What does a VOES switch do?

The Vacuum Operated Electric Switch (V.O.E.S.) was standard equipment on all Evolution® engines and works in conjunction with most all late model electronic ignitions, both factory and aftermarket. It senses high and low manifold vacuum and signals the ignition to change its advance slope.

How does VOES work on Harley?

These letters stand for Vacuum Operated Electric Switch. This Harley VOES switch has a very important function on a Harley-Davidson. It senses vacuum behind the butterfly of the carburetor and advances or retards the ignition timing accordingly. The Harley VOES switch remains closed until vacuum is introduced.

What does a Harley ignition module do?

The module sends a signal to the ignition coil, which turns 12 volts into thousands of volts to make a hot spark. The ignition coil is connected to the spark plugs through spark plug wires, which are specially designed for their specific duty.

What is single fire ignition on Harley Davidson?

The single fire ignition uses separate coil windings and electronics to fire each spark plug independently. Spark firing occurs only on the compression stroke. Conversion of older carbureted Harley-Davidson® engines to single fire is highly recommended.

How do I set the static timing on my electronic ignition?

Turn the ignition key to the RUN position and return to the distributor. Turn the distributor body COUNTERCLOCKWISE until the test lamp turns OFF. Turn the distributor another 10 to 20 degrees COUNTERCLOCKWISE. Now SLOWLY turn the distributor body CLOCKWISE… SLOWLY.

Is my Harley single fire or dual fire?

With the exception of the new Twin-Cam 88 and late model Sportster 1200 engines, all carbureted Harley-Davidson® engines have been dual fire. A single coil winding with two high voltage output terminals fires the spark plugs on both cylinders simultaneously. Each plug is fired twice during each four stroke cycle.

What’s the difference between single fire and dual fire ignition?

The main advantage of dual fire systems is simplicity and low cost. The advantage of single fire systems are smoother engine operation and the elimination of the popping that sometimes occurs when long duration camshafts are used. There is no horsepower advantage with single fire ignition systems.

What does the voes switch do on a Harley Davidson?

This Harley VOES switch has a very important function on a Harley-Davidson. It senses vacuum behind the butterfly of the carburetor and advances or retards the ignition timing accordingly. The Harley VOES switch remains closed until vacuum is introduced. When closed, the timing is retarded.

How does the vacuum switch work on a Honda Voes?

The VOES unit is a normally open switch, meaning with low or no vacuum (start-up / moderate to heavy throttle) the switch is “off”. That is the position you want for starting, acceleration, and high-load operations. When vacuum increases (idle and light throttle) the switch turns “on”.

How do you hook up a Harley Voes to a meter?

Hook up your meter to the switch. The black lead will go to the black Harley VOES ground wire and the meter’s red lead will go to the wire that was plugged into the ignition’s violet wire. Secure a completely sealed vacuum line between the the Mighty Vac and the switch. Set your meter to ohms with audible.

Is the switching point on a Harley Davidson bike adjustable?

These switching points are measured in inches of mercury. While it’s not mentioned in the service manual, the Harley VOES is adjustable. If your bike is heavily modified, you may need to adjust your switching point to compensate for the new hp/weight ratio. Keep an eye out for another article on VOES adjustment later.