Carb vacuum/voes?
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Tourer
Joined: Jun 2012
Posts: 365
Likes: 18
From: Cheyenne, WY
Carb vacuum/voes?
Hey everyone,
On a good note for today, i re-wired my ignition and lights and now everything works.
Ok, so the previous owner had a weber carb on the evo that was just a fuel line and throttle/idle cables ( no vacuum lines)
well i bought a cv carb to install on the back but i dont know what to do with the voes on it. my intake manifold does not have a hole to were the voes would go ( from how i understand it thats where the line would go, correct me if im wrong )
my question is can i just plug the outlet or do i need to create something that will work?
i know the system is for a vacuum advance for the motor, but if it was running without it from the last carb, do i need to install it theis time? and how would i go about doing it?
On a good note for today, i re-wired my ignition and lights and now everything works.
Ok, so the previous owner had a weber carb on the evo that was just a fuel line and throttle/idle cables ( no vacuum lines)
well i bought a cv carb to install on the back but i dont know what to do with the voes on it. my intake manifold does not have a hole to were the voes would go ( from how i understand it thats where the line would go, correct me if im wrong )
my question is can i just plug the outlet or do i need to create something that will work?
i know the system is for a vacuum advance for the motor, but if it was running without it from the last carb, do i need to install it theis time? and how would i go about doing it?
Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
Would have a nipple for plugging hose from carb to voes. If you don't hook up a voes you timing will always be Advanced, some like it that way and
Plug the carb and ground the voes.
Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
I might add it is not recommended going without the voes as it does help prevent detonation. I may also have that backwards with voes grounded making ignition advanced all the time, buti think it's correct.
Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
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Tourer
Joined: Jun 2012
Posts: 365
Likes: 18
From: Cheyenne, WY
any idea where that switch is located?
because i think i might have seen something like it, wont know until tomorrow, as it just now got dark outside
because i think i might have seen something like it, wont know until tomorrow, as it just now got dark outside
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Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
If its mounted in normal location it'll be directly behind and in line with the top of the carb, between the heads, behind enrichener ****, right next ti fuel line coming from petcock. Take your pick.
Road Warrior
Joined: Jun 2009
Posts: 1,687
Likes: 9
From: SoCal & West TN
The VOES (Vacuum Operated Ignition Switch) is used on the Harley V2 Ignition. To expand a little on VOES. The Solid State Ignition (V2) Harley first used has two MAP ignition charts in the memory. The VOES will tell the ECM to select the correct one according to the load on the motor. This is based on the vacuum in the intake. The ECM is the solid state replacement for the "Breaker" and counter weight used on the original ignition.
The Harley ECM will still operate without the VOES in place. Without the VOES in place the ECM will not adjust to the correct operating curve. It can result in poorer fuel economy and some pre-ignition. The motor can "kick back" and cause damage to the starter and the bendix gear, but may not. You could hear some "Pinging" or not. This depends on how you ride and the grade of fuel used. It is like using the older "Counter Weight" advance system with the weights rusted and not moving according to the speed of the motor. Some aftermarket modules use the Harley VOES to control their ignition module. But most do not use the switch but adjust based on the RPM only.
If the ignition now used on your bike doesn't use the switch, you will not need it with the CV. The VOES has nothing to do with how the carburetor operates. So you can cap any vents used for the VOES and remove it if one is mounted on the CV you are going to use.
The Harley ECM will still operate without the VOES in place. Without the VOES in place the ECM will not adjust to the correct operating curve. It can result in poorer fuel economy and some pre-ignition. The motor can "kick back" and cause damage to the starter and the bendix gear, but may not. You could hear some "Pinging" or not. This depends on how you ride and the grade of fuel used. It is like using the older "Counter Weight" advance system with the weights rusted and not moving according to the speed of the motor. Some aftermarket modules use the Harley VOES to control their ignition module. But most do not use the switch but adjust based on the RPM only.
If the ignition now used on your bike doesn't use the switch, you will not need it with the CV. The VOES has nothing to do with how the carburetor operates. So you can cap any vents used for the VOES and remove it if one is mounted on the CV you are going to use.
Last edited by Ultra89Rider; Jun 16, 2012 at 01:51 AM.