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On my bike I am putting together I am ready to put the motor, trans, primary, and carb on the bike with a few other various bits. So, I have some general questions. Bike is on 1999 FXST frame, motor is from 1996 Road King (was EFI and will now be carb), transmission is a normal OEM 5 speed, carb is a completely rebuilt HD CV, air cleaner setup is a HD screaming eagle for a late 90's softail, Thunder Heart wiring harness, and primary inner and outer are stock HD with a BDL enclosed belt drive. I have a service manual and parts manual for the bike. For the life of me I cannot find this info in there.
1. What size and type fuel line does this bike take? Did some reading and the Pingel petcock I am gettign has a 5/16" barb, so that one is answered.
2. What size and type oil line? (I believe it is 3/8" ID)
3. What size and type vacuum line between VOES and carb?
4. Bolt size to mount the VOES to the back of the top motor mount?
5. I am installing a non-vacuum Pingle petcock, so the only vacuum line I should have to worry about is between the VOES and carb. Is that correct?
Lastly, I have read tons of stuff about VOES. On my last bike I built, I did not use one. However, that bike had a 113" Ultima motor, S&S Super G, and an Ultima ignition. The instructions for the ignition said not use one so I didn't. This bike the motor is a stock HD 80" EVO, the carb is a stock set-up CV with a 175/45 jet set-up and I will be installing a Dyna 2000i ignition on it. I am doing that for a couple reasons. The motor was EFI and will now be carb, and I may do performance upgrades at a later time so I want a programmable ignition. I will also be running the bike as single fire operation. So, all that being said, is the VOES necessary? I don't mind sticking one on there, but I try to keep stuff as simple as possible.
Fuel line - 3/8 or 5/16, see what fits best. The hose with green lettering is ethanol resistant.
Oil line - I use 3/8 automatic transmission hose, it's made for hot oil, but is a little thicker.
For both, I use fuel injectionclamps, they are easier on the hose than the usual screw type.
VOES uses standard vacuum hose, 1/4" I think, and yes, there are no other vacuum hoses. I found VOES helpful to allow use of the faster advance curves on the module without pinging at low RPM higher loads. IE to avoid a downshift. If you look at the curves in the instructions, there's ones with the VOES wire grounded, and much slower ones without. VOES picks the right one for the situation.
No, I will be installing a Dyna 2000i ignition on it. is the VOES necessary ? I don't mind sticking one on there, but I try to keep stuff as simple as possible.
I bought a VOES and will install it. Also figured out it doesn't need hardware to mount it since it fits in a hole on the enricher bracket and is held in by a provided retainer ring. Bought some fuel line and vacuum line at lunch. So far the auto parts places I have been to were out of 3/8" oil line so still need that.
Ultima recommends not using VOES because the motors are higher performance and don't like to run the advanced curve at the vacuums the typical VOES switch points. On a stock motor, the Voes will get you some extra mileage.
Ultima recommends not using VOES because the motors are higher performance and don't like to run the advanced curve at the vacuums the typical VOES switch points. On a stock motor, the Voes will get you some extra mileage.
Thanks for that. I bought a VOES and will install it. I can always remove it later of needed.
Your VOES should be 3/16" vacuum line to the carb port. The inlet barb on your CV40 carburetor is 1/4", and my stock petcock out barb is also 1/4". I replaced the hose last week so I'm sure of that.
If the Pingel barb is 5/16" you have a mismatch. Whether that is of concern, IDK. I like my gas connections to match if possible. I looked at the Pingel website and don't see a 1/4" outlet offered. Seems odd to me, but maybe aftermarket carbs have bigger fuel inlets and that's their main market, not us guys with 30+ year old stock carbs.
I'm using a 2000i with VOES on my 1250 Sportster motor, set on the mildest curve, 1 or 4 but I forget which.
John
Last edited by John Harper; Mar 3, 2026 at 05:54 PM.
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Fuel and Oil Questions
