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

This Harley-Davidson factory service manual (P/N 99490-76) includes revisions dated December 1975. Model coverage starts with the SX-175 for 1974, adds the SX-250 and SS-250 for 1975, and adds the SS-175 for 1976. The foreword directs readers to separate dealer service bulletins for interim engineering changes.

Reading the PDF and Wiring Diagrams

Text search and diagram detail: The PDF has no searchable text or embedded bookmarks. Small wire-color codes and terminal numbers in the wiring diagrams are readable when zoomed in.

The download contains one printable English PDF with 126 pages, including the one-page cover and 125 pages of front matter and service content.

Engine Overhaul, Chassis Service, and Electrical Diagnosis

This selection of service topics includes major repairs and routine checks. The manual also covers headlamp aiming and speedometer and tachometer drive cable service.

• Engine repair: Engine removal and installation, cylinder and piston inspection, crankcase separation, crankshaft rebuilding, truing, and end-play adjustment.

• Clutch and transmission: Early and later clutch designs, kick-starter service, shifter inspection, and mainshaft and countershaft disassembly, with transmission end-play and starter-clearance tables.

• Fuel and lubrication: Dellorto VHB27AD and PHB32AD carburetor service, float-level checks, throttle-cable adjustment, and automatic oil-pump adjustment, replacement, and bleeding.

• Chassis service: Wheel spoking and truing, hub repair, front-fork overhaul, steering-head adjustment, rear-suspension service, and mechanical drum-brake inspection and adjustment.

• Electrical diagnosis: Alternator, ignition module, rectifier, and ignition-coil troubleshooting, plus ignition timing, battery testing, and wiring diagrams for different switch configurations.

• Workshop references: Engine and chassis fastener torque tables in ft-lbs and kgm, the Wheel Service Chart, and Lubrication and Service Charts.

The manual guides readers through basic maintenance and repair. The foreword addresses its major repair methods to professional Harley-Davidson mechanics.

Cylinder, Crankcase, and Crankshaft Repair

Cylinder-piston color-code tables distinguish preferred and acceptable matches, and inspection tables separate assembly clearances from wear limits. These references help you select a cylinder-piston pair and assess wear before reassembly. The cylinder inspection section explains how a loose ring locating pin can let a ring catch in a port and damage the chrome-plated bore.

The crankcase section includes an exploded view and step-by-step separation procedures using tool 97358-74P or ordinary hand tools. Crankshaft overhaul covers press disassembly, flywheel alignment, truing, and thrust-washer selection.

Clutch and Gearbox Variants

Separate exploded views distinguish the bushing and roller-bearing transmissions. Gear-ratio tables accompany shaft and gear inspection, and the assembly section shows how to check gear engagement before closing the crankcase.

The clutch diagnosis chart lists possible causes of slipping and dragging. The later-clutch procedure covers plate replacement with tool 97354-74P while the clutch remains installed. A kick-starter cross-section shows the ratchet and release mechanism.

Forks, Wheels, and Rear Suspension

Marzocchi, Ceriani, and Betor fork procedures distinguish internal parts and wet versus dry oil quantities. Wheel service distinguishes steel and aluminum rear hubs and includes quick-detach rear-wheel removal.

Steering-head bearing service, the frame dimension drawing, and rear-fork pivot adjustment support chassis work. Rear shock coverage is limited to adjustment and replacement of the assemblies.

Carburetors, Oil Pump, and Exhaust

A carburetor cutaway shows the starting, low-speed, and high-speed circuits. Separate exploded views and service procedures explain differences between the two Dellorto builds, including their float-valve seat arrangements.

The oil-pump section explains the model-specific calibrations and shared throttle-cable equalizer. It covers external adjustment, bleeding, and replacement and warns that overtightening the mounting screws can distort the pump body and bind its internals.

Muffler service covers carbon removal and the SS and SX exhaust arrangements. The fuel-system section warns about gasoline-vapor ignition and reserves tank welding for qualified repairers.

Ignition Tests and Switch-Specific Wiring

The wiring diagrams distinguish Type A, B, and C handlebar switches and key-switch variants 71505-73P, 71505-73PA, 71505-75P, and 71514-75P. Matching the diagram to the installed switchgear lets you trace a fault against the correct terminal layout.

The no-spark procedure covers capacitor charging-coil, pickup-coil, and ignition-coil checks. Diagnosis of the sealed ignition module relies on substitution. Separate rectifier tests, charging-output checks, and battery load testing cover the charging system.

Bore, Assembly Clearance, and Charging Test Examples

The engine specifications list nominal bores of 61 mm for the 175 models and 72 mm for the 250 models. On the SX-175, piston-to-cylinder assembly clearance is 0.0006–0.0018 in., with piston diameter measured at its major diameter 0.87 in. (22 mm) above the bottom of the skirt. Connecting-rod end play between the flywheels is 0.012–0.016 in. (0.30–0.40 mm) at assembly.

For the battery charging test, the manual specifies a minimum alternator output of 4.6 A DC at 3,600 rpm with the headlamp on.