Carb Vent Hose? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 11 (permalink) Old 04-05-2007, 08:29 PM Thread Starter
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Carb Vent Hose?

Howdy all,

I am trying to figure out the issue I am having with my bike surging at speeds. A common fix people have recommended is to check the carb vent hose to ensure that it is not plugged. Unfortunately I can't find the hose! Can anyone gimme a pic of what I should be looking for?

Thanks all

Update:

I started trying to tune the fuel mix screws, and it seems that I have managed to ruin something. The bike has no power, and is now surging really bad in all gears. The plugs are new, good battery, the bike is mechanically stock. Any ideas?

Last edited by rbarrett49; 04-05-2007 at 10:04 PM.
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post #2 of 11 (permalink) Old 04-05-2007, 08:44 PM
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Check the photos I posted in the Gallery (Carb Parts 101 Properly Labeled) as a starter; but here's a pic from my bike before I started working on it - the vent hose is the small hose on the right side - that in this case doesn't appear to be connected to anything at all (hmmm).

C

Last edited by Crobins365; 08-29-2007 at 09:31 AM.
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post #3 of 11 (permalink) Old 04-05-2007, 10:08 PM Thread Starter
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Hose...

Where does the other end of the hose attach?
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post #4 of 11 (permalink) Old 04-05-2007, 10:26 PM
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Quote:
Originally Posted by rbarrett49 View Post
Where does the other end of the hose attach?
one end connects to the carbs, as a reference to the outside pressure... the other end doesnt connect to anything.. normally its attached at the back of the right ear... but there is just a lil holder there... nothing else... what i did to mine was cut it at a 45 deg angle... that keeps it from getting blocked... also check for pinching..

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post #5 of 11 (permalink) Old 04-05-2007, 10:29 PM Thread Starter
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I have had my tank off and poked around in there and couldn't find a hose coming from the carbs and leading to nowhere. Can you be a little more specific?
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post #6 of 11 (permalink) Old 04-06-2007, 12:31 AM
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Going by the illustration in the Clymer manual there should be two hoses(one from each carb) coming into a T then one hose from the T to the back inside of the right hand air filter housing


Quoting from the manual

" Do not insert the hose too deep into the receptacle in the housing"

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post #7 of 11 (permalink) Old 04-06-2007, 07:37 AM
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https://www.vn750.com/photopost/showgallery.php?cat=548

Check the last photo - it's kinda hard to see, but there is a vent hose that comes off of each carb, and they connect together onto a (in this case) black t-fitting. On these carbs, I have a blue vent hose coming off the t-fitting and venting out (eventually) to the airbox.

Your carbs should have the following:
Two fuel lines
Two vacuum hoses or at least ports (if the hoses are off, the ports are brass nipples)
Two vent hoses (very small) that connect to a t-fitting between the carbs (can't really see it with the carbs on the bike); then one vent hose comes off of the fitting and vents out.

Tell us a little what you did when you "adjusted the air-fuel mix screw" - step-by-step, and maybe we can all walk you back to the starting point.

C
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post #8 of 11 (permalink) Old 04-06-2007, 11:15 AM
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It is entirely possible that you are having issues that aren't really related to what you did. First off, the fuel mix screws don't have much of an effect on anything but idle. Once you roll on the throttle, you are in the the jets mixture and not the idle mix. It sounds like you probably have some crud in your carbs that is messing with your higher rpm running. My first thought would be to take the idle screws in all the way til they bottom out (lightly--do not put any pressure on them bottoming out!) and then back them out about 2 full turns. Then leave them alone for now. Then I'd add about 1/2 can of seafoam to a full tank of gas, start the bike and let it idle a minute or so then shut it off and let it sit a day or so. See if that helps clean things up some. Then report back.

It could also be related to other things, like the vent hose, vacuum leaks etc. but until you have tried seafoam, I wouldn't fiddle with anything else. Let's take it a step at a time.

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post #9 of 11 (permalink) Old 04-06-2007, 06:21 PM Thread Starter
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I turned the screws in all the way and then turned them out 2 turns. Before that I had the tank off and was trying to trace the vacuum lines/fuel lines/all of the other plethora of hoses running everywhere. The bike starts and idles great, and when I ride it it even runs like it should--lots of power. Then after about 30 seconds it starts cutting out really bad. Before I started playing around it would only cut out at higher speeds (cruising) but now when it starts dogging it is in every gear.

I am thinking that maybe when I pulled off the tank and started tracing all the hoses that maybe I created a vacuum leak somewhere. I will go back and ensure that everything is still connected. I will also load it up with Seafoam.

I appreciate all of the help, keep the good ideas coming!
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post #10 of 11 (permalink) Old 04-06-2007, 10:13 PM
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There is a vacuum hose on the fuel petcock that runs to the left card. This hose causes the diaphram in the petcock to open and allow fuel to flow to the carbs. If it is not contected you will have the problems that you stated last. Look on the left side of your bike. Find the petcock. There should be three hoses coming from it. The two from the sides lead to the carbs. The one on the bottm should have a hose going eo the front carb. I hope this salves your problem. I know it did some of mine.

The other hose that you are looking for allows the carb bowls to breath is located in the middle of the two carbs and run to the right ear


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