running rough on low RPM

[KiroValk]

Hi Guys, bought my 2003 Valkyrie a month ago.It has 5500 mls on it. Above 2200 rpm it is running fine a lot of power, on lower RPM there is some popping. Been reading here a lot ( great site thank you all) and it seems like the slow jets are gummed. Before I take apart carbs I took the spark plugs off and they are all the same,dark and almost wet.The vacuum lines seems fine will change them just to be sure.I ran several thanks with see foam , B12 . It helped some but kinda made the popping on low rpm more noticeable and isolated.
 
My question is if the carbs are gummed should't   it run lean (less fuel more air ) or i'm wrong?

[wirral_biker]

Had exactly this on my 3,500 miler !     Was the slow running jet on number 1 carb which was blocked.
Seafoam wouldn't cure it. In end had the carbs removed and the jet cleaned etc.  Hunky Dory now  :-)
Starting up from cold, you will be able to feel which downpipe is staying cold in order to identify blocked carb.  Good luck !!

[old2soon]

      Full can B-12 ChemTool in full tank of gas. Ride around under or at 2000 RPMs for 20-30 miles. See if that helps. Try the B-12 before pulling carbs. RIDE SAFE.

[TTG53#1717]

I had a problem kinda like that and it finally turned out to be a kinked slide spring that was actually preventing the slide from fully returning home.

I thought it was from gumming up while sitting after I had surgery. I used in tank and spray cleaners with no help. I discovered it when I was doing my fuel rail o-rings and had the carbs on a bench.

On the bike, you have to remove the choke rails ( keep track of spacers ) and then it’s pretty easy to check the slides/springs.

[sandy]

Before taking carbs apart, check the pilot screws. Set them all to 2 turns out from lightly seated. BTW: What’s your MPGs?

[98valk]

Before taking carbs apart, check the pilot screws. Set them all to 2 turns out from lightly seated. BTW: What’s your MPGs?

yep, sounds to rich on the mixture screws.


what exhaust? last time air filter was checked?

[gordonv]

Hi Guys, bought my 2003 Valkyrie a month ago.It has 5500 mls on it. Above 2200 rpm it is running fine a lot of power, on lower RPM there is some popping.

I ran several thanks with see foam , B12 . It helped some but kinda made the popping on low rpm more noticeable and isolated.

I'm the first to suggest the easy method of riding it with chem cleaner in the bike. Sea Foam wont touch what you have, a 5500 mile bike. Do you want to enjoy riding or tear it apart? I would continue the chem cleaner, this time try a different one every time. Techron comes to mind. Also you want to double dose it. I keep saying 1/2 can to half a tank, but if you read it, that's a double dose. After Techron, try something else or the B12 again if you didn't do it strong before.

BUT you have to ride it in the range that it's giving you trouble. So low speed in high gear. That might mean city to winding roads, but you want to use the carb in the rpm range that has trouble.

Your bike has barely reached the first oil change, so it's never been ridden and sound like fuel fouling. So it may take a long time, so go out and enjoy it to the best you can, and wait till your down time to tear into the carbs. There is a lot of how-to out there for that.

[KiroValk]

Thank you all. It seem like wirral_biker was right. I started it cold and the #6 exhaust stayed cold. I can literally hold it with my bare hand. All others are hot.
I will give it some more time with b12, but i have 500mls on it so probably will be cleaning carbs.

Will update.

[Challenger]

If you have narrowed it down to #6 only, you can pull the intake runner and remove the bowl and slow jet without removing the entire carb bank. Beats removing tank and air box. Cleaning a clogged jet is a little difficult but can be done. Mine was plugged so tight I had a heck of a time getting .035 wire through it. No way was any cleaner going to get that slug out. Then keep up the B-12 for a while to make sure the other five all cleaned up good.

[Six Guns]

Try Yamalube ring free additive. One ounce of Yamalube to 10 gallons of gas. I put in 2 ounces of Yamalube into 6 gallons of gas. On line they call it the shock treatment. It took about a week of riding in my neighborhood very slowly before I noticed some good results. After a week of that, I put in a whole bottle of Techron fuel system cleaner in a near empty tank and topped it off with high test Chevron gas with Techron. Rode my Interstate for about a week straight every day and now I can start my valk up without using the choke. That is what worked for me. Your results may vary. Do this at your own risk to your valk. I had to try something because my valk would die as soon as I turned off the choke. I am happy with the results.   

[KiroValk]

Hi guys, I opened the #6 while on the bike (thanks Challenger). Wasn't hard at all. I expected to be real dirty, but it was not, just a drop  or two on the bottom of the boll . The slow jet was somewhat plugged, I could hardly see a light through it. Sprayed it whit a carb cleaner I now see a bigger hole still very small.
Did'n spray through the jet seat in the carb because was not sure if carb cleaner would reach rubber .

Well It runs a little better still not right. I will ride it some time hopefully it will clear. Probably will take out carbs to clean them anyway it's not so hard.

[98valk]

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

[Jersey]

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

That's a great link.  Have used it before and really helps.

[KiroValk]

Happy 4th of July to all.
Little update on my issue. I took out the #6 spark plug after idling for a min and it was wet. So  if  the pilot passage is plugged should the spark be wet? I swapped th #6 and #4 plugs and i had a running #6 and cold #4. There was a lot of smoke for a min or so. I'm waiting on the spark plugs to arrive today at advance auto parts ( its open on the 4th!!).
It will turn out it was a bad plug, and I could hear clicking when taking out the plug while engine running so I assumed there was a spark.
Thank you all for the advices

[John Schmidt]

Suggestion for the future; don't remove a plug to test while running the engine. Use a spare spark plug and leave the other one still in the motor. You'll still get a go/no-go on spark and if you can draw that spark out 1/4" or more you have a good one.

[KiroValk]

I haven't remove the plug it's self , just pull the cable while running and could hear clicking , so I assumed there was spark. Now when I thing of it, it was spark between the cable and the spark plugs.