C) and RD400(C) variants with documented serial number ranges
- Official Yamaha OEM publication 2R8-28197-80, first edition dated December 1977
- Contains 50 pages of technical specifications, including 15 detailed torque tables, ignition timing procedures, and wiring schematics
- Features specialized exploded-view diagrams for the Autolube system, front fork assembly, and engine mounting hardware
- Cross-references specific tool numbers for the flywheel holding and pulling operations
- Accessible from your device as soon as the order is placed
- Laid out for standard letter and A4 printing
- This 1977 first edition documents the essential technical updates and specification changes for the 1976–1979 Yamaha RD250 and RD400 production run
Content Scope and Documentation
This supplementary service manual provides technical data for the Yamaha RD250 and RD400, specifically documenting the revisions needed for the 1976–1979 model cycle. It functions as a necessary companion to the base workshop manual, detailing updated specifications for how factory workshop documentation is structured for these two-stroke machines. The content focuses on precise adjustments for the torque-induction engine, including the Autolube pump, ignition timing, and carburetor synchronization settings.
Technical Data Preview
Section coverage includes engine maintenance, chassis inspection, and detailed electrical system testing. Front fork oil capacity is documented at 163.5 ± 4 cc per side. Transmission oil capacity is listed at 1.7 liters total, with a drain-and-fill requirement of 1.5 liters. Cylinder head nut torque is specified at 1.9–2.1 m-kg. Ignition timing for the RD250 is documented at 1.6 mm B.T.D.C., while the RD400 is set at 2.0 mm B.T.D.C. The electrical data section includes the C.D.I. magneto rotor puller thread size of M27 x P1.0. All service data shown here is for reference only — qualified technicians and the original OEM documentation remain the authoritative source for any hands-on work.
An official Yamaha OEM supplementary service manual covering the 1976–1979 Yamaha RD250 and RD400, documenting technical specifications, engine adjustments, and electrical system data for the C-series production build.
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