Hesitation at 3000rpm...

[Marcus De Grate]

Good day all 

I am new to Valks, as in just a mere 2,500 experience miles into my first one!

Its a 2000 US Tourer model.

It is due a 24,000 mile service, which I intend to do over the week of the 16th September when I am "working" from home for a week, but I doubt my niggle will be resolved by a service.

When moving at almost exactly 3000rpm the bike has a flat spot. It is so slight through gears 1-3 that I am half convinced I am imagining it, but in 4-5 there is an acceleration drop off, that picks up again about 4000rpm. I know its not a great test, but  if I whack the throttle open in 4-5 at around 2000rpm, the needle shoots  up to 3, slows down to 4 and then we are off again.

Using the choke while in this rev range makes the bike sputter and stall and opening the gas tank filler makes no difference whatsoever.

Aside from the usual service items I am going to check all hose connections/condition rebuild the petcock, ultrasonic bath the carbs, balance and then scratch my balls wondering if that's solved it while I put it back together. 

I was wondering if anyone would have any other suggestions or experienced a similar issue so I can get the bits in in advance.

[Leathel]

Run the bike at that rev range for a bit, hit the kill switch and coast to a stop, pull and check the color of the plugs.... might give you an idea if its rich or lean.

Mine was rich after some tweaking....but I am waiting for bits for mine (UK model and had much smaller jets & a different needle than the US models)

[DeathWishBikerDude]

Valve adjustment.big difference after a correct tweaking.

[Hook#3287]

A 17 year old bike with 24k on her?  Looks like she sits some.

I'd try some non-corn gas with a heavy dose of B-12 first, maybe a couple tanks.

[Blackduck]

Any history on the bike? Like after market needles.
That rev range is mostly the needles, sounds like it is lean then picking up as the air filter design enriches the mixture.
As already said a couple of good doses of carb cleaner would be a good start.

Leathel what numbers are on your needles?

Cheers Steve

[Marcus De Grate]

Yes, I'll grab some B12 from the store and give it a run round, plenty of time before the 16th to give it a good dose.

History is a bit sketchy - From the 8000mile service the gentleman had done it all himself based on the recommended service schedule. It had been doing very low miles because the owner was old and not in the best of health (He has had it since new). Sadly his health has just failed him so he sold this to me as there is no chance of him ever getting back on it now.

I have done more or less 2,500miles on it in the last 6 months and I never really noticed the issue until about a month ago. It hasn't got better or worse in that time, so perhaps it was there all along and I just didn't notice its faults because of the honeymoon period.

He told me that the bike is completely standard; I haven't taken it apart myself yet but no reason to think that it isn't running the original needles. I imagine its a bit gummed up in there but...

[Chrisj CMA]

A 17 year old bike with 24k on her?  Looks like she sits some.

I'd try some non-corn gas with a heavy dose of B-12 first, maybe a couple tanks.

This is what I would do as well

[Marcus De Grate]

Just to clarify, when you say heavy dose, what exactly do you mean?

[Chrisj CMA]

Just to clarify, when you say heavy dose, what exactly do you mean?

If full or almost full tank put half a bottle in.  That's if you are using the Chemtool B12.  Techron or seafoam doesn't work as well you would need to use more.  That's what I like about the Chemtool

[Ricky-D]

3000 rpm's doesn't really indicate much at all. Throttle setting is what's important when dealing with troubles like yours. The first thing to do would be to index your throttle. You also need to indicate any changes to the exhaust system. Thirdly would be to check and correct any vacuum leaks. With the throttle indexed you can then indicate the throttle position at which the problem occurs.

***

[Marcus De Grate]

I'll get the crayons out later and mark the throttle positions... It is over 1/2 which I assume is main jet territory, but its odd that the low gears are hardly affected at all.
The bike is absolutely standard to the best of my knowledge. OEM everything including the Exhaust.

[longrider]

What are the pilots set at. They should be 2 1/4.  If they are lean you may get a flat spot as the carbs transition to the mains.  Also a carb sync should be done at the same time

[Bagger John - #3785]

Might also want to look at cam belts on a bike as old as yours.

My '99 Tourer got the belts changed year before last; the originals were still in place. The bike only had around 12Kmi on the clock before the swap.

I didn't realize it but there previously was a flat spot in the power band, around the area where the bike runs at freeway speeds. That is now gone.

[Hooter]

I agree with Chris.  Chemtool, B-12 next couple of tanks  full. 1/2 can each full tank. Start simple, don't take the motor out yet! If that (the B12) doesn't work come back HERE and let us know.

Make sure your intake boots are good and snug.

[gordonv]

And run the engine in the rpm range that you feel the problem is in.

[The emperor has no clothes]

My opinion is 99% of the time it's clogged slow jets. I hope the B12 does it. I tried 3 tanks of heavy Techron with no luck. Removing the jets and cleaning them and the carbs is what it took for me.

[Crackerborn]

Some one will correct me if I am wrong but 3k is where the low speed jets are switching over to the mains. I agree with the B-12 treatment as a first step, maybe even several tanks just to be sure. I would also recommend draining the bowls to see if there is any evidence of strange matter that has settled in them. The bowls can be dropped and cleaned on the bike if they appear to be full of sediment. If the B-12 helps, then proceed to the pilots and sync. Vacuum lines are always a source of problems when old and cracked, I remove and replace them when I get an older bike, whatever the make.

[Marcus De Grate]

Thanks everyone, I really appreciate the suggestions.

[Ricky-D]

While throttle setting controls the rpm's of the engine, the rpm's of the engine are not an indication of the throttle setting. Pretty simple when you stop to think about it.

The only way to properly analyze carburetor problems, "Off Idle",,, is to index the throttle.

Carburetor problems are only carburetor problems, when you have assured there are no vacuum leaks, and fuel is available in the carburetors.

***

[Blackduck]

Ricky-D,
Care to explain how indexing the throttle is going to solve carby problems?

About the only "Proper" way to analyze problems is on a Dyno with a good exhaust gas analyzer.

And if you re-read the original post he has the problem at both fixed rpm and when whacking the throttle open. You don't need indexing to tell you it is wide open.

[Blackduck]

Then again if you want a continuous check on your mixtures you could grab a couple of these, weld the fittings into the pipes and you are in business.
Real time, real conditions.
http://www.innovatemotorsports.com/products/mtxl_plus.php

[Marcus De Grate]

Then again if you want a continuous check on your mixtures you could grab a couple of these, weld the fittings into the pipes and you are in business.
Real time, real conditions.
http://www.innovatemotorsports.com/products/mtxl_plus.php

Nice find there sir; but wouldn't I need to have six of them to set it up correctly? Would look quite a doozy on my bars though 

[Ricky-D]

Ricky-D,
Care to explain how indexing the throttle is going to solve carby problems?

About the only "Proper" way to analyze problems is on a Dyno with a good exhaust gas analyzer.

And if you re-read the original post he has the problem at both fixed rpm and when whacking the throttle open. You don't need indexing to tell you it is wide open.

Not trying to be argumentative here, but maybe you should actually go back and read his post again. Your statement smacks of failed comprehension of what he wrote. And, if you cannot understand why indexing the throttle is necessary when trying to solve carburetor problems, well, I certainly would not ever recommend you to work on any motorcycle, to anybody.

***

[Blackduck]

I comprehend what he wrote, that is there is a flat spot around 3000 rpm.
Full throttle from 2000 slows at 3000-4000 then picks up again.
FULL throttle.
He did not state how much throttle he was using going through 3000 in the gears but had to be some as you will not have a flat spot with steady throttle.
Indexing works with cable actived carbs as you will know where the slide is, with vacuum operated you are still guessing where the slide will be for a given throttle input.

As I said 3000 is needle territory, slows/primary system also affect this area and would be the most likely culprit.
When the rpms go over the 3000/3500 mark the standard air box starts to restrict the air flow and acts as a choke enriching the mixture.

[Hooter]

Is it fixed?

[Marcus De Grate]

Not yet buddy...

I am running a few heavy dosed tanks of B12 before I get the chance to pull it apart and play with it; which will be w/c 16th Sep. I have just noticed my fuel line is about 10 inches long with a great big bend in it and an additional shut off valve installed; so someone before me has altered that; I'll be changing that back to standard too...

[The emperor has no clothes]

Not yet buddy...

I am running a few heavy dosed tanks of B12 before I get the chance to pull it apart and play with it; which will be w/c 16th Sep. I have just noticed my fuel line is about 10 inches long with a great big bend in it and an additional shut off valve installed; so someone before me has altered that; I'll be changing that back to standard too...

That fuel line could be the whole problem.

[kristoffair]

Marcus
I had a similar problem, it was due to the piece of foam fixed in the lid of the air box falling apart.
It's a UK model so I'm not sure the USA models are the same but it's worth a look as it's an easy fix.
I replaced the foam with a similar sized piece and it transformed the bike, now runs really smooth.
Cheers,
Chris.

Just got to pull the engine now over the winter to fix the starter after the dreaded Hydro-lock!!

[Hooter]

I think stock fuel line is only 8.5 inches long. Like Meathead said, could be it?

[Blackduck]

Chris, US bikes don't have the foam pad.
Your other option with a failed pad is just delete and add 100 mains.
Cheers Steve

[kristoffair]

Thanks Steve,
I may change the jets when I have the engine out to fix the starter over the UK winter.....can't wait!

[Paladin528]

the fuel line does not explain the problem.  sounds like you have a Dan-Marc valve in there.
if it were the fuel line then the issue would get worse at higher RPM.  on my I/S with the Dan-Marc installed I will typically lose power after running at 85 MPH for about an hour.  That is how long it take for the restricted fuel to finally be low enough in the carbs to cause power loss.  Slowing down rectifies the issue in short order.  I could run 3000 RPM all day long with no issues.

[Leathel]

Chris, US bikes don't have the foam pad.
Your other option with a failed pad is just delete and add 100 mains.
Cheers Steve

and swap out the needle for a US one (UK is shorter and will run rich with 100's)
Also open up the pig tails as they are also half the size to the US ones

[Blackduck]

Leathel,
Do you have the number off the UK needles?
I have 2 different needles but they are both the same length, only shorter one I have seen as aftermarket.
Cheers Steve

[DeathWishBikerDude]

You guys and carbs are killing me.
Carbs rarely go bad,its usually other issues.
Carbs should be the last items adjusted and or modified.

[Hook#3287]

You guys and carbs are killing me.
Carbs rarely go bad,its usually other issues.
Carbs should be the last items adjusted and or modified.

You do realize they are talking about changing the UK carbs (and airbox & exhaust) to the US standards?

The carbs on Valks are excellent and should last for decades as built, but, that was before the 10% crap gas was forced on us.

As stated in earlier posts, the carbs design included using 10% corn.  I think the engineers didn't realize how it would plug up the orifices of the jets, if the gas sat in the carb for as little as 2-3 weeks.

I have changed out all my slow jets to 38's and I understand there is belief that may cause some carbon build up, but I have yet had to pull any carb due to clogged jets.

[Hooter]

I carry Barrymans with me. When traveling I add a dose every 3rd tank or so.  Never have had a carb issues. I store with Sea Foam. And yes, the carbs do gum up and make the bike run like crap some resulting in rebuild if left unattended or treated for too long.

[Ricky-D]

The belief that #38 slo-jets will solve the problem is wrong-headed. The reason that those, who have changed to #38 slo-jets no longer have problems is because: They have learned how to treat their bike properly. They could go back to #35 slo-jets and not experience problems again. It is all because of how you treat your Valkyrie.

***

[Hook#3287]

The belief that #38 slo-jets will solve the problem is wrong-headed. The reason that those, who have changed to #38 slo-jets no longer have problems is because: They have learned how to treat their bike properly. They could go back to #35 slo-jets and not experience problems again. It is all because of how you treat your Valkyrie.

***

Ricky, I understand that's your opinion, but I can only relate my experience.  I don't put additives in my gas.  I don't use Berrymans or Seafoam ever.  Damn bottles leak all the time.   I treat my gas at the end of the season with Stabul Marine and park the bikes. 

One of my bikes has been running 38's since 2008 and the others since 2013, and 2015.

All of them run excellent and all of them start in the spring like I put them away the week before.

I've never had the carbs apart since.

On another note, I'm in the middle of mounting a C/T and it has two dots on it.  A red and a yellow.  I didn't know which to mount next to the valve.  Did a search and you helped me out.

http://www.valkyrieforum.com/bbs/index.php/topic,12499.0.html

Thanks.