Yamaha RD250/RD350 & DS7/R5C Service Manual, 1972–1973 (P/N SVM-360-0800-20)

This Yamaha factory Service Manual covers the 1972 DS7 and R5C and 1973 RD250 and RD350 (P/N SVM-360-0800-20). It combines the DS7/R5C service material originally printed in September 1972 with additions for the RD models.

PDF Access, Wiring Detail, and Page Count

Text search and diagram detail: PDF text search is not available, and there are no embedded PDF bookmarks. Small labels and wire-color codes in the circuit diagrams require zooming for comfortable reading.

The ZIP download contains one printable English PDF with 113 pages, including five preliminary pages and two unnumbered circuit-diagram pages. The contents lists a separate Cable Routing Diagrams appendix, but that appendix is not included in this PDF.

Two-Stroke Engine, Chassis, and Electrical Service

The following are selected service topics, rather than a complete contents list. Additional subjects include air-cleaner service and tachometer-drive gear removal.

• Engine repair: Step-by-step procedures for engine removal, top-end inspection, clutch service, crankcase separation, and transmission, kick-starter, and shifter disassembly and assembly.

• Autolube and induction: Minimum pump-stroke inspection, pump and carburetor adjustment, oil-pump bleeding, cylinder-porting explanations, and reed-valve inspection.

• Chassis and brakes: Model-specific front-wheel arrangements, hydraulic brake service, wheel-bearing replacement, fork teardown, swingarm inspection, and steering-head maintenance.

• Charging-system diagnosis: Charging-output checks, regulator resistance tests, rectifier diode testing, alternator winding and brush inspection, and battery troubleshooting.

• Ignition service: Breaker-point inspection and adjustment, condenser testing, static and running ignition-coil tests, spark-plug diagnosis, and dial-gauge timing procedures.

• Factory illustrations: Model-specific porting diagrams, clutch and transmission section views, brake-system drawings, steering-head exploded views, and separate R5C/DS7 and RD250/RD350 circuit diagrams.

Its level of repair detail is best suited to experienced mechanics and restorers who can work with micrometers, dial gauges, ohmmeters, torque wrenches, and model-specific service tools.

Model and Drivetrain Differences

Separate reduction-ratio tables and shift-fork layouts distinguish the DS7/R5C transmissions from the RD units. Carburetor data identifies the DS7’s VM26SC units and the VM28SC units used on the other three models.

Model-specific cylinder-porting drawings show the different engine arrangements rather than treating them as interchangeable. The foreword also identifies the R5’s larger bore, different primary ratio, and larger rear tire. These distinctions help match the assembly layout and service data to the machine being repaired.

Engine Inspection and Reassembly

Top-end coverage addresses cylinder wear measurement, reboring and honing for oversize pistons, piston and ring inspection, pin and small-end bearing fit, and carbon removal from the head, piston, and ports.

Bottom-end detail includes clutch plate and spring checks, primary-drive service, connecting-rod play, crankshaft runout, crankshaft seal positioning, and shifter adjustment. Assembly illustrations identify thrust washers, bearing locations, retaining clips, and shift-fork positions.

Named shop equipment includes the armature puller or shock puller, chain removal and clinching adapters, and the 350 YR1 clutch-holding tool. Yamaha bearing-fitting and fork-holding tools are also referenced; ignition testing uses a dial-gauge adapter, Point Checker, and Electrotester.

Incorrect clutch thrust-washer or bearing placement can let the clutch boss rub the primary driven gear, while incorrect piston-ring or piston orientation can damage rings and cylinder surfaces.

Autolube, Carburetors, and Reed Valves

The Autolube chapter treats the oil pump as a precision assembly and concentrates on external inspection, adjustment, synchronization, and bleeding rather than internal pump overhaul.

Carburetor coverage connects float-valve condition and contamination with overflow problems. It also provides passage-cleaning guidance, throttle-slide synchronization, idle adjustment, and separate factory jetting tables.

Reed-valve inspection addresses the valve, stopper, gasket, and fasteners, with assembly-replacement guidance when these components cannot seal or operate correctly.

Drum Brakes, RD350 Disc Brake, and Suspension

The DS7, R5C, and RD250 front-wheel sections cover the two-leading-shoe drum brake, rim runout, spoke tension, lining inspection, and drum condition.

The RD350 has separate fixed-caliper disc-brake coverage extending to caliper and master-cylinder disassembly, piston and seal inspection, pad and disc limits, reassembly, hose and pipe installation, and bleeding. The manual warns that mineral oil or alcohol can swell brake cups and seals, and specifies replacement of caliper bridge bolts after removal.

Fork illustrations distinguish the DS7/R5C, RD250, and RD350 assemblies. Related sections address fork-seal replacement, swingarm-bushing wear, steering-head ball races, tire service, and inflation guidance for different riding conditions.

The rear shock is a non-serviceable assembly; its section covers leakage diagnosis and replacement criteria rather than internal rebuilding.

Electrical Fault Isolation and Reference Material

Charging-system troubleshooting follows the battery, regulator, alternator, rectifier, and main-switch circuit. Component-specific meter connections and resistance tables support fault isolation before an assembly is replaced.

Ignition coverage explains point wear, cam-follower wear, condenser faults, coil performance, and spark-plug condition. Timing instructions address both cylinders and their relationship to point-gap adjustment.

Appendices provide metric/US conversion tables, general fastener torque data, and an explanation of Yamaha’s parts-number structure. Model-specific parts catalogs and Service or Parts News Bulletins remain separate references.

Working on vintage motorcycles involves inherent physical risks; cross-check these factory baseline specifications against the condition of the actual machine and follow standard workshop safety practices, especially when servicing brakes, fuel, ignition, and rotating drivetrain parts.

A Preview of Pump-Stroke and Piston-Ring Inspection Data

For Autolube inspection, the manual specifies a minimum pump stroke of 0.20–0.25 mm with the throttle fully closed.

Piston-ring inspection data distinguishes end gaps measured with the ring square in the cylinder: 0.15–0.35 mm for DS7/RD250, 0.30–0.50 mm for R5C, and 0.20–0.40 mm for RD350.