Sudden lack of power...

[rayvin57]

Yesterday I had added a full can of seafoam to an almost full tank, hoping to really smooth out my Valk at the lower revs, although the bike ran very well anyway.  Looking for perfection, I guess.  Turns out it may have been a bad move on my part--this morning, it started right up (although I noticed a little black exhaust at first), and idled fine while warming up and ran fine down to the end of my street, but when I accelerated (2 up, btw) onto the main drag off my street, there was a sudden loss of power, complete with exhaust popping.  I ran the bike for a while, hoping I just had to run the seafoam out of the gas, but it's definitely running on only 3 or 4 cylinders.  Guessing it's electrical, like maybe a coil went on me, since I'm getting lots of popping and assuming gas is still flowing to all carbs.
I know I've got to check spark at all the plugs, but any advice would be appreciated.
Thanks.
Vin

[Valker]

Open the fuel tank cap (use an extra key and leave it slightly open) and see if it runs ok then. If so, the vent line is kinked/plugged.

[salty1]

Sorry to hear about your problem! I'll bet your carbs are "gunked" up. That Seafoam probably suspended some sludge and plugged/restricted your low speed jets and maybe some of the high speed jets as well.

[olddog1946]

Turn the petcock on

[R J]

Turn the petcock on

I 2nd that.

[Patrick]

When you added the Sea-foam, was it before or after the gasoline ? Make sure whether you have good fuel delivery or not and then if you have ignition/spark to all cylinders and see if you can determine which cylinders aren't working. I doubt you have an ignition/electrical issue.

[whitestroke]

Was Seaform added to a fresh tank or a stale tank of gas?

[salty1]

Sorry to hear about your problem! I'll bet your carbs are "gunked" up. That Seafoam probably suspended some sludge and plugged/restricted your low speed jets and maybe some of the high speed jets as well.

Just did a complete carb cleaning a month or so ago and it was running well right up to this morning.  It was a very sudden loss of power when it went--I'll test for spark and fuel delivery tomorrow. Petcock is on  .  Seafoam added to fresh gas, just about a full tank.  Got a feeling it's not a fuel problem.  It's  like it's running on 3 cylinders--and if you give it gas too quickly it chokes up.

Still sounds like a fuel issue. 

[Hoser]

Didja try what Valker said?  Hoser

[custom1]

Could be a bad vacuum line from #6 to the petcock, or the vacuum diaphragm in the petcock going bad. Sucking air and allowing the petcock to partially close. It will run ok at low load but is starving at high load.

If you have a mighty vac, pull a very slight vacuum on the vacuum line from #6 and see if it holds or leaks down.

Did you happen to add a fuel filter or quick disconnect when you had the carbs out?

[Beer van Huet]

With the F6C (export version) this sounds familiar. If your loss of power occurs above approx. 3500 RPM and you have black smoke and it looks like the engine is running on 5 cilinders, take a look at your airfilter cover. We have had more than a dozen same ocurrences now, where the pre-filter (small piece of foam, glued to the cover air intake top part) has deteriorated. Engine immediately responds and will not accelerate without this s@#$%id piece of foam.  Prefilter does not sell separately and is permanently attached to the airfilter cover.
If the (US) Valkyrie has a different airfilter cover, disregard this msge.

[Patrick]

Since we just found out that you had the fuel tank off recently, it could very well be a kinked vent line. Its a common problem.

[Patrick]

Some like rebuilding the original petcocks, some prefer the after markets [Pingle]. I'm of the latter persuasion along with an in-line filter.

[Chrisj CMA]

With the F6C (export version) this sounds familiar. If your loss of power occurs above approx. 3500 RPM and you have black smoke and it looks like the engine is running on 5 cilinders, take a look at your airfilter cover. We have had more than a dozen same ocurrences now, where the pre-filter (small piece of foam, glued to the cover air intake top part) has deteriorated. Engine immediately responds and will not accelerate without this s@#$%id piece of foam.  Prefilter does not sell separately and is permanently attached to the airfilter cover.
If the (US) Valkyrie has a different airfilter cover, disregard this msge.

The US version does not have that foam piece

[R J]

Whenever MGM is going to set for a period of time, he gets a FULL can of SeaFoam.

I then run it below 2,000 RPM till I'm sure the SeaFoam mixture is in the carbs.

Then  park it.

When I take it out later, I burn the SeaFoam out with the gas, and try to stay under 2.500  RPM.       This way I'm getting SeaFoam in the small/idle circuit of those 6 gobblers..

SeaFoam is not going to do any harm to the engine, carbs, vacuum lines.    All it will do is make a small dent in your HIND pocket.

It has almost doubled in price since I 1st started using it.

We even use it in Used vehicles we know might set for a long period.    Easier to pour a can of SeaFoam in than to rebuild a carb or injectors.

Sorry about that statement, I keep forgetting, no $$$$$ goes in my pocket anymore since my son bought me out.

[rayvin57]

Just checked and I've got spark to all 6 cylinders. Another sign that 2,4, and 6 are not firing is that I pulled the wires from them and the engine runs the same.  Pulling any one of 1,3 or 5 and it stalls.  So I'm running with just the right side, spark is good all around, gas is flowing from the petcock freely.  Next going to pull the tank again and check the pair valve and vac connections.

[rayvin57]

Finally found the cause of running with half an engine---the throttle linkage from the right carb bank had popped off the left side (cotter pin must've broke or come off).  No wonder the power loss was so sudden.
Got to pick up a tiny cotter pin as I can't seem to find one that small in my little collection, but all is right again with my fat lady.  What's pretty impressive is that I was able to ride about 15 miles home, 2 up, on only 3 cylinders...
Thanks again to everyone for the help.  Those who thought it was a fuel problem were spot on.

[salty1]

Finally found the cause of running with half an engine---the throttle linkage from the right carb bank had popped off the left side (cotter pin must've broke or come off).  No wonder the power loss was so sudden.
Got to pick up a tiny cotter pin as I can't seem to find one that small in my little collection, but all is right again with my fat lady.  What's pretty impressive is that I was able to ride about 15 miles home, 2 up, on only 3 cylinders...
Thanks again to everyone for the help.  Those who thought it was a fuel problem were spot on.

Congrats! Can't keep a good lady down long.   

[Patrick]

Hmm, well, thats a first. That'll have to go in the memory bank. Good to see it back to its old self though.

[Chiefy]

Glad you found it.  Glad you shared it too.

[rayvin57]

Hmm, well, thats a first. That'll have to go in the memory bank. Good to see it back to its old self though.

Yeah, still can't figure out how the cotter pin came off.  The two small washers that go on before the cotter pin were just sitting beneath the linkage, on top of the engine block.  I should have noticed the pin missing when I pulled the carbs in November.  I can't see this being a common occurence, that's for sure.

[custom1]

Glad you found the problem.

To answer a couple of your questions.

Too much cleaner in the fuel cannot effect the vacuum diaphragm because.....
The fuel never touches the vacuum diaphragm unless the fuel side diaphragm is bad. If the fuel side is bad fuel should be dripping from the weep hole on the bottom.

Also both diaphragms have too be bad to allow fuel to be sucked down the vacuum line to the #6 carb. I'd say this is rare but possible, but you would have fuel dripping out the weep hole as a hint that there is a problem.

Personally, I would not leave the petcock modified indefinitely. If the manual side fails to seat (they have been known to do that), or you forget to turn it off you are relying on the six float needles to prevent hydro-lock.

Either rebuild the factory petcock or put in a Pingle and remember to shut it off every time. I like the factory petcock because it is actually two shutoffs in series. Plus the Pingle changes the amount of reserve you have (unless you lengthen the tube) and then you have filter issues. If you add an inline filter make sure to not have a dip in the fuel line.

Research the options and make your own decision.

[rayvin57]

Glad you found it.  Glad you shared it too.

Hey Chiefy--Yeah, it's good to have the bike running sweetly again--damn, I was down for almost a day!
I saw you had to replace part of your rear end--the splines were shot, eh?  That's on my to do list--got to check on mine.  Even though it's only got 11k on it, it's 10 years old.
How's the riding up by you--snow birds everywhere down here.  Makes riding much more 'entertaining', wouldn't you say? Keeps me on my toes, that's for sure.

[Chiefy]

Glad you found it.  Glad you shared it too.

Hey Chiefy--Yeah, it's good to have the bike running sweetly again--damn, I was down for almost a day!
I saw you had to replace part of your rear end--the splines were shot, eh?  That's on my to do list--got to check on mine.  Even though it's only got 11k on it, it's 10 years old.
How's the riding up by you--snow birds everywhere down here.  Makes riding much more 'entertaining', wouldn't you say? Keeps me on my toes, that's for sure.

Yeah, snowbirds everywhere.  Forget a ride by the beach.  The back roads out by Myakka stay pretty clear though.  Rarely see cops out there either 

[Patrick]

You don't like us snow-birds ?!

[Chiefy]

You don't like us snow-birds ?!

I don't like the crowds/congestion.

[9Ball]

I see you're selling your bike.  What are you replacing it with?

Inquiring minds...I see you finally got all the bugs worked out and now it's for sale.

Good luck with whatever is next.

[rayvin57]

I see you're selling your bike.  What are you replacing it with?

Inquiring minds...I see you finally got all the bugs worked out and now it's for sale.

Good luck with whatever is next.

Thanks, JR.  Just bought a beautiful, black cherry Yamaha Roadliner with Corbin fleetliner bags and fairing, and an FJR 1300 top case that fits like it was made for it. I pick it up tomorrow.
 Reasons for going with a v-twinkie?  I got a taste for the v-twin characteristics with my last bike, a Vic Kingpin, and I missed the rumble and low end torque when I traded it for the Valk.  Although I love the fat lady, especially for burning up the highway miles, most of my riding is 2 up, fairly slow cruising.  The Liner gives me back the low end grunt, the wife loves the color, and EFI is a big plus (I won't miss playing with the carbs on the Valk).

[9Ball]

I see you're selling your bike.  What are you replacing it with?

Inquiring minds...I see you finally got all the bugs worked out and now it's for sale.

Good luck with whatever is next.

Thanks, JR.  Just bought a beautiful, black cherry Yamaha Roadliner with Corbin fleetliner bags and fairing, and an FJR 1300 top case that fits like it was made for it. I pick it up tomorrow.
 Reasons for going with a v-twinkie?  I got a taste for the v-twin characteristics with my last bike, a Vic Kingpin, and I missed the rumble and low end torque when I traded it for the Valk.  Although I love the fat lady, especially for burning up the highway miles, most of my riding is 2 up, fairly slow cruising.  The Liner gives me back the low end grunt, the wife loves the color, and EFI is a big plus (I won't miss playing with the carbs on the Valk).

Love that color.

When I was shopping for a second bike in '05 I was seriously looking at the Roadliner but ended up with a new Midnight Warrior instead.  Ultimately I decided on the smaller, more nimble hot rod which the Warrior fit to a "T".  I sold my Warrior to my son after I bought an '07 Rocket 3....much more power and a lot smoother.

My Wife (then girlfriend) wanted the black cherry V-star 1100, but there were none available in the area.  She ended up getting a new black '05 VTX 1300 instead.

Enjoy the Yamaha and good luck with the sale...