Gas milage just went to hell

[hueco]

Have always got around 33 to 34 mpg. Highway riding 70 to 80 mph. All of a sudden milage dropped to about 28 mpg. And I have been riding slower. Around 65 to 70. Smells like it is running rich. Nothing else has changed. Still runs the same that it always has. Always put some Sea Foam about every other fillup. 40,000 miles. Always kept inside when not riding. Could a petcock diaphram going bad be the culprit? Any suggestions appreciated. TIA.

[bassman]

M'be a quick check of your tire pressure??  Should be a minimum of 40# front and 42# rear.  I experienced the same problem as you are when my front pressure went from 40# to around 36-37#...Check the simple first....

[Grandpot]

Unless the petcock was leaking gas onto the ground, it would not cause a change in gas mileage.

As stated in the previous post, check the simple stuff first.  Vacuum line leaks, O ring leaks, dirty air filter.  A bad O ring in the carb pilot screw can also cause a vacuum leak. 

[Thunderbolt]

Affects mileage and performance.

[longrider]

Move the choke control on and off and check that the linkage at each carb bank is returning back to the off position.  if one hangs up a bit it will leave the enrichment valves open and use lots of fuel. if you want to see a bit better remove the screws and take off the chrome cover for a better view

warren
5054

[hueco]

Already did the choke check. If it was a vacuum leak I think idle would be going up and down. Or, bad performance. K&N air filter. Have not run the Baja 1000 with it latly. So, filter should not be that dirty. It starts runs and operates the same that it always has just gas milage has took a sh!t.

[DeathWishBikerDude]

Check the ethanol content in the gasoline your using.
I got stuck with some cheap fuel once and noticed spitting and sputtering and reduced mileage.
My secret fuel additive is K1 kerosene.

[Grandpot]

DeathWishBikerDude:

I have read a couple of your posts that mention using K1 Kerosene as a fuel additive.  I thought I heard of everything, but you have me on this one.  Please post the details such as, percentage of mixture, how often do you add it, and what really are the benefits.

Thanks,

Keith

[hueco]

Thanks, everyone for the suggestions. Upon further visual inspection the vaccum line coming off the # 4 intake runner has colllapsed right where it comes off the nipple. Can't tell if it has a hole in it but has definitely sucked down on itself. Looks like vaccum line replacement time. I try to keep a record of parts #s .tips and stuff like that off here. I thought I had the vaccum line size. But, I can't find it. Hint, hint. Thanks.

[Brad]

Thanks, everyone for the suggestions. Upon further visual inspection the vaccum line coming off the # 4 intake runner has colllapsed right where it comes off the nipple. Can't tell if it has a hole in it but has definitely sucked down on itself. Looks like vaccum line replacement time. I try to keep a record of parts #s .tips and stuff like that off here. I thought I had the vaccum line size. But, I can't find it. Hint, hint. Thanks.

Vacuum lines are 3.5mm or 5/32nds

[Airetime]

Thanks, everyone for the suggestions. Upon further visual inspection the vaccum line coming off the # 4 intake runner has colllapsed right where it comes off the nipple. Can't tell if it has a hole in it but has definitely sucked down on itself. Looks like vaccum line replacement time. I try to keep a record of parts #s .tips and stuff like that off here. I thought I had the vaccum line size. But, I can't find it. Hint, hint. Thanks.

http://www.valkyrieriders.com/shoptalk/AirBox%20VentHose/venthose.htm

[hueco]

Thanks, Airetime. Thats going to help a bunch.

[X Ring]

DeSmog!!    You'll never have to worry about it again.  

[DeathWishBikerDude]

DeathWishBikerDude:

I have read a couple of your posts that mention using K1 Kerosene as a fuel additive.  I thought I heard of everything, but you have me on this one.  Please post the details such as, percentage of mixture, how often do you add it, and what really are the benefits.

Thanks,

Keith

I add a few ounces to a full tank of fuel.
When I worked as a mechanic years ago,we used kerosense in the parts washer as a solvent,to break down grease and crud on engine parts.
I wouldn't go over board adding it to the fuel,just a few ounces seems to work well.

[Valker]

If you buy a product at an auto parts store called "5 minute engine flush", I understand it is just kerosene.

[srbarclay]

I add a few ounces to a full tank of fuel.
When I worked as a mechanic years ago,we used kerosense in the parts washer as a solvent,to break down grease and crud on engine parts.
I wouldn't go over board adding it to the fuel,just a few ounces seems to work well.



How does the bike run with kerosene and are there any negative affects to the engine?
Does it improve the mileage much?
Questions, questions, questions.

[borat]

I use Seafoam in the fuel every so often.  It's excellent for internal carb cleaning as well as removing water from the fuel system.  However, all the magic elixirs in the world won't fix bad fuel and vacuum lines. 

[hueco]

Got the vaccum lines repaced today with 5/32" line. It has a thicker wall than the stock line. So should last longer. #4 line did have a split in it. Every thing went well. Except for that friggen air box. Man, want a pain. Thought I might lose it and go postal. Thanks to all. After I run through a few tanks I will give an update on milage.

[BuzzKill]

I encountered the same problem this weekend.  Took a overnight trip a few hundred miles out.  I usually got around 35ish mpg, going to reserve around 130ish.  Was good enough for me.  This weekend I dont think I got over 120 without reserve on 4 fill ups. The times I did check the actually mileage was 26, 26, and the last one I'm guessing is around 23.  Havent gased up cause I'm sure I'll need to take the tank off so I left it empty. 

I'll check the vac lines tomorrow or this week.  Never had to mess with it so will be a learning thing for me.  If I need em, can I get em at any auto parts store?  If so how much total?  Any other ideas?

97 Tourer.
30,000 miles.
Oil and plugs 6k old.
Air filter 2k.
The only thing I've done recently is add some bullet lights.
I dont know how well its been upkept before I got it a year ago.

[hueco]

Any auto parts store should have it. I don't remember how much it took. it is cheap. Get bout 3 to 4 feet. Won't take that much.  After I replaced the lines mileage went back to normal. Have not done anything to it since. VFFV. This will help a lot. For me the airbox is the worst part.http://www.valkyrieriders.com/shoptalk/AirBox%20VentHose/venthose.htm

[John U.]

Vacume lines aren't the only things that can cause a vacume leak.
Also check for black/brown leakage on the top of the heads at the bottoms of the intake tubes, the O-rings will leak eventually. If they are leaking fuel they will also leak air.
The rubber connectors between the intake tubes and carbs have band clamps on both ends which work loose. Same for the clamps that hold the rubber airbox tubes on.

[BuzzKill]

Vacume lines aren't the only things that can cause a vacume leak.
Also check for black/brown leakage on the top of the heads at the bottoms of the intake tubes, the O-rings will leak eventually. If they are leaking fuel they will also leak air.
The rubber connectors between the intake tubes and carbs have band clamps on both ends which work loose. Same for the clamps that hold the rubber airbox tubes on.

I've replaced all the vacuum lines and caps and even some other hoses while I was in there.  I havent gotten the airbox back on yet.  Never done this so its kinda slow as its a learn as you go process for me.  I havent found "the smoking gun" yet, but some of the hoses were a bit brittle and most of the caps were cracked a bit at the openings.

I think I know what your talking about, as I have seen some brown oilish residue on the top of the engine near the plugs.  I dont see it all the time, so I havent thought much of it.  What I dont know, is what O Rings your talking about exactly.  Could you be more specific as to which?  I do have the PDF manual if that would help showing me which ones.

[fat6man]

He is talking about the O-Rings that seal your Intake Runners to the top of the engine Head. Not a very hard job to do just be sure to keep new o-rings in the grooves on the sealing surface of the intake runners. O-ring size is 2.4mm. Diameter x 29 mm. Be sure to use O-rings made of Viton. Should be able to find these on E-bay at a reasonable price.

[X Ring]

He is talking about the O-Rings that seal your Intake Runners to the top of the engine Head. Not a very hard job to do just be sure to keep new o-rings in the grooves on the sealing surface of the intake runners. O-ring size is 2.4mm. Diameter x 29 mm. Be sure to use O-rings made of Viton. Should be able to find these on E-bay at a reasonable price.

Had to quote him so I could change the type color from purple so I could read it.

Marty