She's gasping for fuel

[Mike M in ohio]

     Quick question for the tech gurus who are always so helpful:
     I have an '03 standard that has been flawlessly performing for the two years I've owned her. But, in the past week, a small issue has arisen. About a week ago, I fired her up (no choke, it was warm) and proceeded down the road. As I did, within a half mile or so, she began to lag, as if not getting enough gas. (it felt like I had left the petcock on off.) I pulled to the shoulder, checked the petcock, (it was on) and peeked in the tank. (about half full) I then restarted, and she ran perfectly. I did about sixty miles with no more issues.
     Today, a colder day requiring choke, when I started her up....she fired with the choke but again sounded strained as if not enough gas. (I know I had topped her to full when last she was put away) And after a minute, when I tried to lessen the choke, she just kept dying. I repeated a similar routine as last time, rechecking the petcock, and glancing into the tank just to be sure.
      And, just as before, she fired right up and ran like a champ, covering some 90 miles with lots of stops and starts. So, please tell me, is there some type of vent that might be blocked intermittently or, any other fuel feed issue that I should check? I appreciate any and all guidance. Mike in N.Y.

[gordonv]

It sounds more like a vacuum leak to the peacock, not staying open.

Have you had your tank off or added a fuel filter to the fuel line?

[Steel cowboy]

try running with the gas cap loose if it happens again the vent could be clogged or it could be a vacuum leak. If you suspect a vacuum leak, it could be the o rings at the base of the manifold were they meet the head. The clamps that secure the carb to the manifold's too. Look at the vacuum line, one goes to the petcock ( #6 carb left rear ) the #4&3 go to the pair valve and 1,2&5 have rubber plugs. I sprayed some WD40 around the vacuum lines to find my bad ones before I did the desmog procedure.
Hope you find it, great riding weather is coming to the north east.

[Chrisj CMA]

Classic signs of early petcock failure.  Same happened to me and kept getting worse until I got rid of the OEM and replaced it with a Pingel

[hubcapsc]

Classic signs of early petcock failure.

I agree... to fix the one you have search "cover set" and you'll find the
fix and Honda part numbers... if you do it, it will be easy to change the fuel
filter at that time.

I remember the cover set as being $25 or so and the filter $10 or so...

-Mike

[Ricky-D]

I think any time that a carburetor/fuel problem is considered the first thing to do is drain a little gas from each float bowl to insure any crap/crud is hopefully removed, AND then add a large size dose of a fuel additive to a tank of fresh gasoline. (I like Techron). Most times this will make a difference, noticeable after a hundred miles or so.

***

[MarkT]

The Valk is notoriously touchy about fuel feeding.  Might be hard to define the exact cause while still fixing it.  The OEM petcock has many problems.  If I was you, I would order in a Pingel to eliminate a raft of problems from the Honda petcock. (I did do this - I was having feed problems.) I also added a lever extension to the Pingel lever to make it easier to reach.  I suspect your problems are with the petcock.

Secondly, make sure you have downhill angles only on the line from the tank to the T at the carb rails.  Any upward angle will allow an air bubble to form which makes feeding intermittant. Depends on flow demand, head pressure in the tank, ambient temperature along with the heat accumulated between the carbs.  

Ensure you don't have a venting issue.  You can test this by putting a penny under the gas cap seal.

On Jade, I replaced the smaller Dan-Marc with the bigger one.  I was getting starvation while hauling a heavy trailer cross country in high temps at highway speeds. Mileage was as low as 18mpg so you can see I had high fuel demand. If you have high demand, consider this.

If you have any mods on the fuel line like adding a filter, remove it.  Straighten any loops, remove excess line - keep it short.

Lastly, give your bike a Berrryman's B12 treatment.

I no longer have any fuel problems - while Jade's fuel system is heavily modified - as described here before.