Project bike is going well! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

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post #1 of 47 (permalink) Old 01-15-2018, 05:55 PM Thread Starter
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Project bike is going well!

Well, sort of. I got a 1997 VN750A from a friend of mine for free. It turns and has been run off of some starter fluid once or twice but needs serious TLC. So anyway, today I hooked up the carbs. I had to put on a single-port petcock from ebay, sadly, so I had to tee the fuel lines and then have a long-ass hose for a fuel filter. I got all that hooked up, and the vacuum hoses (though I need replacements, I need some help with that) are connected. I however could not find the hoses for the two middle nipples on top of the carb. The one that has an OEM Tee, my buddy never gave me those hoses. So anyway, all that's hooked up and I try to fire it up... Nada. The gas is flowing, but only one side of the carb so far has any fuel in the bowl drain. The other side is dry as a bone. Not only that, but apparently my battery lost its charge over time in the cold from the garage, so it won't fire that way at all. What am I missing, or what should I look for and do the next time I go over to start fixing it up?
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post #2 of 47 (permalink) Old 01-15-2018, 06:57 PM
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Could be a stuck float/needle? A bit of judicious tapping on the side of the bowl might be enough to loosen it up.
Have you checked for fuel in the line going into the dry carb to eliminate a crimped hose, clogged T branch etc?

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post #3 of 47 (permalink) Old 01-15-2018, 09:59 PM Thread Starter
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I checked and none of them were crimped. It's possible it's a stuck needle and I'll give it a tap to see. This is the first time in a while it's had gas flowing through a tube at all so is it possible that gas hasn't gotten into the float yet? The hose I used is a bit longer than stock, by like 5 inches. Having to tee the hoses also may not have been proper. Not sure.
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post #4 of 47 (permalink) Old 01-16-2018, 02:46 AM
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I've heard different opinions about a T after the petcock, but unless you're REALLY pushing the fuel through the engine at high RPM it shouldn't be a problem.

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post #5 of 47 (permalink) Old 01-16-2018, 02:28 PM
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can you blow through the hose on the carb not getting fuel?

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post #6 of 47 (permalink) Old 01-16-2018, 07:49 PM Thread Starter
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Hey all! I just got back from visiting the bike to work on it. I got it fired up and it will run, but only with throttle. I also have no choke cable so it's even harder to work with honestly. Anyway, both cylinders ran fine, which leaves me wondering how gas is getting to the dry one. Another issue that's cropped up is that over time fuel just won't deliver through the hose and in-line fuel filter, it just goes dry. I'm using the setup I attached for it, let me know how awful my job was. I believe one of the vacuum hoses is blocked up a bit but I'm unsure. I've also yet to blow into the hose for the dry carb, so I'm not sure about that one either. I need advice on how to get her to idle, mainly. I can set the bike's fuel back up, but I don't want to get excited and then have to take it all off again.

So! Main question: How can i get her to idle AND run on throttle properly? Is my hookup to blame? My carbs? Or something I'm missing?

Fuel lines in question: https://imgur.com/gallery/CBqkJgc
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post #7 of 47 (permalink) Old 01-16-2018, 08:40 PM
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your fuel line is to long/ run poorly. the carbs are gravity fed not vacuum. so shorten the line after the filter and run it more horizontal. the less the fuel has to climb the better.
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post #8 of 47 (permalink) Old 01-16-2018, 08:42 PM
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Shorten the hoses so they all run downhill, it's trying to gravity feed through that hose that is looped down, then upward.

The filter isn't helping fuel flow. Some have been able to use a filter, others have to remove them to get flow.

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post #9 of 47 (permalink) Old 01-16-2018, 08:56 PM
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Also, check that filter to see if there's an arrow for flow direction. Looks like it's backward, it's filtering from the inside out. edit: Maybe it is the right direction ... If the hose looping down the front cylinder is coming from the petcock.

edit: The hose sizes don't look right to me, but it might be the picture. The line on the filter looks like the larger automotive size, (maybe 3/8"?) and back toward the carbs it looks like smaller windshield washer hose size (1/4"?).

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Last edited by Spockster; 01-16-2018 at 10:15 PM.
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post #10 of 47 (permalink) Old 01-16-2018, 10:14 PM Thread Starter
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Nope, the hoses running from petcock to filter to carb tee is 1/4", then the two branches into the carb nipples are 5/16" OEM hoses. I'll take into account the hose length. I thought it was vacuum fed though? Otherwise what's the point of vacuum hoses and, you know, the petcock not having an off option.
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