Setting Ignition Timing on your
Harley-Davidson engine

Check ignition timing:

At every 5000 mile (8000 km) service interval. Check for proper RPM and ignition timing as follows:

1. See Figure 0. Thread TIMING MARK VIEW PLUG (Part No. HD 96295-65D) into timing inspection hole. Be sure view plug does not touch flywheel.

1a. See Figure 1. Locate the proper timing marks for your engine. If the shop manual is not available, remove spark plugs, turn engine until front piston is at TDC on compression stroke and identify TDC mark on the flywheel.

2. Connect leads of INDUCTIVE TIMING LIGHT to front spark plug cable, to battery positive terminal and to ground.

3. Be sure vacuum hose is properly installed at carburetor and at vacuum-operated electric switch (V.O.E.S.).

4. Start engine. Set engine speed by turning idle adjustment screw clockwise to increase speed or counterclockwise to decrease speed.

a. On world models, idle speed is 950-1050 RPM.

b. On California models, idle speed is 1150-1250 RPM.

5. Timing light will flash each time ignition spark occurs. Aim timing light into timing inspection hole. Front cylinder advance timing mark should be centered in timing inspection hole. If not, see ADJUSTMENT below.

6. Set engine slow idle speed as described in Step 4 with engine running at normal operating temperature and with enrichener control knob pushed in fully.

NOTE

Be sure the engine is warmed up to normal operating temperature and the enrichener knob is pushed all the way in before adjusting engine idle speed. Be aware that, because there are variations in individual components, it is possible for a properly warmed-up engine to idle at 2000 RPM with the enrichener knob pulled out partially.

1. See Figure 4. Remove outer cover pop rivets (1), outer timer cover (2), inner cover screws (3), inner cover (4) and gasket (5).

2. Loosen timer plate studs (6) just enough to allow sensor assembly (8) to be rotated using a screwdriver in the plate’s notch.

3. With timing light aimed into inspection hole, rotate sensor assembly (8) until front cylinder advance timing mark is centered in timing inspection hole.

4. Tighten timer plate studs (6).

5. Install gasket (5), inner cover (4), inner cover screws (3), timer cover (2) and new outer cover rivets (1).

6. Remove TIMING MARK VIEW PLUG from timing inspection hole. Install hex socket timing plug.

Figure 0
Timing Plug Location

Figure 1
Big Twin Engine TIming Marks

Early Style includes most 1980 and earlier models
Late Style includes most 1981-95 models

Figure 1a
Sportster Timing Mark

Figure 4
Ignition Timing