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[Spiderman]

The Vaccum Operated Electrical Switch is the trigger mechanism for all Evolution style Harley-Davidson engines using V-Fire III style ignition. In brief it takes a vacuum reading from the intake and converts it into an electrical signal that is sent to the ignition module. The unit sits between the cylinders usally mounted to the underside of the motor mount or somewhere in the vicinity.

My question is when using aftermarket ignition systems and different carburetors than the stock units that came on Evos, what happens with this switch. I've built bikes ground up but always employed someone to wire and fire the bike when completed. The chopper I'm currently trying to finish - - - I don't have that option.  The wiring harnes we are using includes everything a stock 94 and up softail would have except anything for the VOES. Jerry and others - -  you want to take a crack at talking me through this please ?

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[Classic Beast]

The VOES is designed to advance the ignition under part throttle hi vacuum situations (cruise) on a stock motor this works great but on larger motors if you want to use it the setting will have to be adjusted otherwise it is on most of the time and contributes to pinging I found on my 110 and 127 they run better without it. See below chart that shows the advance range for different sizes of motors the larger motors don't tolerate as much advance.

Engine Displacement 80”    96”    100”   107”   113”   120”  127”   130”   140”
Total Timing       @ 32-34 32-34 30-32 30-32 30-32 25-28 25-28 24-26 24-26
Full Advance

[Spiderman]

Right out of the online tech manual

      NEXT!

[Twolanerider]

Brian, it'll depend on which aftermarket ignition system you're using.  Some had a mechanical advance built in to them.  If so the VOES switch became unnecessary.  Some, like the Crane HI-4 I used to like and use could swing either way.  Racers would use the ignition system without the VOES switch as they didn't want the advance and the issues that might come with it.  For street use, however, the same ignition system worked well with the VOES switch hooked up and the ignition kit included a place to (electrically) connect it.

Remember too that the VOES switch wasn't a "advance" akin to a vacuum advance we think of on old distributors in cars.  The VOES switch was just an on/off switch triggered by vacuum.  It's default was off; no advance.  Then when vacuum was good it switched "on" which sent an electrical signal to to the ignition system that switched that system to its other map.  The ignition system just switched back and forth between a more retarded base map and a more advanced secondary map depending on whether the VOES switch was turned on or not.  If the switch was bad or even missing altogether, however, the bike would still run.  It would just do so without the at least potential benefit the map with the more advanced timing map.

[Spiderman]

Compu-fire Ignition and voltage regulator linked to a Del'Orto dual throat on a high compression 100" Evo motor.

[Twolanerider]

Compu-fire Ignition and voltage regulator linked to a Del'Orto dual throat on a high compression 100" Evo motor.

Below is a link I just stole from Compufire's website Brian.  It's an FAQ page with a section on VOES.

Short answer is, sure, you should mount a switch and wire it in.  Switch location is irrelevant.  You just need to get a vacuum line to it.  Use an ohm meter and a vacuum pump to adjust the VOES switch to best match the requirements of your engine/bike combination.

http://www.compufire.com/index.php?option=com_content&view=article&id=14&Itemid=32

[jclark3]

The factory mount for the voes is on the engine mount of a softail, but you are probably mounting your coil to the engine mount. I relocated my voes to a spot under my tank, with a tie wrap. I used the daytona twintec nose cone ignition, and their matching voes. Didnt really cost more

[Spiderman]

Below is a link I just stole from Compufire's website Brian.  It's an FAQ page with a section on VOES.

Short answer is, sure, you should mount a switch and wire it in.  Switch location is irrelevant.  You just need to get a vacuum line to it.  Use an ohm meter and a vacuum pump to adjust the VOES switch to best match the requirements of your engine/bike combination.

http://www.compufire.com/index.php?option=com_content&view=article&id=14&Itemid=32

Ok  I don't recall using the VOES on the Del'Orto before. Will have to see if there is a nipple for a vacuum line.  Thanks for the help amigo.
Any chance you're gonna get out this way ?

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