Advice needed on Possible Jetting / fuel issues

[pvonkaenel]

Hi all, I could use a tad bit of help trying to decide where some issues are happening on my 98 tourer. It seems to have decent power up until 4k rpm and then starts to falter. I just purchased this one, it has cobra pipes with the adjustable needles and I am in Colorado at a mile high. The adjustable needles are set at the middle adjustment and it there is also a small washer as a spacer on the needle also. 

The bike also has a whole different petcock rather than the Valkyrie one.

I am trying to see what I might need to do to make it run a bit better throughout the range, rather than falling off the way that it does. 

I appreciate any advice. One thing I have not checked yet was the condition of the airbox. it does kind of seem as though it starts to starve for air or fuel once it gets up into the higher revs.

Any help or advice would be appreciated. Thanks again.

[da prez]

  If I had the bike , I would check for fuel flow. If possible , bypass the petcock. I mean go back to stock. Pull the fuel tank and check the fuel screen. A fuel hose that is to long will kink and starve the carbs.
  Do items one at a time. If you change everything (going into the carbs) then you have not found the problems.
 This statement will start an argument (discussion) , Valks tend to over fuel. A full carb sync and check for vacuum leaks. Be sure all intake tubes are connected. Look for the little things. Do not assume. Check all vacuum hoses as they are often overlooked.
    KEEP us informed please.  There is a knowledgeable Vakkaholic nearby.

                                                      da prez

[Pluggy]

 If I had the bike , I would check for fuel flow. If possible , bypass the petcock. I mean go back to stock. Pull the fuel tank and check the fuel screen. A fuel hose that is to long will kink and starve the carbs.
  Do items one at a time. If you change everything (going into the carbs) then you have not found the problems.
 This statement will start an argument (discussion) , Valks tend to over fuel. A full carb sync and check for vacuum leaks. Be sure all intake tubes are connected. Look for the little things. Do not assume. Check all vacuum hoses as they are often overlooked.
    KEEP us informed please.  There is a knowledgeable Vakkaholic nearby.

                                                      da prez

Can't argue with this.  The easy first step:  The service manual shows how to remove the tank and has diagrams of the fuel and vacuum tubing.  if the previous owner added a filter in the fuel line, those can restrict flow.  All vacuum lines must be soft and correctly connected.  Look where the vacuum lines meet the lower "nipple" as that's where a hose could likely harden and fail.

And while the tank is off, it is easy to check the air filter.  Here's the manual:

https://web.archive.org/web/20220328115011/https://valkyrienorway.com/download.html

[98valk]

follow this.  its running too rich.

http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html

[sandy]

The adjustable needles are not stock. The small washer is both stock and part of the needles that you have. You say "middle" notch. I would reset that to the 2nd notch down from the top. This will leen out the mixture at high altitudes.
Does your petcock have a vacuum operation? If so, replace that vacuum line.

[pvonkaenel]

follow this.  its running too rich.

http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html

What a great resource, I will definitely follow it. Thank you.

[pvonkaenel]

The adjustable needles are not stock. The small washer is both stock and part of the needles that you have. You say "middle" notch. I would reset that to the 2nd notch down from the top. This will leen out the mixture at high altitudes.
Does your petcock have a vacuum operation? If so, replace that vacuum line.

While the petcock it not the stock one, I do believe it has a vacuum line connected to it. I looked around online and this looks like the petcock that is installed. I do plan on getting the actual Valkyrie petcock soon.  Before I dig deep in the carbs I will test some adjustments on those needles and replace that vacuum line since that will be an easy thing to knock out.

https://www.amazon.com/Petcock-Valve-Switch-GL1500C-VALKYRIE/dp/B09NVSZZFS/ref=sr_1_22?sr=8-22

[Hook#3287]

The adjustable needles are not stock. The small washer is both stock and part of the needles that you have. You say "middle" notch. I would reset that to the 2nd notch down from the top. This will leen out the mixture at high altitudes.
Does your petcock have a vacuum operation? If so, replace that vacuum line.

While the petcock it not the stock one, I do believe it has a vacuum line connected to it. I looked around online and this looks like the petcock that is installed. I do plan on getting the actual Valkyrie petcock soon.  Before I dig deep in the carbs I will test some adjustments on those needles and replace that vacuum line since that will be an easy thing to knock out.

https://www.amazon.com/Petcock-Valve-Switch-GL1500C-VALKYRIE/dp/B09NVSZZFS/ref=sr_1_22?sr=8-22

That petcock looks the same as an OEM.

But is it made of Chinisium? Who knows?

It could be made by the same company that makes the OEM, or not.

Maybe the interior rubber is of less quality?

It is cheap money.

[h13man]

OEM petcock is the best if you like the factory setup but a manual Pingel was already on mine when I got it thus I always shut off the fuel regardless the setup. Never know when float valves and/or petcock diaphragm fails leading to hydrolock. Its a crap shoot with the rubber components getting to be 29 yrs. old on these bikes. Manifold o'rings are another fix to address. A lot of good aftermarket parts to be had here:

https://redeye.ecrater.com/category.php

[pvonkaenel]

Update:

So I took the carbs apart and found along the way that the pair valve tube that goes to the middle intake on the right side of the bike (as  your sitting on it) was completely disconnected. I am wondering if that had any thing to do with the high end power.

Also found that someone has definitely been in here before because the Main jet's appear to be aftermarket but they don't have any markings on them at all so I don't know if they are the stock size or not. Partzilla has the stock jets in stock right now for pretty inexpensive so I thinking about going ahead and buying them, unless there is a known jet size that would work better with cobra pipes for 5k feet of elevation. 

If anyone has advice on the right main jet for this application it would be great.

[sandy]

The main jet is a 100.