How to Change Harley Points

Kevin rolled his ’77 Sportster on the lift to give us a quick demonstration for setting Harley points gap.
This ignition system has 2 circuits. The primary circuit consists of the battery, ignition switch, primary coil, Harley points and condenser.

The secondary circuit consists of the secondary coil, and spark plugs / spark plug wires.

The circuit breaker, or Halrey points, has 2 functions. The breaker cam and contact points open and close a low voltage circuit between the battery and the ignition coil. This causes the coil to produce a high voltage discharge to the spark plugs.

Secondly, the Harley points time the voltage discharge for correct ignition firing.

The breaker points are opened and closed by a cam that has one narrow lobe and one wide lobe. The narrow lobe times the front cylinder spark and the wide lobe times rear spark.

An advance assembly advances and retards timing mechanically as engine speed increases and decreases through the action of the fly-weights at the circuit breaker base. This is important for correct spark timing upon start up as well as low & high speed requirements.

Circuit breaker points gap should be inspected at every oil change or whenever performing routine maintenance.

To check or set Halrey points gap; start by removing spark plugs and shifting motorcycle into high gear.

Rotate the motor until the cam follower is at the highest point of the wide cam lobe. Check or set the gap with an .018″ feeler gauge. If the gap is incorrect, loosen the stationary contact plate and adjust as needed until .018″ gap is achieved.

The best way to move the contact plate is by gently twisting a flat blade screwdriver in the adjusting notch.
It is also important to check the Halrey points gap on the narrow lobe.

Points gap should be the same for both wide and narrow cam lobes.

If there is more than .004″ variation between lobes, it is an indication that the cam is not spinning true, or is running eccentric. This condition must be corrected prior to setting final points gap or starting the motorcycle.

More about Ironheads Here