Yamaha YX600 Radian Service Manual Set 1986–1990 (P/N LIT-11616-05-06)

The supplements provide model-specific changes to use alongside the S/SC service procedures; they are not standalone overhaul manuals.

W/WC service requirement: Yamaha’s W/WC foreword also calls for a V/VC supplementary manual. The earlier supplement included here is labeled U/UC; a separately labeled V/VC supplement is not included.

PDF Bookmarks, Wiring Detail, and File Contents

Search and diagram navigation: PDF text search is not available. Embedded bookmarks organize the main chapters and both supplements, although the external “Back to Index” link requires a separate file. Small wire-color codes and connector labels in the checked wiring diagrams are readable when enlarged.

The ZIP contains one printable, English-language, 319-page PDF, including the separate YX600 (S-A) cover and all introductory and memo pages. The publication counts above account for 318 pages; the separate cover is already included in the total.

Engine Overhaul, Carburetor Service, and Electrical Fault Tracing

The following highlights are a selection of the included content, rather than a complete contents list. Other topics include throttle-cable adjustment and headlight-beam adjustment.

• Engine and transmission: Step-by-step engine removal, crankcase separation, crankshaft and connecting-rod inspection, oil-pump repair, clutch service, transmission inspection, and engine reinstallation.

• Valve train and tune-up: Valve-clearance measurement, adjusting-pad replacement and selection charts, cam-chain adjustment, cam timing, and compression testing.

• Carburetion: Mikuni BS30 carburetor removal, disassembly, cleaning, inspection, reassembly, float-height and fuel-level adjustment, and carburetor synchronization.

• Brakes and wheels: Wheel-bearing replacement, dual-disc front caliper and master-cylinder repair, hydraulic bleeding, rear drum inspection, and brake-shoe plate assembly.

• Suspension and final drive: Fork teardown and seal installation, steering-head bearing service, swingarm inspection and shim adjustment, shock inspection, and chain and sprocket replacement.

• Electrical systems: Starting-interlock, ignition, charging, lighting, signal, oil-level, and California air-vent troubleshooting, with separate S/SC, U/UC, and W/WC diagrams.

Yamaha wrote these manuals primarily for its dealers and qualified mechanics, assuming a basic understanding of motorcycle repair technology. They suit experienced mechanics who can interpret inspection results and use precision measuring equipment; they are not an introduction to motorcycle repair.

Engine Inspection and Reassembly

The engine chapter distinguishes work possible with the engine in the frame from full powerplant removal. It covers the air-cooled DOHC four’s cylinder head, valves, guides, seats, springs, pistons, rings, crankshaft, and connecting rods.

Inspection data address head warpage, camshaft wear, bearing clearances, oil-pump condition, gear engagement, and transmission-shaft runout. Crankcase and crankshaft identification marks are tied to bearing-selection information, allowing the mechanic to match replacement bearing grades to the measured assembly.

Assembly references: Exploded views, tightening sequences, lubrication callouts, sealant locations, and component-specific torque tables accompany upper and lower crankcase assembly, HY-VO primary-drive work, starter-drive inspection, and clutch installation.

Yamaha warns that crankcase sealant must be kept away from the oil-gallery O-ring and crankshaft bearings. Uneven cam-cap tightening can damage the head, caps, and camshaft; excessive camshaft rotation during installation can damage pistons and valves.

Valve Pads and Mikuni Carburetors

The valve-clearance section shows TDC indexing for each cylinder pair, use of the YM-01245 tappet adjusting tool, pad removal, and separate intake and exhaust pad-selection charts.

A labeled carburetor section view distinguishes the main metering, float, and starter systems. Inspection covers throttle diaphragms, needle valves, seats, and starter plungers. Float-height and fuel-level checks are treated separately, while the synchronization section identifies the YU-08030 vacuum gauge.

Chassis Repair and Service Tools

Component-level drawings identify the front-wheel speedometer drive, rear brake-shoe plate, caliper and master-cylinder parts, fork damper rod and bushings, steering bearings, and swingarm pivots. Rear shock coverage consists of removal, inspection, and replacement rather than internal rebuilding.

Fork procedures identify the YM-33298 cylinder holder and YM-33963/YM-08010 seal-driver weight and adapter. Brake sections explain seal inspection, bleeding, and rubber-component handling cautions.

Electrical Diagnosis and California Equipment

Starting-circuit troubleshooting distinguishes starter-motor faults from relay, diode, clutch-switch, neutral-switch, and sidestand-switch problems. Starter-motor repair includes brush, commutator, and armature inspection; charging diagnosis includes stator and field-coil tests.

Variant differences: The W/WC supplement supplies changed ignition, charging, and starter specifications. Its digital-ignition control diagram explains the single-pickup microprocessor system and the ignitor’s electric fuel-pump control.

The California carburetor air-vent section maps the canister, rollover valve, air-vent control valve, and hose connections. Its fault chart addresses an inoperative valve associated with loss of engine power.

The electrical starting-system circuit diagram, carburetor section view, intake and exhaust pad-selection charts, lubrication diagram, and cable-routing views provide references beyond the model-specific wiring diagrams. Electrical tool listings include the YU-33260 electro tester.

When performing engine, wheel, fork, fuel, battery, or brake work, secure the motorcycle as Yamaha specifies and observe the manual’s component-specific fire, electrolyte, and brake-fluid precautions.

Selected Carburetor Settings and Ignition Test Values

For the S/SC Mikuni BS30 carburetors, the float-height specification is 20.0 ± 1.0 mm, measured from the float-chamber mating surface with the gasket removed and without depressing the spring-loaded inlet needle. The separate fuel-level specification is 2.0 ± 0.5 mm below the carburetor body edge.

Ignition-coil primary resistance is 2.43–2.97 Ω at 20°C (68°F) for S/SC, compared with 1.8–2.2 Ω at the same temperature for W/WC. These are variant-specific test specifications.