low gas mileage on 98 tourer

[doubleminded]

I posted this on the other valkyrie site,thought our texas one had a tech section and i was on it but wasnt.Today my 98 tourer ran out of gas with only 99 miles registered on the odometer.My wife came to the rescue with some lawnmower gas,a little less than a gallon, and the bike held 4.2 more after riding 2 blocks to the gas station,so i guestimate i got 99 miles on 5 gallons of gas.20 mpg?It has cobra six over six pipes,dont know about jetting,have only owned the bike about 3 weeks.

I know valks get about 30-35 mpg normally, and i expect to get about 120 before going on reserve,but i was riding the whole tank on the reserve setting.I went to the de.aler and he said try riding it in the on position.That helped me a lot?It doesnt smell like gas,it runs perfectly, i got on the throttle very little,only upto 75 mph a few times.My wife followed me home and she said what are those tubes hanging down.Under the bike is a canister,probably some sort of pcv system canister,and the tube came down from one spot on the end of it, then y's into 2 separate tubes.They looked like gas breather tubes,and hung down a lot as if they had been connected to something,but no obvious place to reconnect them was seen.The service guy popped the one connected end of the canister and said maybe it was a california bike and didnt see the need for them.Input appreciated.I really love this bike,maybe the running on reserve thing showed some petcock problem that occurs when in that setting? All help appreciated.Turning the pilot screws out 2 1/2 turns,raising the needles a notch i think it was suggested,go to cobra site,etc.I know you all know the answer,thats why i came here for advice.

[laserpat]

sounds like your pickup tube strainer is clogged or malfunction of petcock. Poor mileage could be a vacume leak or riding into a strong headwind can lower mileage or riding the bike hard will also lower mileage.

[Valkpilot]

As others have suggested, what you experienced isn't unusual at highway speeds in the wind.

But there are some other common possibilities.

1. As mentioned on the Tech board, your air filter should be checked.

2. Your petcock should be checked and probably be rebuilt. Age and miles both play a part in the diagphram failing.  Poor mileage is one of the symptoms of a failing petcock.  The fuel screen in the tank should be replaced at the same time.

4. Make sure all the vacuum lines from the carbs (and the little caps) are intact and do not have any holes or cracks.  Ditto for the lines leading to the pair valves (some of that sissy EPA stuff.)  Also make sure that all the little band screws on the intake tubes are tight.

3. Rejetting for Cobra 6 x 6s is notorious causing a rich-running condition.  I believe this was also mentioned on the Tech board.  Doc809's son struggled for a long time with mileage in the low to mid 20s on a Valk with Cobra 6 x 6.  Finally had the jetting checked and that was the culprit.


My money is on the petcock for the win and the jetting for the show.

[RainMaker]

My I/S is a California model and it has a lot of extra plumbing, including that canister which has mysteriously disappeared, sometime around when the centerstand was installed.

My money's on the petcock and the jetting.  Doc (Larry) has a post about a guy he uses that fixed his son's mileage problems with the cobras.  Sounds very similar.

http://www.valkyrieforum.com/bbs/index.php/topic,29687.0.html


RM

[Doc809]

We found that Cobra's recommended settings for the needles are two clips too rich.  Whoever put the Cobra's on probably went with the instructions in the Cobra rejetting kit.  That may be fine for Cobra but it's not fine for the Valk.  Lean out the needles by two clips.  We got a eight to ten mpg increase with no reduction in power.  If you need information concerning the guy who did the work for us just pm me or go to the thread titled "bike shop info (Ghillie). Larry

[Rocketman]

As others have suggested, what you experienced isn't unusual at highway speeds in the wind.

But there are some other common possibilities.
2. Your petcock should be checked and probably be rebuilt. Age and miles both play a part in the diagphram failing.  Poor mileage is one of the symptoms of a failing petcock.  The fuel screen in the tank should be replaced at the same time.

How can the petcock be a culprit in low mileage?  I can understand how it would be a culprit in acting like it's running out of fuel when it's not, but actually consuming it faster?  Would that be caused by low flow resulting in a lean running, thus low mileage?

[RainMaker]

As others have suggested, what you experienced isn't unusual at highway speeds in the wind.

But there are some other common possibilities.
2. Your petcock should be checked and probably be rebuilt. Age and miles both play a part in the diagphram failing.  Poor mileage is one of the symptoms of a failing petcock.  The fuel screen in the tank should be replaced at the same time.

How can the petcock be a culprit in low mileage?  I can understand how it would be a culprit in acting like it's running out of fuel when it's not, but actually consuming it faster?  Would that be caused by low flow resulting in a lean running, thus low mileage?

It didn't make sense to me, but I replaced the petcock in my son's tourer and the mpg has returned back to what it was.  That was a side effect, in my opinion, of the "running out of fuel when it's not" fix I was trying to effect.  Had no idea it would affect mileage, but it did.

I'm sure there is a reason behind it, but I just took the advice from various postings, did what was recommended and it's fixed.

[Valkpilot]

As others have suggested, what you experienced isn't unusual at highway speeds in the wind.

But there are some other common possibilities.
2. Your petcock should be checked and probably be rebuilt. Age and miles both play a part in the diagphram failing.  Poor mileage is one of the symptoms of a failing petcock.  The fuel screen in the tank should be replaced at the same time.

How can the petcock be a culprit in low mileage?  I can understand how it would be a culprit in acting like it's running out of fuel when it's not, but actually consuming it faster?  Would that be caused by low flow resulting in a lean running, thus low mileage?

It's because the petcock delivers fuel incosistently when it is failing.  Some carbs don't get enough, some get more than they can use and it essentially goes down the exhaust drain.  When it happened to me, half the plugs were white-lean, half were soot covered to the point they wouldn't fire.

Daniel explains it here: http://www.valkyrieforum.com/bbs/index.php/topic,27755.0.html

[doubleminded]

As others have suggested, what you experienced isn't unusual at highway speeds in the wind.

But there are some other common possibilities.

1. As mentioned on the Tech board, your air filter should be checked.

2. Your petcock should be checked and probably be rebuilt. Age and miles both play a part in the diagphram failing.  Poor mileage is one of the symptoms of a failing petcock.  The fuel screen in the tank should be replaced at the same time.

4. Make sure all the vacuum lines from the carbs (and the little caps) are intact and do not have any holes or cracks.  Ditto for the lines leading to the pair valves (some of that sissy EPA stuff.)  Also make sure that all the little band screws on the intake tubes are tight.

3. Rejetting for Cobra 6 x 6s is notorious causing a rich-running condition.  I believe this was also mentioned on the Tech board.  Doc809's son struggled for a long time with mileage in the low to mid 20s on a Valk with Cobra 6 x 6.  Finally had the jetting checked and that was the culprit.


My money is on the petcock for the win and the jetting for the show.

thanks for the input.you sure know and all of you sure know a lot about these bikes

[bassman]

All of the above and also check the air in the tires....s/b at least 40# front and 42# rear....

[doubleminded]

so, do i have to take the carbs off to change the needle settings?Do ihave to tank the tank off to do some of the other things?

[5_19]

so, do i have to take the carbs off to change the needle settings?Do ihave to tank the tank off to do some of the other things?

No you don't have to take the carbs off. You have to take the chrome cover off that is held on with 3 screws.

Here is the link to Rattlebars  http://www.rattlebars.com/mtz/shims.html
You don't need to to do step one and two. After you remove the tops use one off the screws to remove the needle from the slide. If your needles are the one from Cobra they will have 5 grooves in them. Move the clip to the highest groove and repeat 6X

[doubleminded]

so, do i have to take the carbs off to change the needle settings?Do ihave to tank the tank off to do some of the other things?

No you don't have to take the carbs off. You have to take the chrome cover off that is held on with 3 screws.

Here is the link to Rattlebars  http://www.rattlebars.com/mtz/shims.html
You don't need to to do step one and two. After you remove the tops use one off the screws to remove the needle from the slide. If your needles are the one from Cobra they will have 5 grooves in them. Move the clip to the highest groove and repeat 6X

Thank you thank you thank you.Thanks to all of you.I told my wife i had always wanted a valkyrie.She said she had heard me say that about other bikes.Yes i said i wanted a harley.yes i wanted a goldwing,etc.But what i really wanted was a valkyrie,only i only htought so,now i know so.