New member, long story -carbs

[rogerthat]

Ok, glad I found the board and hope you will indulge me.   Also, Hi everybody- I'm Roger.  I have a '97 standard.  I have carb issues and I'm gonna give all the info I have so you can more accurately laugh at me.

I had a carb job done at a local dealer early last year to solve idle/rough mid-range performance.  Bike ran fine afterward for a few months but started to get rough again.  Also started leaking gas onto the cylinder head.  I decided to do it myself this time.  I did a compete carb overhaul meticulously by-the-book.  I replaced all of the O-rings and found that the dealer had pinched a couple of them causing the gas leak and vacuum leaks.  Cleaned the gunk out (ask me what I think of ethanol-- but do it from a safe distance) and reassembled it all and put everything back like it's supposed to be.  The bike started and idled ok, but slow and rough.  I Fabricated an oil manometer and got what I think is balance between the carbs.  Thing is, I can't get any further.  I have terrible idle and can't seem to adjust it.  The idle adjustment speed is inconsistent and the return to idle is really slow.  It seems to be running on three cylinders based on exhaust temps.  I fabricated an idle screw adjuster and think I'm getting movement on the idle screws, but nothing I do gets the dead cylinders to fire.  I don't want to take it back to the incompetent dealer, but I'm having no luck with the final tuning.  Any suggestions?  Go jump in a lake? (please specify lake)  Get a BigWheel? 

Thanks for any ideas.

[Thunderbolt]

I had one cylinder not firing and was able to get enough carb cleaner through it after removing the air box to get it cleaned out.  I'm pretty sure the ethanol cleaned everything out of the tank and lines and dumped it in the slow jets.
The idle is set by one knob/thumbwheel between cylinders 1 and 3, it is usually a gray or black knob upside down.  Turn the knob clockwise to increase idle.
If you are referring to the upside down "d" shaped screws underneath each carb, those are the pilot jets, they come in right after the slow jets.  Might as well take it back apart and remove them and clean out all the orifices.  Just be careful, they have lots of small pieces and parts in there.  Set them to somewhere bwtween 2 and 2 1/4 turns out.  I set mine to 2 1/4.  I think it was motion pro that sells a pilot tool. 
Keep running Sea Foam or Techron in the fuel to help clean out the junk.

[rogerthat]

Oops.  To correct, I did mean pilot jet screws, not idle jet. 

[BudMan]

Yours sounds like what happened to me.  In my case it was just the slow speed jets that were gooped up.  We just  dropped the bowls, cleaned the jets, and it has been good to go ever since.

[98valk]

replace petcock diaphragm and intake manifold o-rings

[rogerthat]

Ah, for my knowledge, how would the petcock diaphragm cause the issue?

The intake Orings are brand new, and the rebuild included cleaning the entire carb assembly piece by piece.  I drained the tank during the rebuild and wonder if the slow jets could have become blocked again in such a short time?

Thanks for the input.

[Mr. Nuts]

If you just cleaned the slow jets and didn't replace them, my bet would be that they are still not completely clear. The orfice is so tiny it is difficult to tell when they are fully open.

[BudMan]

I drained the tank during the rebuild and wonder if the slow jets could have become blocked again in such a short time?

Mine did.  I had the tank off for a d-smog.  Put it back together, and they were plugged.  I suspect moving and shaking the tank loosened a bunch of gunk.

[rogerthat]

Ok, looks like slow jets are the place to look.  Guess I can disassemble it again and check.  And on this note, whats is the best way to clean out the gas tank?  Any cool chemicals that will get the gunk loose while I have it off?

[Robert]

Roger there are so many missing pieces to this puzzle that just to take the carbs back off you may find the culprit by accident. Did the bike run better or worse after you did the carbs. Can you accelerate to anything above idle? How do the plugs look? are you getting fuel to one bank of carbs, check by open the bowl drain and see if gas comes out. Is the linkage correctly hooked up and does it actually open the carbs? Do you have the air box off and is there a equal amount of air going into all cylinders.

[rogerthat]

The bike ran better at idle and at highway speed before but was horrible just off-idle.  Now it idles poorly, but pulls from a stop better but creeps back down to idle when I let off the throttle.  The plugs are white on #2, brown (normal) on 4 and 6, dark but not carboned on 1 and 3 and brown on #5.  At the exhaust I can tell that 5 is firing at idle as well as 2 and 4.  I checked and get fuel in all bowls.  The linkage is working with no binding (It snaps back to the idle-stop) and visual inspection of the butterfly position at idle-stop seems to be consistent after balancing.  After re-seating the intake runners from the carb box, I get suction on all six intakes (If I obstruct the flow on any of them, I get a brief rise in idle RPM followed by a drop).

[Mr. Nuts]

You may already know this, but as you said you were new here...you should be able to use the simplified method to get to the bowls which involves just lifting one bank of carbs at a time to drop the bottom of the bowls. Do a search on "slow jets" to see the easiest way to do this. Its not too bad of a job. You'll need a thin little ratcheting wrench and phillips attachment to get in the small access available as you tie up one bank of carbs at a time to drop the bowls. Replace slowjets with all new ones. While you are in there I suggest replacing the phillips screws on the bottom of the bowls with allen screws (available at the hardware store). You might also consider and inline filter in case you have any rust and gunk.

[Ricky-D]

It's the over-running that is the giveaway here.

When you return the throttle to idle, the motor should idle down fully completely and quickly.

If it were a single carburetor motor it would be a too rich idle mixture but since there are six carburetors, that would be a long shot that the problem is this particular thing. (richness)

You should re-examine your synchronization again.

Poorly synchronized carburetors will affect the motors idle in just the way you describe. Loafing cylinders will cause you to up the motor idle more than necessary and cause the overunning you describe.

Synchronizing should be performed at the correct idle rpm which is 800 to 1000 rpm's and constantly adjusted during the process to keep the rpm's at idle speed.

***

[rogerthat]

Since that's a heckuvalot easier than pulling the thing apart, I'll recheck the synch first.

Thanks

[Robert]

Roger do you still have all the smog stuff on? What bothers me is the slowly return to idle like Ricky said it either speaks of vacuum leak or synchronization, but sometimes if you have the carbon canister on the bike there may be a problem with the vacuum hoses that lead to that. I dont say that there isn't something wrong with the carb jets but usually they wont cause a slow idle drop.

[rogerthat]

Didn't de-smog it.  Put it back together like it was.  I was thinking about doing the WD-40 vacuum leak check in a few areas, but the first football game of the season was tonight.

Here's what I'll try:  First, recheck the synch.  Second check for vac leaks.  Third, pull and re-check slow idle jets.  After that, if nothing works, I'll be back begging for advice.

Thanks again everyone.

[Robert]

If you have whats illustrated in the diagram I would put removing all the desmog stuff at #3. 

[98valk]

Ah, for my knowledge, how would the petcock diaphragm cause the issue?

The intake Orings are brand new, and the rebuild included cleaning the entire carb assembly piece by piece.  I drained the tank during the rebuild and wonder if the slow jets could have become blocked again in such a short time?

Thanks for the input.

"The idle adjustment speed is inconsistent and the return to idle is really slow.  It seems to be running on three cylinders based on exhaust temps. "

slow return to idle indicates a lean condition.

usually this is idle mixture screws are not opened enough. can be petcock, diaphragm is leaking and not fully opening, thereby limted fuel flow, causing a lean condition. Or some other vacuum leak.
also check the tank vent line, could be pinched, thereby restricting fuel flow causing a lean condition.
Also be aware that front two carbs can run leaner due to thier fuel supply coming from the center carbs and not directly from the tank.

[rogerthat]

Ok, I'm bumping this thread:

This is for the people who wonder "what happened?" regarding tech questions and the outcome.  I had posted over a year ago regarding bad idle/off-idle performance and uneven firing at idle.  Here's the result:  I have the bike running well again and it took about six carb removals.  I had a house remodel in the interim and some medical issues, so my time couldn't be dedicated to the bike entirely - (I'm sure you'll understand.)  In the end, I replaced the slow jets with 38s, cleaned the tank with rust cleaner, and backed the jet screws out to two-and-a-half turns (the manual suggests 1-3/4 for '97s but the new slow-jets probably change that... ).  I balanced "on the bench" by measuring the butterfly gap in each barrel and reassembled.  That last combination of 2-1/2 turns out and the 38s got it running.  It now idles and  comes off-idle beautifully.  How I missed the power of the Valk.  The only advice I have for carb issues is:  Take 'em out and clean 'em.  I can now (Lord help me) get the whole bank of carbs out from the left side by only removing the left three intake runners.  Also pay attention to the o-rings in the pilot jets.  They crush easily.  Call it a success story and sorry the post is long.

Enjoy,
rogerthat

[Thunderbolt]

wondered how you came out.

[shortleg]

  Those carbs look good, but man can they be a pain.
 Always glad to hear about a good ending.
             Shortleg[Dave]