What's the difference?

[Doc809]

You guys know I am mechanically challenged and am completely willing to show my ignorance, so here goes.  We are trying to figure out why Joe's 03 suddenly started getting 15 miles to the gallon.  In checking the vacuum nipples on the back of the intakes I notice mine (99 std) are getting rubber rot and replace them.  In checking his I find that he has vacuum lines attached to two of them on the right and one of them on the left.  NIpples on the other three. Mine has none. What the difference?  I would take it in to have it evaluated but I just spent $300 on mine correcting the problem created by the stealership when they wired my running lights through my headlight.  Burned out the switch, melted wires at the fuse box and a few other screw ups.  Any suggestions would be appreciated. L

[laserpat]

1 line activates the fuel valve in the petcock. Yours might not have oem petcock. also some California models have extra plumbing

[Houdini]

Does Joe have a vacuum operated cruise control installed?

[Doc809]

No cruise control and I thought about the CA model. But this one was sold by Honda/Suzuki North new to Nate Newton of the Cowboys.  Bike got repossessed and we bought it with 2K miles on it.  Just wondering why three cylinders have lines and three don't when mine doesn't have any.  Really perplexed with the 15 mpg.

[Daniel Meyer]

No cruise control and I thought about the CA model. But this one was sold by Honda/Suzuki North new to Nate Newton of the Cowboys.  Bike got repossessed and we bought it with 2K miles on it.  Just wondering why three cylinders have lines and three don't when mine doesn't have any.  Really perplexed with the 15 mpg.

1 line for the vac operated petcock.
2 lines for the pair valve (emmissions stuff).

On the mileage, I recommend checking the petcock function. Often the diaphram becomes bad/leaks vacuum and this will result in a vacuum leak and bad fuel flow (which will actually reduce your mileage).

Pull the tank.

With the petcock "off" use a mity vac/etc to put a vacuum on the vacuum nipple of the petcock. It should not leak down. If it does the diaphram is bad, rebuild the petcock.

Release vacuum. Turn petcock to on and then reserve. NO fuel should flow.

With petcock in "on" apply vacuum. Fuel should flow. Release vacuum, fuel should stop (may take a few seconds). Do the same for reserve.

Any deviation from above and the petcock needs rebuilt or replaced.

Also check the vacuum line to the petcock and the other lines as well.

[godfire]

Doc,
We can walk through the steps that Daniel outlined at the next wrench party.
It is pretty easy stuff.

Also Joe's bike is stock (with the three vacuum lines) sounds like your bike has been desmoged at some point. http://www.valkyrieriders.com/shoptalk/desmog.htm

I was getting around 20mpg before I replaced all my vacuum lines and plugs.
If the vacuum lines have not been replaced, I would recommend replacing them when we check the petcock.

I like these (no affiliation)
http://sites.google.com/site/valkparts/

You would need:

1. Valkyrie OEM Petcock Vacuum Line
2. Valkyrie Pair Valve Vacuum Line
3. Valkyrie Vacuum Cap Kit

[Doc809]

Thanks guys.  Always appreciate your input.  Lookin forward to fixin this thing. L

[Hollywood]

I talked to redneck about your problem. Unless you're leaking a lot of fuel, the petcock valve or lines is probably NOT your problem. You're running rich, which is why you're not getting good mileage. When is the last time you changed or serviced your AIR filter? Changed oil and filter? plugs? Most likely if you have recently done a tuneup. your needle valves in your carburetor are clogged or worn out Your carbs may need to be synced . The gas nowadays has a great impact on wear and tear on your engine. He suggested you do this 1st, before going thru the time and effort and expense of changing out your petcock lines, which may not resolve the problem. the fuel valve really has nothing to do with gas mileage.  If you want to talk to him further so he can explain, call friday. 682-465-5739

[Doc809]

Thanks for the suggestions.  Oil/filter have about 2K miles on them.  New air filter, plugs changed 1500 miles ago.  New Cobra jet needles placed in the carbs when we changed to Cobras, 5K ago, carbs were syncd at that time by Al Lambs.  No fuel leaks anywhere.  I already have purchased a petcock from Trick Rick (everybody knows him).  Gonna change that and see if that is the problem.  Bike runs good, plenty of power, just crappy mileage.  Started doing that less than 1000 miles ago.

[godfire]

Hey Doc,
Don't mean to sound like a broken record, BUT!
While you have the tank off, consider replacing the vacuum lines and plugs.
The stock Honda lines are known crap.... I picked up 10 mpg by replacing mine......
Good Luck Brother!
gf

[Disco]

Hey Doc,

If you haven't already rebuilt both petcocks and replaced all vacuum lines and caps, I'd start there.      Your pumpkin is 11-12 years old now and Joe's is pushing 8.  The diaphragms, lines, and caps are breaking down.  My 10 year-old bike ran so much better after we did those things to it in December it was like riding a completely different bike home.  Better mileage, too.  The cheapest new motorcycle I've ever had.

All the part numbers for what we did to mine can be found here.

[Hollywood]

well, that's really weird! we have over  77K and  ours is 7 yo, and still get great gas mileage, even with going to 6 deg trigger wheel, let us know what happens.

[Houdini]

Hey Doc and Joe, I have my diaphragm and screen kits and my vacuum hoses are on order; I'd like to join you when you do your bikes or we can do them at my house if you want.  I know my diaphragm is bad; at the synch party my petcock wouldn’t stay open with a pump, it kept leaking down.

I average 33 MPG now so I don’t expect much improvement in mileage but you never know…

[Doc809]

Thanks Verm.  Don't know if I can be at the wrench party Saturday or not.  Will know later in the week.  If not we can get together and get this done.  L