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Discussion Starter · #1 ·
morning ladies/gents. Got a 09 Vulcan 500 that runs but leaks fuel from Carbs. Took air filter out and was burnt to crisp, when I adjust idle knob to and turn off choke, she’ll die out. Too much air/fuel ratio? New to bikes and this is my first. Got her for $800 to learn. Rode her a few times and she wasn’t leaking then. Idk where to begin. Bought Seafoam, Marvel Mystery oil, using super premium gas as instructed, and had carb rebuilt and cleaned out when I first bought her. Sorry if I’m confusing anyone.
 

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You dont need premiun fuel.
Leaking fuel from carbs is a float problem in the carbs.
Most likely the rubber on the needle is messed up OR you have something stuck in there.
Either way you'll have to open them up.
 

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I agree with vulcandoc, you need to do a rebuild of the carbs. I don't know if the floats can be adjusted, or just have to be replaced for that bike. If they are not leaking, you may be able to adjust them. The float needle could be stuck or damaged or trash could be blocking its port. As he mentioned, you will probably need to replace the rubber parts on a bike that old.

Search the forum for a link to the service manual for your bike.
 
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And just to add, mine is a 1995, I bought it in 2012 and have not torn the carbs apart or had any fuel related problems.
So I dont think age has any play here, UNLESS the tank is rusting!
 

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morning ladies/gents. Got a 09 Vulcan 500 that runs but leaks fuel from Carbs. Took air filter out and was burnt to crisp, when I adjust idle knob to and turn off choke, she’ll die out. Too much air/fuel ratio? New to bikes and this is my first. Got her for $800 to learn. Rode her a few times and she wasn’t leaking then. Idk where to begin. Bought Seafoam, Marvel Mystery oil, using super premium gas as instructed, and had carb rebuilt and cleaned out when I first bought her. Sorry if I’m confusing anyone.
The idle speed knob doesn't have anything to do with the fuel enrichment circuit.
If fuel is leaking out and ending up in the air box..its the float valves...you may have junk getting on them from rust in the tank or from the fuel line deterioration on the inside of the line.
Pull carbs...look for junk in bottom of bowls..if there is debris present..chances are that is what has been causing your float valves to not seal properly.
You don't need high octane fuel...but if the machine is going to be sitting...alcohol free fuel is what you need...the gumming up process begins much faster with alcohol in the fuel as it attracts water ..also a more oxygenated fuel also leads to these problems sooner.
I have a 2009 ...although i didn't immediately run into float valve issues I did run into the pilot circuit clogging issue...white deposits..which are caused by alcohol in the fuel..when there is alcohol in the fuel it attracts water..once it's saturated..it separates.
Your location...temperature swings and humidity all play a part in how long the process takes..here in Missouri in doesn't take long at all

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Discussion Starter · #7 ·
The idle speed knob doesn't have anything to do with the fuel enrichment circuit.
If fuel is leaking out and ending up in the air box..its the float valves...you may have junk getting on them from rust in the tank or from the fuel line deterioration on the inside of the line.
Pull carbs...look for junk in bottom of bowls..if there is debris present..chances are that is what has been causing your float valves to not seal properly.
You don't need high octane fuel...but if the machine is going to be sitting...alcohol free fuel is what you need...the gumming up process begins much faster with alcohol in the fuel as it attracts water ..also a more oxygenated fuel also leads to these problems sooner.
I have a 2009 ...although i didn't immediately run into float valve issues I did run into the pilot circuit clogging issue...white deposits..which are caused by alcohol in the fuel..when there is alcohol in the fuel it attracts water..once it's saturated..it separates.
Your location...temperature swings and humidity all play a part in how long the process takes..here in Missouri in doesn't take long at all

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Thanks man, I’m at Fort Campbell on TN/KY border so temps do swing. Also I tried spraying Carb cleaner while running it to see if it’ll help ungunk it. I also added Seafoam to gas to help clean carbs before taking it out. I was able to see what was going on since air filter is off. Got flames inside air box and carbs. Definitely feel like I need a new Carb. Any thoughts???
 

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No on new carbs - just clean what you have! And install new parts.
There is a parts kit for after you clean them. Dont know part number or from where.
 

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Thanks man, I’m at Fort Campbell on TN/KY border so temps do swing. Also I tried spraying Carb cleaner while running it to see if it’ll help ungunk it. I also added Seafoam to gas to help clean carbs before taking it out. I was able to see what was going on since air filter is off. Got flames inside air box and carbs. Definitely feel like I need a new Carb. Any thoughts???
Spraying carb cleaner while running won't clean the internals.
You are going to have to pull the carbs and clean em..the pilot jet and transition ports clog on these..causing low speed problems..such as popping through the carb...difficulty in setting idle speed...and the engine taking a long time to slow down after the throttle is released
The float valve hanging is usually caused by debris from inside the fuel line itslef or a nasty tank...it is possible to have corrosion in the float needle and its seat causing it to fail to shut properly as well..those are usually the nastiest carbs though.



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Spaying carb cleaner into the carbs is a great way to dry out and crack the little "O" rings on that butterfly shaft. Yep, just on the other side of the carb all along that shaft is a "O" ring on either side. Once they dry out and crack, you have a hell of a time getting the bike to idle well. Air leaks from that shaft.

Live and learn...Here is the thing with all carb bikes. You really need to take the time to remove them and clean them well. Most carbs have issues when they sit for 6 months or longer. With our new 10 to 15% eth add, the gas separates and starts to do damage faster then straight gas.

Watch a few vids on youtube and get to work on those carbs. If gas is dripping from the carbs can only be a few things.

1. Float height is wrong and it is just coming up through the opening going down into the fuel bowl.

2. Float height is correct but the jet that stops fuel from entering the bowl is not doing its job.

3. Are the bowls leaking at the sealing location to the carbs? New gaskets.

Bottom line take a look at them or having someone take a look at it. I think I read that the air filter was burned. The third issue would not cause that...so maybe 1 or 2 or both are happening.

Once you put the time into the carb and the bike runs well, you will understand why it is the one thing that really needs attention. Good luck
 

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Discussion Starter · #12 ·
Spaying carb cleaner into the carbs is a great way to dry out and crack the little "O" rings on that butterfly shaft. Yep, just on the other side of the carb all along that shaft is a "O" ring on either side. Once they dry out and crack, you have a hell of a time getting the bike to idle well. Air leaks from that shaft.

Live and learn...Here is the thing with all carb bikes. You really need to take the time to remove them and clean them well. Most carbs have issues when they sit for 6 months or longer. With our new 10 to 15% eth add, the gas separates and starts to do damage faster then straight gas.

Watch a few vids on youtube and get to work on those carbs. If gas is dripping from the carbs can only be a few things.

1. Float height is wrong and it is just coming up through the opening going down into the fuel bowl.

2. Float height is correct but the jet that stops fuel from entering the bowl is not doing its job.

3. Are the bowls leaking at the sealing location to the carbs? New gaskets.

Bottom line take a look at them or having someone take a look at it. I think I read that the air filter was burned. The third issue would not cause that...so maybe 1 or 2 or both are happening.

Once you put the time into the carb and the bike runs well, you will understand why it is the one thing that really needs attention. Good luck
Thanks man. Took it apart and cleaned it. Hoping it want the fuel valve needles
 

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So you just cleaned the fuel valve needle? You have to look at the needle closley to see if it has a "ring" on the nose as it goes into the holder. That is if it is the rubber type. If the nose of the fuel valve is damaged it will leak.

Another thing you might have to do is a "wet set" of the float in the bowl.
Take a look at that vid and it will really help to clear things up. Keep us updated....
 

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Thanks man. Took it apart and cleaned it. Hoping it want the fuel valve needles
Hope you haven't put em back on yet.
Need to use a q tip to clean the float valve seat.
Need to back blow the pilot circuit..Need to remove pilot..clean all little holes..poke the the transition ports with wire..back blow again...the main doesn't clog often but while you are there..just as well clean...you can usually leave the top together as the diaphragms in these usually hold up to age.


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Hi Doc,
  • FIRST and foremost, you should have the factory service manual in some form. It is imperative to have the best information possible at your disposal!
  • Second, you mentioned flames coming from the airbox and carbs. An overfilled carb bowl will leave raw fuel pools in the carb that wont burn. Did these flames seem to shoot out or did they just tend to go up as soon as they found their way out of the carb bore?
  • The reason I ask is that several things can cause either situation but both are very different in their causes. The shooting flames are generally quick and controlled by ignition (albeit incorrect timing) within the cylinder. The other is a little more sinister, unpredictable and can literally burn your motorcycle to the ground.
  • Before we get into all that, bench test the carbs for FUEL level with an auxiliary fuel source BEFORE installing the carbs back into the rubber isolators.
  • This is also a great time to inspect the rubber isolators for cracking which can cause lean mixtures and EXTERNAL FIRES.
  • Another important component to think about replacing which is often overlooked during a carb 'rebuild' are the fuel pipe O-rings. If damaged or even disturbed from their years long comfort zone they can leak fuel and cause EXTERNAL FIRES.
  • Another often overlooked function within the carb are the FLOAT NEEDLE SPRING PINS. At the opposite end of the rubber sealing cone is a little pin sticking out. It should push in and return quickly upon releasing it. If it doesn't, you can try to clean and lube to get it to function. I would replace them. You should have new FLOAT NEEDLES since the carb was recently rebuilt.
  • Being rebuilt: That brings me to another point of discussion. There is a massive difference between rebuild, refresh and cleaning of carbs. Most people "refresh" carbs when they talk of "rebuilding" carbs.
  • If you "rebuild" a carb there is no component that isn't new other than the carb body, the float bowl and probably the slide cap. Rebuilding a carb is expensive and sometimes replacing the carb is cheaper.
  • 'Refreshing' a carb entails replacing parts that wear with time or operation and cleaning other parts that can be cleaned if necessary. Things like O-rings, seals and other rubber components. Jet needles that wear out from rubbing against the emulsion tubes. Usually in a multi bank of carbs they won't be separated whereas in a rebuild every carb will be separated from the other.
  • Cleaning is just that. A can of carb cleaner will clean jets, emulsion tubes, gunk from bottom of the float bowl and dazzle up the outside. A good set of wire gauge spring steel cleaning wires is handy to push out gunk from jets and emulsion holes. You will find these holes on the main jet emulsion tube and the pilot jet.
  • And now back to the flames: Shooting flames are known as "back fire". A condition caused by late ignition either from a wasted spark ignition system, low compression with incomplete slow burn or hot carbon spots on the piston face or compression chamber. All of these are correctable conditions with a little testing a diagnostic work.
  • The slow burn flame: A hot cylinder, an open intake valve and a bad fuel tank vent and/or leaking vacuum petcock diaphragm...Your bike can and others have burned to the ground under these conditions. And if you park your bike in the same garage as your 1965 mustang guess what else might go up in flames. That's right, your wife's SUV.
 

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Discussion Starter · #16 ·
Cleaned whole carb which is why she’s working great. One problem now; my idle knob chord detached themselves from each other. Any help?
 

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Hi Doc,
you will probably have to replace the idle adjustment screw cable
Do you have a local motorcycle salvage? I would check there or you can just order one. Those components are almost universal in application.
 

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Discussion Starter · #18 ·
Hi Doc,
you will probably have to replace the idle adjustment screw cable
Do you have a local motorcycle salvage? I would check there or you can just order one. Those components are almost universal in application.
Thanks, where could I order it from?
 
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