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  1. #1

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    Default VOES with a Lectron carburetor?

    I'm building a 1980 Ironhead (XLH 1000 if you wanna be technical). I've never built a bike from the ground up like this. It was a complete basket case when I bought it, with the exception being that the cases weren't split. Anyway, I recently acquired a Lectron carburetor for it and I'm wondering if I need to run a VOES with it. Anyone have any experience?

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    It depends on the ignition system you decide to use. Because the ironhead and shovelhead have large lazy combustion chambers, the electronic ignitions for those models used a fixed advance curve with no VOES. (Possible exception, the '85 XL.)

    Jim

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    Quote Originally Posted by JBinNC View Post
    It depends on the ignition system you decide to use. Because the ironhead and shovelhead have large lazy combustion chambers, the electronic ignitions for those models used a fixed advance curve with no VOES. (Possible exception, the '85 XL.)

    Jim
    Thanks for the reply. I'm considering using the Ultima single fire electronic ignition.

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    Checks the specs, but my Ultima has provision for VOES (Shovelhead) and I use one. Happy with it.

    It will have a dedicated wire, if so.. The diagram will tell you.

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    PS: A VOES is just a vacuum switch that retards the timing slightly under heavy load.

    It helps to avoid detonation.

    You should be running premium gas and I don't think the carb matters at all.

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    I have never had a bike with a VOES on it & have never fitted one, don't see the need for it myself,
    I'm running a new Lectron & a Morris Magneto anyway so no problems,.... just seems like something else to go wrong to me

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    Quote Originally Posted by confab View Post
    PS: A VOES is just a vacuum switch that retards the timing slightly under heavy load.

    It helps to avoid detonation.

    You should be running premium gas and I don't think the carb matters at all.
    Thanks for replying. And yeah I know what they are, I just don't really know how necessary they are. I didn't even think to look at the wiring diagram (seems kind of obvious now though haha)

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    Quote Originally Posted by tzienlee View Post
    I have never had a bike with a VOES on it & have never fitted one, don't see the need for it myself,
    I'm running a new Lectron & a Morris Magneto anyway so no problems,.... just seems like something else to go wrong to me
    I'm also considering getting a Morris Mag for mine. Not sure if it's worth the cost on an Ironhead though.. What's your bike?

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    mines a 78 Shovelhead,
    but have had Magneto's on all my Harleys since 77,except for two I was just turning round,...
    I like them & have NEVER had a problem with one, seems a few do but I put it down to ignorance & badly fitted units,
    Attached Thumbnails Attached Thumbnails zz222.jpg  

  10. #10

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    Quote Originally Posted by tzienlee View Post
    mines a 78 Shovelhead,
    but have had Magneto's on all my Harleys since 77,except for two I was just turning round,...
    I like them & have NEVER had a problem with one, seems a few do but I put it down to ignorance & badly fitted units,
    That's a sweet setup.

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    Quote Originally Posted by JudEl View Post
    I just don't really know how necessary they are.
    They really aren't.. It just lets you run a little more timing. Which can be problematic on an air cooled engine sometimes. Particularly if you aren't running good fuel or you aren't jetted right.

    It's not a huge deal if you want to omit it.

    It's a grounding switch.. So, it is easy enough to add later if you want.

    You can switch the VOES functionality off with the Ultima. Or at least on the shovel, anyway. Look for a dip switch on the front for VOES on/off.

    Last edited by confab; 05-05-2021 at 1:13 PM.

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    Quote Originally Posted by confab View Post
    They really aren't.. It just lets you run a little more timing. Which can be problematic on an air cooled engine sometimes. Particularly if you aren't running good fuel or you aren't jetted right.

    It's not a huge deal if you want to omit it.

    It's a grounding switch.. So, it is easy enough to add later if you want.

    You can switch the VOES functionality off with the Ultima. Or at least on the shovel, anyway. Look for a dip switch on the front for VOES on/off.

    Fortunately, with the Lectron, I won't have to worry about improper jetting because there are no jets haha. I think I'll forego the VOES for now and readdress it later if necessary. Thanks for the info!

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    VOES or Not

    It depends where you ride , when you ride, how hard you ride, how much you ride...

    Las Vegas in the summertime. Pulling the Baker Grade with some buds. 960 Feet ASL to 4130 Feet ASL in 19 miles. Pushing hard.

    (Baker Grade info - this ride will find the weak areas in your machine. If you can pull Baker Grade at 80 - 90 MPH in the summer in the afternoon your machine is set right.. http://wikimapia.org/24673889/Baker-Grade)

    This engine had about 2K miles on it.

    We built it, customer refused to invest in a VOES. Already had the Ultima ignition but he didn't understand the VOES and did not believe it was needed. He paid for the rebuild. If we would have installed a VOES and tuned the motor with the VOES we would have paid.....

    Timing control is essential when pushing hard in hot climates. Type of carburetor is not relevant. Correct carburetor tuning is..

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    Last edited by 69Glide; 05-05-2021 at 8:47 PM.

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    Ugh. Nice proof that systems which allow appropriate timing RANGE are a good idea.

    Also many HD owners lug the shit out of their bikes by upshifting too early and don't know what detonation sounds like or can't hear it due to loud pipes. Vibration makes the unaware want to upshift too early for that reason.

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    Quote Originally Posted by 69Glide View Post
    VOES or Not

    It depends where you ride , when you ride, how hard you ride, how much you ride...

    Las Vegas in the summertime. Pulling the Baker Grade with some buds. 960 Feet ASL to 4130 Feet ASL in 19 miles. Pushing hard.

    (Baker Grade info - this ride will find the weak areas in your machine. If you can pull Baker Grade at 80 - 90 MPH in the summer in the afternoon your machine is set right.. http://wikimapia.org/24673889/Baker-Grade)

    This engine had about 2K miles on it.

    We built it, customer refused to invest in a VOES. Already had the Ultima ignition but he didn't understand the VOES and did not believe it was needed. He paid for the rebuild. If we would have installed a VOES and tuned the motor with the VOES we would have paid.....

    Timing control is essential when pushing hard in hot climates. Type of carburetor is not relevant. Correct carburetor tuning is..

    Click image for larger version. 

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    Click image for larger version. 

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    Well I live in Phoenix. I'll be riding daily (hopefully) and I'll be installing an Ultima electronic ignition. I don't really know anything about timing control

  16. #16

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    Quote Originally Posted by confab View Post
    You can switch the VOES functionality off with the Ultima. Or at least on the shovel, anyway. Look for a dip switch on the front for VOES on/off.

    Does switching it off make the Ultima operate differently? Does it compensate for the VOES when you turn it off?

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    Quote Originally Posted by JudEl View Post
    Does switching it off make the Ultima operate differently? Does it compensate for the VOES when you turn it off?
    It turns off the VOES functionality.. The switch is dead when you turn it off.

    Basically, what a VOES does is ground under high engine load and sucks some of the timing advance out of the engine.

    Running hot. Running lean. Running with bad (Low octane) gas or running with too much ignition timing makes your engine predisposed to detonation. Detonation is "spark ping" or pre-ignition. This creates really high pressures in your cylinder and makes a hammering sound when it happens. (Can be hard to hear, cause Harleys are loud machines.)

    It acts like a hammer, too. Left unchecked for long periods of time, it will hammer a hole in the top of a forged piston or break the ring lands off of a cast one. It is very bad.

    BUT, your engine efficiency and performance are greatest when you are running as much timing as possible.. So, just backing it way down (retarded timing) causes problems too.. Like, too retarded and you do major damage also and build a ton of heat. I've actually seen headers glow BRIGHT orange because of this, and that will screw things up too. Quickly.

    So, the VOES is kind of a compromise.. When it senses a high load via the vacuum signal, it cuts some timing out to avoid pinging and damage.

    Generally speaking a lot of people jet a little bit rich and back the timing down to just under the threshold for pre-ignition and/or run a VOES switch to avoid all of these problems. Most of the switches are adjustable, even if they don't explicitly say so, so there's a little tunability to it.

    It is very important to run premium fuel for this reason.. Particularly in hot environments.. Because high octane fuel helps prevent ping. You should also do any tuning on it with the fuel you plan to run regularly. Don't fill it up with the good stuff, tune it, then drop back to low octane fuel. You're defeating the purpose of all that careful tuning if you do.
    Last edited by confab; 05-05-2021 at 11:24 PM.

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    PS: Higher compression engines take high octane fuel for this reason.. Higher compression makes more power, but you're closer to detonation with it.

    You really should be running premium fuel regardless, though..

  19. #19

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    Quote Originally Posted by confab View Post
    It turns off the VOES functionality.. The switch is dead when you turn it off.

    Basically, what a VOES does is ground under high engine load and sucks some of the timing advance out of the engine.

    Running hot. Running lean. Running with bad (Low octane) gas or running with too much ignition timing makes your engine predisposed to detonation. Detonation is "spark ping" or pre-ignition. This creates really high pressures in your cylinder and makes a hammering sound when it happens. (Can be hard to hear, cause Harleys are loud machines.)

    It acts like a hammer, too. Left unchecked for long periods of time, it will hammer a hole in the top of a forged piston or break the ring lands off of a cast one. It is very bad.

    BUT, your engine efficiency and performance are greatest when you are running as much timing as possible.. So, just backing it way down (retarded timing) causes problems too.. Like, too retarded and you do major damage also and build a ton of heat. I've actually seen headers glow BRIGHT orange because of this, and that will screw things up too. Quickly.

    So, the VOES is kind of a compromise.. When it senses a high load via the vacuum signal, it cuts some timing out to avoid pinging and damage.

    Generally speaking a lot of people jet a little bit rich and back the timing down to just under the threshold for pre-ignition and/or run a VOES switch to avoid all of these problems. Most of the switches are adjustable, even if they don't explicitly say so, so there's a little tunability to it.

    It is very important to run premium fuel for this reason.. Particularly in hot environments.. Because high octane fuel helps prevent ping. You should also do any tuning on it with the fuel you plan to run regularly. Don't fill it up with the good stuff, tune it, then drop back to low octane fuel. You're defeating the purpose of all that careful tuning if you do.
    Yeah I plan to run at least 91 octane (highest I've been able to find near me), if not 93 when I can find it. I'll have to do some research on tuning though. I'm unfamiliar with all that. Thanks for the all the info man!

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    Quote Originally Posted by 69Glide View Post
    VOES or Not

    It depends where you ride , when you ride, how hard you ride, how much you ride...

    Las Vegas in the summertime. Pulling the Baker Grade with some buds. 960 Feet ASL to 4130 Feet ASL in 19 miles. Pushing hard.

    (Baker Grade info - this ride will find the weak areas in your machine. If you can pull Baker Grade at 80 - 90 MPH in the summer in the afternoon your machine is set right.. http://wikimapia.org/24673889/Baker-Grade)

    This engine had about 2K miles on it.

    We built it, customer refused to invest in a VOES. Already had the Ultima ignition but he didn't understand the VOES and did not believe it was needed. He paid for the rebuild. If we would have installed a VOES and tuned the motor with the VOES we would have paid.....

    Timing control is essential when pushing hard in hot climates. Type of carburetor is not relevant. Correct carburetor tuning is..

    Click image for larger version. 

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ID:	110715

    Click image for larger version. 

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ID:	110716
    I'm assuming from the shape of the pistons that this was a shovelhead. But, no matter. As you raise the compression, the tuning becomes more difficult, or should I say, demanding, and the motor does generate more heat. This motor could have been tuned for safe operation without the VOES, but yes, the switch probably could have saved it. After all, hot rod shovelheads were built and run for years and years before the VOES equipped ignitions were developed.

    Jim

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