VOES = vacuum operated electronic switch, or something like that. It is activated by inlet vacuum, and sends a signal to the ignition module to retard timing on starting and accelerating. What brand of ignition module do you have?

 

As far as I know the bike is stock. And according to the manual, only bikes meant to be sold in California have that. The factory service manual takes about reed valves in the air filter housing, and shows images of them for California models. I just took apart mine on Sunday and it doesn't have anything like that. S&S says I should just cap off that port on the intake manifold. I guess I'll ask HD technical support...

 

I just checked my books (back to 1980). The reed valves have nothing to do with the Vacuum Operated Electric (VOE) switch. The reed valve was used with the charcoal canister used on all California models.

The VOE is used on all of the Harley V2 Electronic Control Modules (Electronic Ignition). It was not used on the first Electronic Ignition used by Harley. It was first used on all BT models starting in 1983. (Part number 26555-83 changed in '84 to 26555-84) The VOE controls the two MAP curves in the ECM. it is located between the cylinders and attached to the upper motor mount.

 

My 1990 FLHS had a VOES (I bought the bike new) and when I swapped to a Crane ignition I retained it. Ran like a bitch when the hose split! So depending on your current set-up it is in my experience an essential item! According to my parts book it is stock on all models from 1984 on.

 

I still can't find anything in the factory service manual that even remote refers to anything called "VOE" or "VOES". I can see the VOV in the diagrams, not nothing about a VOE or VOES. What page in the manual talks about this?

 

I don't know what "Factory" service manual you're looking but I have the Harley Davidson Factory Service Manual (99843-90) covering 1984-1990 FLT/FXR Models. The V.O.E.S. starts on page 8-3 with pictures. It talks about where it is located and how the ignition works and how to test it. Then on page 8-11 Titled "Vacuum Operated Electric switch (V.O.E.S.)". It covers how to test the switch. Then on page 8-12 is figure 8-4 showing the complete ignition component, including the V.O.E.S.

Are you sure you're looking in a Factory Harley manual, and not one of those "Pep Boys" books?

And I don't even see a "VOV" that you are talking about. What is that?

 

You are looking at a different service manual for a bike I don't own. I have the 84-98 Harley Davidson service manual for the FLH/FLT/FXR Evolution bikes. I own an 89 FLHS. I wouldn't go to Pep Boys if I were you. Too much Chinese crap.
VOV is Vacuum Operated Valve that is part of the emission control system on 1988-1991 California models.

 

You need the VOES to signal spark advance in your ignition module. The Ignition module uses RPM and manifold vacuum to determine spark advance. ie at Wide Open Throttle (WOT) you drop manifold vacuum and the system knows by the signal sent from the VOES (Vacuum Operated Electric Switch ie.Low Pressure Switch)and based on engine RPM the ignition module will decide if advance stays the same or changes. I suppose it would run without the VOES but seems to me your engine would be under powered and wasting fuel at WOT high RPM without the spark advance.

 

Well, that explains it. Thinking "intake manifold" I was looking at the fuel, exhaust and emissions chapter. Now that I see "ignition" I decided to look at the electrical chapter and sure enough, there it is, chapter 9, page 446. Never mind. This D-Oh! moment brought to you by...

 

You're on thin ice here old chap! You have a 1989 FLHS, virtually identical to my 1990 FLHS. Ultra and I have the same manual, which he gave you the reference to above, which is the correct book! If you can't find the page references he gave you, then the book you have isn't the same as ours. I suspect the book you have is a which is not factory!

Accept no substitutes......

The VOV you refer to is covered on page 4-47 and illustrated in fig 4-45.