1974–1976 Harley-Davidson SS/SX 175-250 Service Manual (P/N 99490-76)

• Coverage and document identity: A 126-page PDF of Harley-Davidson Service Manual P/N 99490-76, revised 12-75 and arranged in Product, Chassis, Engine, Transmission, Electrical, and Miscellaneous sections. The factory model table lists the 1974 SX-175; 1975 SX-175, SX-250, and SS-250; and 1976-and-later SS/SX-175 and SS/SX-250 models.
• Engine repair depth: Documents engine stripping, removal, and installation; cylinder and piston disassembly and inspection; 175/250 cylinder-piston color codes and clearance tables; crankcase splitting with or without the factory splitting tool; and crankshaft rebuilding, truing, installation, and end-play adjustment.
• Chassis procedures: Covers rear-chain service, front and rear wheel-hub work, steel and aluminum rear-hub configurations, brake-sprocket assemblies, wheel spoking and truing, and brake disassembly. Separate procedures address Marzocchi, Ceriani, and Betor forks, the steering head, rear suspension, and rear-fork pivot adjustment.
• Clutch and transmission work: Distinguishes the earlier and later clutch assemblies, with clutch diagnosis, disassembly, adjustment, inspection, and special-tool procedures. Starter and shifter service is followed by separate coverage of the bushing-type transmission used on the SX-175 and early SX-250 and the roller-bearing transmission used only on later SX-250 builds.
• Electrical diagnosis: Provides five build-specific wiring diagrams for the 1974/early-1975 Type A and late-1975 Type B/Type C handlebar-switch and key-switch combinations, plus 1976-and-later wiring. Alternator, ignition module, rectifier, ignition coil, battery, and ignition-light switch troubleshooting is included.
• Fuel, lubrication, and factory data: Details carburetor operation, adjustment, partial and complete disassembly, float-level checking, fuel-tank and supply-valve service, oil-pump adjustment/removal/bleeding, SS and SX muffler service, and alternate air-cleaner arrangements. Reference material covers torque specifications, capacities, wear limits, clearances, gear ratios, service charts, and system-specific test data.

Workshop Scope

This factory manual covers a single-cylinder, air-cooled, loop-scavenged two-cycle platform at a level that goes well beyond routine tune-up information. It is suitable for readers performing basic maintenance and repair, while Harley-Davidson directs its factory-approved major repair methods to professional mechanics. The foreword also points users to separate service bulletins for interim engineering changes and supplementary model information; this book is a service manual, not an illustrated parts catalog.

Build-Specific Information

Model differences are carried into the service data instead of being treated as one generic SS/SX specification. The Product section supplies separate 1975-and-earlier and 1976-and-later lubrication charts, sprocket and overall gear-ratio tables by model, and a VIN identification table with model-letter codes for the later machines. Cylinder and piston selection is split into SX-175 and SX-250 color-code tables, while the transmission chapter explains where the later SX-250 roller-bearing design replaces the bushing-type arrangement.

Oil pumps are build-specific as well. The manual states that the 175 cc and 250 cc pumps have different calibrations and identifies them by the displacement stamped on the control lever, helping prevent the wrong pump from being selected during repair.

Electrical coverage is similarly divided. The wiring sheets identify 1974/early-1975 Type A controls with the 71505-73P key switch; late-1975 Type B controls with either the 71505-73PA or 71505-75P switch; late-1975 Type C controls with the 71505-75P or 71514-75P switch; and the 1976-and-later layout. That breakdown matters when tracing faults or matching replacement switchgear to the motorcycle's build.

Repair Procedures, Tools, and Visual References

The engine chapters move from inspection and fitting data into major repair operations. They cover crankcase separation, crankshaft and connecting-rod work, crankshaft runout checks, reinstallation, and final end-play correction. Carburetor chapters explain starting, low-speed, and high-speed circuits before moving into cleaning, jet inspection, float gaging, and reassembly. The lubrication section adds oil-pump flow adjustment and bleeding rather than stopping at oil type and capacity.

Factory tool references are identified where they affect the work. Examples include the 95500-29A wheel truing stand, 97358-74P crankcase splitting tool, 96650-30 crankshaft truing stand, 97362-74P carburetor float gage, 97361-74P transmission assembling tool, and 97360-74P ignition timing setting tool.

Representative illustrations include the Marzocchi fork exploded view, crankcase-parts exploded view, carburetor cutaway, later SX-250 roller-bearing transmission exploded view, alternator-components exploded view, and the build-specific wiring diagrams. These sit alongside the clutch exploded view, starter cross-section, service charts, and adjustment drawings.

The manual also calls out repair traps that can create secondary damage. The right crankcase cover must come off evenly because damaged mating surfaces can cause oil leaks after assembly, and the thrust-collar end of a speedometer or tachometer cable must remain at the instrument end or it can damage the drive mechanism. Fuel-system work carries specific fire precautions: gasoline liquid and vapor must be kept away from smoking, open flame, and sparks, and the tank-repair section warns of explosion risk if fuel traces remain before flame repair.