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

• Coverage and document identity: A 113-page PDF for the 1972 Yamaha DS7 and R5C and 1973 RD250 and RD350, carrying Yamaha document code SVM-360-0800-20 on the cover.
• Engine repair procedures: Covers engine removal, cylinder and piston inspection, clutch service, crankcase splitting, crankshaft checks, and transmission, kick-starter, and shifter disassembly and assembly.
• Autolube and induction systems: Explains minimum pump-stroke inspection, pump and carburetor adjustment, oil-pump bleeding, the 5-port cylinder layout, and the Torque Induction seven-port reed-valve system.
• Chassis and brake work: Separates the drum-brake front-wheel arrangement from the RD350 fixed-caliper disc brake, with wheel, fork, swingarm, steering-head, master-cylinder, caliper, and brake-bleeding procedures.
• Electrical diagnosis: Provides charging-output checks, regulator resistance tests, rectifier diode testing, alternator winding and brush inspection, battery troubleshooting, breaker-point service, coil tests, and ignition-timing adjustment.
• Factory illustrations and reference data: Features model-specific porting diagrams, clutch and transmission section views, brake-system drawings, steering-head exploded views, charging schematics, cable-routing drawings, and separate R5C/DS7 and RD250/RD350 circuit diagrams.

This Yamaha factory Service Manual combines the DS7 and R5C publications originally printed in Japan in September 1972, then adds the material needed for the RD250 and RD350. 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

The manual does more than place four model names on one cover. It identifies the DS7/R5C five-speed and RD250/RD350 six-speed transmission layouts, gives separate reduction-ratio data, and distinguishes the DS7's VM26SC carburetors from the VM28SC units used on the other three models. Model-specific cylinder-porting drawings show the DS7, R5C, RD250, and RD350 arrangements rather than treating the engines as interchangeable. The R5C's larger bore, different primary ratio, and larger rear tire are also called out in the factory foreword.

Engine and Fuel-System Repair Coverage

For major engine repair, 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 work extends to clutch plate and spring checks, primary-drive service, horizontal crankcase separation, connecting-rod play and crankshaft runout, crankshaft seal positioning, transmission removal, shift-fork placement, and shifter adjustment. Named shop equipment includes the armature puller or shock puller, chain removal and clinching adapters, the 350 YR1 clutch-holding tool, Yamaha bearing-fitting and fork-holding tools, a dial-gauge adapter, Point Checker, and Electrotester.

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 sections cover float-valve and overflow diagnosis, passage cleaning, throttle-slide synchronization, idle adjustment, and separate factory jetting tables. Reed-valve inspection covers the valve, stopper, gasket, and fasteners, with replacement guidance when the assembly cannot seal or operate correctly.

Chassis, Brake, and Electrical Detail

For the DS7, R5C, and RD250, the front-wheel chapter covers the two-leading-shoe drum brake, rim runout, spoke tension, lining inspection, and drum condition. The RD350 receives a separate hydraulic brake section with caliper and master-cylinder disassembly, piston and seal inspection, pad and disc limits, reassembly, hose and pipe installation, and system bleeding. Wheel-bearing replacement, tire service, front-fork teardown and seal replacement, swingarm-bushing inspection, and steering-head ball-race service are also covered. The rear shock is a non-serviceable assembly; its section is limited to leakage diagnosis and replacement criteria rather than internal rebuilding.

Charging-system troubleshooting follows the battery, regulator, alternator, rectifier, and main-switch circuit, then isolates faults with voltage and resistance checks. Ignition coverage adds breaker-point wear and gap service, condenser testing, static and running ignition-coil tests, spark-plug diagnosis, and dial-gauge timing of both cylinders. Appendices supply 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.

The manual warns that incorrect clutch thrust-washer or bearing placement can let the clutch boss rub the primary driven gear, while wrong piston-ring or piston orientation can damage rings and cylinder surfaces. In the RD350 brake system, mineral oil or alcohol can swell the rubber cups and seals, and removed caliper bridge bolts are treated as replacement items.

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.