HarleyTechTalk

I was re-reading Pilgims VOES write up.  Esp the part about larger motors & baggers needing
the VOES to be adjusted for a higher vaccuum level to reduce pinging/detonation.  I'm thinking about doing this, but figured I'd ask you experts before I pull my tank off and
spend some nice spring-time doing this.

http://www.wildwestcycle.com/f_voes.html

Has anyone adjusted their VOES and made things better ?     

(fyi.. I have the Crane Hi4E in my 89 inch stroker )

thx
rdkng     

   Yes, I adjusted mine to 5.5 inches using a myty vac and it cured my detonation problem going up hill with a full load.
96 low rider, 50 thou off heads, cam etc.
Ron

Yes I, too, have used a Mityvac for adusting the VOES; works great.

If you would rather buy one set at 7 hg:


http://www.daytona-twintec.com/model_1005.html

VOES-KIT-MC7 VOES Kit (vacuum switch with higher switching level of 6-7 In-Hg vacuum helps eliminate spark knock under light load and throttle roll-on. Includes mounting bracket and electrical terminals. ARB E.O. No. D-641-3) $44.50

Jireh sells them in 1 hg increments, for around 25.00,

I used a green LED when installing mine per the old instructions. Green light comes on when throttle is closed or vacuum is high. Does this sound correct when used in conjunction with the DYNA2000/ S.E. programmable module?

I didn't use no fancy mity-vac to adjust mine. I adjusted it so it's on at idle (1,000rpm), and off at 800.

Quote from: rdkng on April 22, 2009, 07:12:49 AM
before I pull my tank off and
spend some nice spring-time doing this.

Rdking, are you sure you have to remove the tank?  Some models you can get it out without removing the tank?  Either way, with a mighty-vac and a continuity tester it's not tuff.  I set mine to 6.5" hg.  Bike is an fxst,  97", 9.5:1.

Correct me , if I'm wrong ......
Pinging ( detonation ) occurs when there's too much pre-ignition in combination with a certain amount RPM.
When you disconnect the VOES ( and plug the hose ) , without re-adjusting the ignition-timing , the Harley gets more sensitive for pinging , because it has always too much pre-ingnition now.
The highest vacuüm occurs with a closed throttle ( low rpm ) in the beginning of the power-band,....so the VOES is closed at that time , and gives a signal for LESS pre-ignition , which is nescessary for that moment of highest torque when needed
As soon the throttle goes more open ,...the less vacuüm it can build up behind the throttle valve , so the voes opens and gives MORE pre-ignition .
I took the "Potty mouth" thing out ,...and re-adjusted the timing for a little less pre-ignition , and mounted 1 grade colder sparkplugs in the engine . NGK  BPR6ES-11 .
Since then ,...No detonation anymore,  and a super steady idling.

George ,
Holland.

Thanks Bros, I apprecite the info.  I did use my mityvac and tested mine
when I was putting the motor together.  I think I was around 5 inches,
but not sure.  I'm VERY glad to hear this has helped with detonation.
(& I need to pull the tank anyway to check a couple things.. which isnt
bad since I added a quick disconnect.)    Guess I'll set it aound 6 and
see what happens..
Thanks!
rdkng   

QuoteCorrect me , if I'm wrong ......Huh?

You're wrong, on just about everything.

oke ,..so it's wrong ,.....

can you explain to me what's wrong ,...i'm certainly not too old to learn from you 

Guys,

Please let me ask a question without hijacking the thread. My engine (93 FXR), has been modified and has an adjustable ignition. There is a slight hiccup in the Dyno curve and on the road that you can feel when the Voes tries to retard the ignition timing. I have no pinging at 10.5 to 1 and the bike runs fine. The problem is in order to make any adjustments, the fuel tank, coil, top engine mount and stabilizer have to be removed to access the stock Voes switch. Looking for suggestions here, is there anyway to make an adjustment at one time? I have access to all the tools needed to do this job.

Buddy i set mine at 6.5 on my 113. All is good so far

The job for the voes switch is to retard the timing when there is any substantial load on the engine.
When there is a load on the engine the vacume drops and the voes switch retards the timing to prevent detonation,pinging,preingnition call it what you want.
Harley engines will idle better with more timing and at cruising speeds harley motors will run smoother(less vibration) with more timing,but as soon as you accelerate with the timing set to give you smooth idle and cruising, the motor will ping, so the voes switch kicks in and retards the timing.
With big inch motors you raise the vacume numbers on the voes switch because those motors do not lose as much vacume at partial throttle as smaller motors and a stock setting voes switch may not kick in and retard the timing.
Think of the voes switch as working backwards of your old smallblock chev distributor witch would advance the timing on acceleration.
If the voes switch fails or you disconnect it the timing will be retarded all the time. Its designed to do that so that if it does fail you wont burn the engine up or detonate it apart,just your bike wont idle as smooth or run as smooth when cruising.
Hope this helps
                                                          2High

The VOES is an on-off switch which is normally off, higher vacuum than whatever it is set at will switch it on which will close the circuit for the ignition, allowing the ignition reference signal to go to ground .  You can hook up a ohm meter and read between the two wires going to the VOES and they will be open, no current can flow. If you hook up a vacuum pump and increase the vacuum to the point where the switch is set you can hear it click and see the the ohm meter change state indicating that current is flowing - whenever the current is flowing the ignition will advance. The ignition module  sees the signal go to ground and advances the ignition, there are 2 ignition curves, one with the switch closed and one with it opened. When the VOES switch is open it uses the lower advance curve, the timing is not advanced as quickly. In the case with Ultima engines they recommend you set up the ignition to use a VOES but not to hook it up, they want to use the lower/slower  advance curve to help prevent detonation. More often than not if a VOES switch goes bad it will go bad in the off position, the timing will not be as advanced. It is a subtle difference, the VOES causes the ignition module to advance the timing when the vacuum is high and allows the timing to fall back when the vacuum is low, it does not hold back or retard the timing and you would not want it to work that way because then if it broke the timing would default to being advanced and it is better to have the timing not advanced than advanced too much at the wrong time.

Buddy WMC, Just remove one half of the tank, cut that switch loose from the harness, hang it below the tank, and adjust it, when you are done you can move it back up. This way you can play with it, and get it the way you want, with your bike running.

oke ,....so far , so clear to me about the working-explaination.
But when I want to adjust the carburator so that the engine is very low idling ...
( I know ,...it's not that very good for the oil flow and crank-shaft bearings   , but I just like it that way ).
Suppose that the engine is idling now , and I give throttle suddenly,....as soon as it falls back to low rpm ,  it takes a little time for building up vacuum in that voes .
What happens then , is that the engine stalls , so that's the reason why I removed that VOES a couple of years ago.
Is there anyone here , who succeeded to adjust the engine for low idling without a VOES ?
( sorry for possible language faults )

sorry ,...I mean with a voes...

Quote from: rdkng on April 22, 2009, 07:12:49 AM
I was re-reading Pilgims VOES write up.  Esp the part about larger motors & baggers needing
the VOES to be adjusted for a higher vaccuum level to reduce pinging/detonation.       

I am far from an expert and still have more to learn than most have forgotten.

If you are having a problem with detonation without a VOES, it will only get worse adding a VOES. The VOES does not retard the timing, it advances the timing. When you raise the vacuum level switch it in effect keeps the VOES off longer so it does NOT advance the timing.  Pilgrims site is great and it is correct but he is describing how to adjust a VOES so it does not advance the timing which will reduce detonation, but you say you do not have a VOES hooked up and considering adding it to eliminate detonation, which is a backwards type of thinking.

Under normal conditions, you must fix the detonation problems before adding a VOES, not add a VOES to fix a detonation problem. If you read Pilgrims site, you also read about using a led to help you figure out if the VOES is causing the detonation, this is done so you know that if it is not the VOES , adjusting the VOES will not help. On the other hand if you have a working VOES setup and you have detonation caused by the VOES advancing the timing too soon, you can raise the vacuum level to prevent the VOES from advancing the timing sooner, which will help eliminate the detonation.

As I posted, Ultima recommends not to even use a VOES with their big inch engines, but you still set the ignition up to use the VOES. You tape off the wire from the ignition to the VOES so the ignition can never get the signal through the VOES switch  to advance the timing more, causing the ignition to follow the lower advance curve rather than advance quickly. The lower curve ( VOES but no signal to ground) may only reach full advance above 3500 rpms, whereas with the VOES allowing the signal to ground will tell the ignition to jump up to full advance as low as 2000 rpms - I am just throwing out numbers to give you an idea how it works. You lose a little throttle response and power at low rpms but it helps prevent detonation - with a big inch engine a little lost power at lower rpms is a fair trade off to prevent detonation.



ON EDIT: Sorry, I got the previous message,

Quote"What happens then , is that the engine stalls , so that's the reason why I removed that VOES a couple of years ago. "

confused with the original post and thought the original poster said he removed the VOES.

pajoe
If I go start my bike right now and disconnect the voes switch,will the idle raise or lower?

Quote from: jclark311 on April 23, 2009, 06:38:20 PM
Buddy WMC, Just remove one half of the tank, cut that switch loose from the harness, hang it below the tank, and adjust it, when you are done you can move it back up. This way you can play with it, and get it the way you want, with your bike running.

Mine's an FXLR one piece single cap tank, so can't do it your way thanks for the tip tho. Think I'll play with the setting once my transmission gets back from Baker.

2high:

When I was using  a VOES  with the idle set at 1000 rpms and disconnected the VOES the idle would drop,  it would stay running and worked pretty good, throttle response would not be as good and gas mileage dropped a little - but I could ride without even knowing the VOES was not working because the differences  really were not that much under normal riding conditions but I guess on a dyno it would show up more. I  hooked up a led between the VOES and ground ( must keep led polarity correct, negative lead closest to ground) so any time the VOES was allowing current to flow to ground the led would light up. I could look down at the led and know when the timing was being advanced by the VOES and when it was not, when the current was flowing ( timing on advanced curve) the led would be lit and when it was not the led would be out. On mine the led was lit most of the time but if I rolled on the throttle about 1/3 turn the led would go out and I knew the ignition was on the lower advance curve.

As I posted previously, I am far from any kind of expert and there are many here that have forgotten more than I will ever learn. I do have some experience with detonation and replacing/adjusting  the VOES - The one I adjusted to 7 hg did not hold up very long  so I purchased one set at 7 hg and it held up very well.

pajoe
so we are on the same page then,when you nail it, the timing will be retarded or on the lower curve(same thing)
So I will stand by my original post then.
                                                           2high

Here's what the manual from the Ultima ignition says about the VOES:

The green VOES/RTD LED lights when the violet wire is grounded. With the ignition in normal mode and the VOES connected, the green LED
will be on most of the time (engine vacuum present). In Retard Mode, the LED can be used to check operation of the retard controller. (See
RETARD MODE USING THE VOES WIRE below.)


• V.O.E.S. SWITCH (NOT RECOMMENDED ON ULTIMA ENGINES)
VOES switches sense partial throttle openings (high vacuum) and open throttle (low vacuum) conditions in the intake manifold. All late model
Harley-Davidson engines incorporate a Vacuum Operated Electric Switch (VOES) in the intake manifold to sense the engine load. During part
throttle operation when manifold vacuum is high (i.e., light engine load), the switch closes, grounding the violet wire and causing the timing to
advance more rapidly.
This improves gas mileage at cruising speeds and provides crisper part-throttle response while preventing detonation during heavy engine
loading. Over the last few years switches are being produced that activate at a higher manifold vacuum and are required on larger cubic inch
engines. If you use VOES switches on large cubic inch engines your manifold vacuum is much higher and will require a non stock type VOES
switch that activates at a higher vacuum. VOES switches should be used on Ultima Engines by experienced tuners only.


• RETARD MODE USING THE VOES WIRE
This mode provides a convenient ignition retard for nitrous or turbo equipped bikes. When switch 1 is ON, the violet wire acts as a retard
trigger. To use this function, the violet wire is connected to a switch or relay that will ground it at the desired time. The violet wire should not
be connected a VOES when set for retard mode.
When activated, timing will be limited to 25 degrees regardless which advance curve is selected. When the violet wire is not grounded, timing
will follow the quick version of the selected advance curve. The following chart indicates how much retard can be achieved:

                     Final Timing          Final Timing with
Curve#           for Curve              Retard Activated        Total Retard
   1               34 degrees               25 degrees               9 degrees
   2               34 degrees               25 degrees               9 degrees
   3               32 degrees               25 degrees               7 degrees
   4               29 degrees               25 degrees               4 degrees



BTW, I got a flyer from Jireh today and the Ultima modules are on sale for $99.95 right now through 4/30