evo ignition

[rittchie66]

im looking to change my stock evo ign with aftermarket and want to eliminate the vacuum switch...any ideas or recommendations ? thanks

[hdbikedoc]

   keep the voes its a good unit ,unless you are racing most aftermarket still use it

[Tomo]

Hi, maybe you could help me ? I'm a bit confused as to the actual purpose of the voes switch. It is not simply an advance /retard mechanism as a lot of people think. It seems it actually stops the ignition retarding if there is no load on the engine, ie at tickover or light running at low revs.  I strongly suspect the real purpose of this may be emission/ temperature control and nothing to do with "improved driveability" which is what is stated in the company blurb. My evo has been running happily for years with no voes fitted ( which is given as an option with the Crane Hi 4 set up.) The timing is controlled by built in adjustable advance curves which retard the ignition at lower revs whether or not the engine is under load, exactly as the old points system used to do. I have not noticed any lack of driveability as a result and would be very interested to hear some other views on this.

Tomo

[JamesButler]

im looking to change my stock evo ign with aftermarket and want to eliminate the vacuum switch...any ideas or recommendations ? thanks

The Dynatek 2000i ignition offers an assortment of ignition combinations. Choice of four curves with or without VOES, single or dual fire and rev. limit options.  If you have a modified stock EVO, their reps  suggest using the VOES.

[JBarrettB]

The stock ignition is a dual curve unit. It has an advance curve and a retard curve or economy and power curves if you like. The VOES determines which curve you are running depending upon the vacuum signal it receives and the threshold it is set at. The higher the setting the sooner you drop into the power curve and the longer you stay in it. Those settings vary depending what you have and what you are wanting it to do. Factory vacuum switch's range 4.0-5.5inHg.

A majority of the EVO's I see these days have switches that have failed, they will no longer hold vacuum, or the screw that sets the threshold has backed off and the switch is functioning at 1.5 in Hg. This has a major effect on the way the bike runs.

Nothing wrong with a stock ignition for a mild EVO build.

JB 

[ClassicRider2002]

The stock ignition is a dual curve unit. It has an advance curve and a retard curve or economy and power curves if you like. The VOES determines which curve you are running depending upon the vacuum signal it receives and the threshold it is set at. The higher the setting the sooner you drop into the power curve and the longer you stay in it. Those settings vary depending what you have and what you are wanting it to do. Factory vacuum switch's range 4.0-5.5inHg.

A majority of the EVO's I see these days have switches that have failed, they will no longer hold vacuum, or the screw that sets the threshold has backed off and the switch is functioning at 1.5 in Hg. This has a major effect on the way the bike runs.

Nothing wrong with a stock ignition for a mild EVO build.

JB

That was a great description you offered, and it's interesting that you see so many VOES that have failed or are not working properly.
That has been a issue for many justifying their removal.

Here are a couple of further reads for the original poster if he is so inclined:

CLICK HERE: 101 Harley-Davidson Evolution Performance Projects, Pages 208-210, 213

CLICK HERE

These brief descriptions also seem to offer at least some clarity on the merits of the VOES.

Regards,

"Classic"

[Tomo]

The stock ignition is a dual curve unit. It has an advance curve and a retard curve or economy and power curves if you like. The VOES determines which curve you are running depending upon the vacuum signal it receives and the threshold it is set at. The higher the setting the sooner you drop into the power curve and the longer you stay in it. Those settings vary depending what you have and what you are wanting it to do. Factory vacuum switch's range 4.0-5.5inHg.

A majority of the EVO's I see these days have switches that have failed, they will no longer hold vacuum, or the screw that sets the threshold has backed off and the switch is functioning at 1.5 in Hg. This has a major effect on the way the bike runs.

Nothing wrong with a stock ignition for a mild EVO build.

Ok ,so I'm hearing how it works,but I still don't know what its purpose is. It obviously dodges between the two curves depending on the ammount of vacuum it detects. This will in effect leave the timing advanced for Idle and low revs ( at light loads,) whilst retarding the timing when big welly is applied. Now if this is all about economy and emissions I might be inclined to continue to live without it.  However, there is another possibility, it could, be about temperature. Engines running retarded generate more heat and my Evo with no voes will be running retarded at low revs governed by the advance curve alone. I have to say it does get extremely hot if asked to tick over for any length of time and I usually have to switch off if I'm in that situation.  So to voes or not, that is the question !?

Anyone have two penneth to chuck in here ?
Tomo

JB

[badcooky]

S&S IST is the most advanced ignition out there mate.

[JBarrettB]

Tomo
The voes is the advance mechanism. Without the vacuum switch you have to decide which curve you want to run. advance or retard. By grounding the voes violet/white wire you choose retard(20deg BTDC). Ungrounded advanced(35deg BTDC). Assuming the timing is set according to the book. Neither curve is sufficient for all situations. Whether mechanical, manual, or electronic all engines need to vary timing to not only function efficiently but also to not blow the topend off.   
In short the voes allows the ignition to deal with the varying load requirement. It is simply an on/off switch, yes or no.

JB   

The above statement is incorrect in the following way. When the VOES violet/white wire is grounded the ignition is advanced(35deg BTDC) and then retarded when ungrounded. Sorry for any confusion here.

JB

[TheSwede]

Hi Guys,, The VOES is overrated,, it is an EPA demand,

remember every dynorun is without  VOES  (low curve)

Myself have a flip switch instead,, so I can chose high or low curve

and by experience I can say there is no noticeable difference.

Beast Regards
The Swede

[ClassicRider2002]

JBarrettB,

Could you ever in your mind justify or count it as reasonable, the changing of a VOES Switch from a 4 in Hg to a 5.5 in Hg within a application of running a 99 FXR (565 lbs) that is running a FXRP Ignition Module and has a collection of parts producing close to 84 HP and 94 HP which is built around more of the idea of a torque engine as opposed to perhaps a horsepower engine?

With the current specifics of the build the bike has had some slight engine rattle/pinging under WOT load conditions, from right around the 3000 - 3400 RPM about 400 RPMS on spring days 65-70 degrees and perhaps ranging anywhere from 3000 - 4500 RPMS on days into the heat of the summer.  The bike is primarily operated at 5,000 feet.  Under a recent test when 100 No Lead Octane  was placed into the bike, the symptoms disappeared under all load tests and speed tests that bike was put through, under temperatures of above 85 degrees.

Nothing has been done at all with the ignition timing, beyond the application of inserting a new 1994 FXRP Ignition Module. I have been running the OEM original 4 in Hg VOES Switch but as you have pointed out whether it's even functioning or functioning properly at this time is information I can not provide.  I plan to have it tested shortly by taking it to a dealer and getting a verdict.

Ultimate goal is to have the proper ignition advance for our mild-hopped-up evo-builds, which will help yield the best power numbers. 

1. We do not know exactly what that advance curve is with an FXRP Ignition Module, but we know that is has to be a less advance (less aggressive, smaller curve) than the stock curve.  We do not know the stock curve anymore because the MoCo has been kind of secretive about it.  We speculate it has changed for the worse over the years due to ever changing emissions requirements and regulations. 

2.  We know we can adjust our ignition curve by turning the cam sensor plate clockwise to advance and counter-clockwise to retard.  Thus, we know we need to retard our stock curve, i.e., turn it counter-clockwise, as we know we need less timing advance BTDC.  We do not know exactly how much to dial it back, as we are unsure of the hash-mark values (somewhere between 1.25 and 2.5º) on our Cam Position Sensor Plates.  It is not imperative that we know the curve exactly, but we can pinpoint the best curve on a DYNO through trial and error, "least-timing best-torque" method.  We know that our engines will run cooler with the proper advance, as the fuel-burn will be longer and slower.

3a. We know that the VOES controls the ignition advance curve by switching to either retard or advance mode based on the vacuum resulting in load at specific rpm.  Moreover, we know that heavier bikes require higher vacuum levels to avoid pinging. We know that the VOES was erratic in its early stages, but it is also "easily" adjusted to a specific vacuum level. Thus we speculate that maybe the 5.5" vacuum VOES will be better for our FXR's than the stock 4.0" because as you have mentioned "the higher the setting (of the VOES) the sooner you drop into the power curve and the longer you stay in it.  But, those settings vary depending what you have and what you are wanting it to do".
              3b.  We know that bigger engines need higher level of VOES, but that race engines do not use VOES.

4. The questions I have concerns adjusting the cam sensor plate and/or the VOES.  Do they both need to be adjusted or will adjusting one or the other independently, get us to our goal? Or do we simply find the least-timing best-torque (retarding the cam sensor plate) and just switch to the 5.5" level VOES?
     
I realize the jetting may have been weak, and has been some what responsible for current above description, but from an ignition timing stand point:

Knowing what you grasp about the purposes and reasons for the VOES Switch and it's roll in telling the ECM to switch from a Advance setting to a retard setting or visa versa, can you logically see any benefits from inserting a 4.0 in Hg vs inserting a 5.5 in Hg VOES Switch?

Good idea?
Bad idea?

Positives/negatives/

Could you talk about this a bit.

Regard,

"Classic"

[ClassicRider2002]

Hi Guys,, The VOES is overrated,, it is an EPA demand,

remember every dynorun is without  VOES  (low curve)

Myself have a flip switch instead,, so I can chose high or low curve

and by experience I can say there is no noticeable difference.

Beast Regards
The Swede

Swede,

Seems like JB's explanation above might counter that position, of course I am talking about running a HD OEM/or FXRP ignition module (I grasp that anyone running a aftermarket Ignition Module has options built into such that do not necessarily require the renderings of running a VOES Switch at all), thus connecting to the VOES would be important or in fact you are always going to be in a "retarding" mode since the switch would always be defaulted to off?

Could you explain a bit more please?

Regards,

"Classic"

[Tomo]

 JB,
There seems to me to be no reason why one curve should not suffice to alter your timing from advance to retard. Consider the old points systems, the more revs at the crank the more the little weights flew out- the more advance was applied. As the revs were reduced the little weights dropped back and the timing was retarded. Simples ! Note that with this system the timing is retarded at low revs regardless of load.

The voes however brings in an extra complication in that it distinguishes between heavy and light loads on the engine. Therefore when the engine is idling under light load or running light at low revs the retard curve will not be selected. This the reason for the two curves.

Now why is it an advantage to not retard the ignition if the engine is running light ? Is it economy ? Is it emissions ? Or is it Temperature ? I think most likely it is the latter. Air cooled engines running with retarded ignition at idle heat up very quickly. it doesn't take long before significant temperatures are reached and damage is likely to occur in the engine. So in my opinion the purpose of this rather complicated device is to keep the motor running cooler in situations of extended idling and slow running.

I rest my case.

Tomo

[JBarrettB]

Tomo and The Swede,

I'm out of breath...want to race?

JB

I will add. The only thing consistent in how an engine functions is the time it takes for the charge to burn.
That is the main reason for variable timing. At slow engine speeds the timing must be closer to TDC, while at red line if you want optimum power produced, you had better set off the burn sooner.   

[Tomo]

 

[smittyon66]

Tomo and The Swede,

I'm out of breath...want to race?

JB

I will add. The only thing consistent in how an engine functions is the time it takes for the charge to burn.
That is the main reason for variable timing. At slow engine speeds the timing must be closer to TDC, while at red line if you want optimum power produced, you had better set off the burn sooner.   

I agree about the need for variable timing. I'll also try to explain everything a little more using the specs for my 86 FXR as an example.

The ign module has 2 curves. if your static timing is correct at TDC, the slower curve starts there and ends at 35 BTDC at 2800 rpm. The faster curve starts at TDC and ends at 35 BTDC at 1800 rpm. Total advance is still the same, the difference is how soon the engine gets to total advance.

The VOES is simply an off-on vacuum switch and the different vacuum setting determine when the switch opens. With no vacuum, the switch is closed. If you go to a higher vac setting VOES, it will just hold the ign module in the slower curve longer and drop it back into the slower curve sooner under hard acceleration (low vacuum).

Low vacuum, the switch is closed, the wire from the ign module is grounded, and total advance is not achieved until 2800rpm. The purpose of this is to reduce pinging and detonation under low rpm, low vacuum situations like hard acceleration and heavy load.

You want to test a VOES? Just hook an ohm meter across the wires and use a mityvac to see at what vacuum the switch opens. Simple as that. As a matter of fact, you can remove the seal and adjust the hidden screw in the center of the VOES to set the vacuum setting to whatever you want.

If you rotate the timing plate and you will change the initial advance and total advance but not the shape of the timing curve.
If I move my 86 up to 4 BTDC initial advance, my total advance will be 39 BTDC at 2800rpm with the VOES switch closed.

Above 3000 rpm the VOES is just a paperweight that's along for the ride. The engine is already at total advance and the VOES has no effect on the engine at higher RPMs.

Race engines don't use a VOES because they simply don't need one. They aren't shifting until near redline. They don't roll on the throttle at 2000 rpm and try to accelerate without downshifting. They don't ride bikes in real highway conditions.
We might hotrod the hell out of these bikes, but we are nowhere near real racing conditions.

[Tomo]

Well, There goes my theory, off to hell in a handcart !! So there are no separate advance and retard curves on standard ignition modules just two different ramps. Secondly you're saying that heavy loads and big throttle openings give LOW vacuum ?? I was thinking the opposite and I'm gonna need some help with that. If thats the case then light loads and small throttle openings give HIGH vacuum ? How does that work ?
Of course I recognise the need for variable timing and you still get that with a choice of 5 advance curves on the Crane Hi4 set up. Without the vose you are obviously stuck with one curve and the idea as I see it is to choose the steepest ramp that doesn't give pinking on hard acceleration and load, and this will give you the best performance. In fact I've been running mine on the softest ramp ( No 1) curve with no vose which seems to give very pleasing results.

Despite the fact that my understanding of the workings of this mysterious little gadget appear to have been way off the mark, may I say this has so far been the most interesting forum thread I have ever seen and I feel I have learnt a lot already. Thanks to everyone who has contributed. Now, about this bloody vacuum ?

Tomo

[Old Crow]

Tomo, look at it this way.  The engine needs a certain amount of air to run.  If the throttle is closed or just barely open, you're sucking said air through the idle passages or a small portion of the venturi...high vacuum.  If the throttle is wide open, the hole you're sucking through is bigger...lower vacuum. 
Kinda like a water hose.  Open hose, water just kinda dribbles.  Put your thumb over the end of the hose and you can chase the dog across the yard with the stream.

[JBarrettB]

Well, There goes my theory, off to hell in a handcart !! So there are no separate advance and retard curves on standard ignition modules just two different ramps. Secondly you're saying that heavy loads and big throttle openings give LOW vacuum ?? I was thinking the opposite and I'm gonna need some help with that. If thats the case then light loads and small throttle openings give HIGH vacuum ? How does that work ?
Of course I recognise the need for variable timing and you still get that with a choice of 5 advance curves on the Crane Hi4 set up. Without the vose you are obviously stuck with one curve and the idea as I see it is to choose the steepest ramp that doesn't give pinking on hard acceleration and load, and this will give you the best performance. In fact I've been running mine on the softest ramp ( No 1) curve with no vose which seems to give very pleasing results.

Despite the fact that my understanding of the workings of this mysterious little gadget appear to have been way off the mark, may I say this has so far been the most interesting forum thread I have ever seen and I feel I have learnt a lot already. Thanks to everyone who has contributed. Now, about this bloody vacuum ?

Tomo

Glad you tossed the blinders. 

JB

[Tomo]

Tomo, look at it this way.  The engine needs a certain amount of air to run.  If the throttle is closed or just barely open, you're sucking said air through the idle passages or a small portion of the venturi...high vacuum.  If the throttle is wide open, the hole you're sucking through is bigger...lower vacuum. 
Kinda like a water hose.  Open hose, water just kinda dribbles.  Put your thumb over the end of the hose and you can chase the dog across the yard with the stream.

Thanks Crow, Thats a good analogy, I don't think I'll be taking up electro vacuum ignition system design any time soon, but this stuff is useful to know and I guess we've got the sucker taped now ! I think I'm in a better position to make a decision for or agin the voes, which seems to have developed mythical status in some quarters and is understood properly by very few people,it seems to me,( either side of the pond.) Anyone following this thread must surely be better informed about the thing, despite my ill informed attempts to cloud the issue ! Seems I need to re examine my overheating problem as well !  Good thread, thanks for input.

[ClassicRider2002]

The VOES is simply an off-on vacuum switch and the different vacuum setting determine when the switch opens. With no vacuum, the switch is closed. If you go to a higher vac setting VOES, it will just hold the ign module in the slower curve longer and drop it back into the slower curve sooner under hard acceleration (low vacuum).

Low vacuum, the switch is closed, the wire from the ign module is grounded, and total advance is not achieved until 2800rpm. The purpose of this is to reduce pinging and detonation under low rpm, low vacuum situations like hard acceleration and heavy load.

Above 3000 rpm the VOES is just a paperweight that's along for the ride. The engine is already at total advance and the VOES has no effect on the engine at higher RPMs.   

Smittyon66~

I appreciate both you and JBarrettB offering some very simple clarification issues on VOES and timing in general.  There just isn't that much discussion about timing for the EVO engines anymore.  A lot of this stuff was done in garages back in the day by trial and error, and I assure you others will benefit from this THREAD.

I have a quick question, in your statement above, that the "...VOES is just a paperweight.." above 3000 RPMS, I need some clarification, would it be correct to understand that at 3100 RPMS and cruising down the highway in 5th gear while I am going 70 MPH (3.360 Final Gearing) on my FXR2, at which point the VOES is in the advance mode since I am "not pulling on the throttle hard to maintain that particular speed however, if I decided at that point to WOT, the VOES Switch is then turned to the off position and goes into the "retard" map to accommodate my WOT needs......thus isn't there activity going on, so I am lost a bit by what you mean when you describe the VOES Switch as simply a "...paper weight..." above 3000 RPMS.  It would seem to me that the VOEWS switch is constantly moving on or off depending upon your throttle requirements. 

So what you are saying is that above 3,000 RPMS THE VOES is "literarily" a "paper weight" because by this point, no matter what you do with the throttle position of 10%, 20%, 30%, 50% 70% or 100% WOT, the VOES switch is in the "on" mode which will direct the ECM to "advance" the curve"? and that is how it's going to be?  ....because:
Above 3000 rpm the VOES is just a paperweight that's along for the ride. The engine is already at total advance and the VOES has no effect on the engine at higher RPMs.

Perhaps I am missing the "metaphor" here, i.e.: "...just a paper weight..."

Previously as stated above in one of the articles I provided this tip was offered:
"....Here's a tip: If you get intermittent pinging on acceleration, and if switching to better gas doesn't help, try recalibrating your VOES to retard the timing at a higher vacuum number before you start going crazy doing other, expensive, stuff....."

I guess I thought the VOES was playing a role at WOT roll ons regardless of your RPM range at the moment you begin opening the throttle up and the switch senses a change in load?

Can you expand on this please....Thank you.

Regards,

"Classic"

[badcooky]

 Yep Mighty Mouth is right here.
But he goes on and on and on  .

[ClassicRider2002]

The VOES is simply an off-on vacuum switch and the different vacuum setting determine when the switch opens. With no vacuum, the switch is closed. If you go to a higher vac setting VOES, it will just hold the ign module in the slower curve longer and drop it back into the slower curve sooner under hard acceleration (low vacuum).

Low vacuum, the switch is closed, the wire from the ign module is grounded, and total advance is not achieved until 2800rpm. The purpose of this is to reduce pinging and detonation under low rpm, low vacuum situations like hard acceleration and heavy load.

Above 3000 rpm the VOES is just a paperweight that's along for the ride. The engine is already at total advance and the VOES has no effect on the engine at higher RPMs.   

I will let my previous questions stand as I just mentioned, however as I reread your comment here several times:
"...The engine is already at total advance and the VOES has no effect on the engine at higher RPMS....."

If so, then any intermittent or continuous pinging under load one might have in a WOT position in 5th gear at 3000 RPMS or +++ would then not be looking at ignition timing to remedy, as it would only be a FUEL management remedy?

Or is there still some play that exists within the ignition timing under this example? 

If you were having the above issue, would you some how try to change the timing via the Cam Position Sensor by perhaps retarding it some to take out that "intermittent pinging" issue as expressed in the above example?

Regards,

"Classic"

[badcooky]

And on.

[jclark311]

Im using a Daytona Twin Tech, but I have also used the Ultima and it was just as good, but way cheaper.