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Discussion Starter #1
Hi folks,

I'm new to the forum and am actually trying to help a buddy with his VN750. When looking at the petcock straight on - which fuel line leads to the "front" carb?

I'm assuming that the vacuum line and right (rearward) line go to the front carb and the left line goes across to the rear carb.

We suspect a the left/front carb is sticky. I drained the front carb last night and tried to introduce some sea-foam via the fuel line but am second guessing myself. FYI, I used a syringe and a length of tubing (3/16ths maybe?)that slid inside the fuel line to deliver the seafoam with very little spillage.

Thanks in advance
 

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Does it really matter which is which? Think I've had them both ways.
 

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Sparky!!!
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well, if its a petcock with "Prime, then there won't be a vacuum line... and as long as the "reserve" style petcock is getting vacuum to the vacuum port, then it doesn't matter which line goes where.
 

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Discussion Starter #5
Thanks for the reply;

The carb drain and flush has seemed to do the trick. After blowing out the residue the bike was idling and running very nicely.
 

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Check the tank for rust.
 

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Use seafoam often. About every 3rd fill up is about what I do. Keeps everything squeaky clean and haven't had a problem yet.
 

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Linkmeister Supreme
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well, if its a petcock with "Prime, then there won't be a vacuum line... and as long as the "reserve" style petcock is getting vacuum to the vacuum port, then it doesn't matter which line goes where.
slim are you sure about this?

This is the first time that I have heard that early "PRIME" petcocks don`t have a vacuum line. I haven`t researched it, but I had assumed there was a gravity feed provision for the PRIME position only, and the RUN and RESERVE positions were vacuum operated as are the later models.
 

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Discussion Starter #9
Use seafoam often. About every 3rd fill up is about what I do. Keeps everything squeaky clean and haven't had a problem yet.
Roger that, I'm a believer in the Seafoam. I add a couple ounces to my tank every month ('04 Ducati 999S).

My buddy's Vulcan went through about a can and a half together with the treatment I mentioned above. After a few impressive smoke shows its running better than ever -

The reason I asked about the lines is that I only injected the Seafoam into one line, believing it fed the front carb which we identified as the cuplrit. I just wasn't sure but it doesn't matter now.

I am sure his tank is full of rust, the gas from the carbs looked like orange gatorade with a couple of varnish slicks floating in it. I just got him a newer petcock (found one cheaper than the rebuild kit) and will treat the tank soon. Last time I did a tank I used some stuff (acid, neutralizer and coat) from a Harley shop, I can't remember what it was called but man it went on nice.
 

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Sparky!!!
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slim are you sure about this?

This is the first time that I have heard that early "PRIME" petcocks don`t have a vacuum line. I haven`t researched it, but I had assumed there was a gravity feed provision for the PRIME position only, and the RUN and RESERVE positions were vacuum operated as are the later models.
Not 100% sure, but on my CX it has run-off-prime... no vacuum port, so I was assuming that most petcocks that are listed as prime are gravity fed only. My assumption could be wrong though
 

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Roger that, I'm a believer in the Seafoam. I add a couple ounces to my tank every month ('04 Ducati 999S).

My buddy's Vulcan went through about a can and a half together with the treatment I mentioned above. After a few impressive smoke shows its running better than ever -

The reason I asked about the lines is that I only injected the Seafoam into one line, believing it fed the front carb which we identified as the cuplrit. I just wasn't sure but it doesn't matter now.

I am sure his tank is full of rust, the gas from the carbs looked like orange gatorade with a couple of varnish slicks floating in it. I just got him a newer petcock (found one cheaper than the rebuild kit) and will treat the tank soon. Last time I did a tank I used some stuff (acid, neutralizer and coat) from a Harley shop, I can't remember what it was called but man it went on nice.
You might want to think twice about using the tank coating. Some on here have used that and over time it turns to sludge and is worse then rust in the tank. I would suggest to clean the tank to get the rust out and always keep it full. Condensation from leaving the tank less then full is the reason for tanks rusting. I have a 93' and an 01' that have always been kept full and you can look in there and they look brand new.
 

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Sparky!!!
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baldy... it depends on the coating... KREEM sucks... I use(d) POR-15 with out any problems on lots of cars and motorcycles... I have 20 years on my CJ3b gas tank with POR-15, also this jeep sits about 5 years at a time with gas left in the tank, and no maintenance between runs other than a battery charge and a fuel stablaizer. ... just fallow the instructions, and make sure you rpep the tanks propperly.
 

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I have a "Prime" petcock (on an 85 VN700) and the positions are res-on-prime.

There IS a vacuum line going to it.
 

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If the tank is cleaned and you keep the tank full to minimize condensation, why line it?
 
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