Cold Exhaust on Right side

[almaoliphant]

Hey all.  I jumped on my '97 Standard Valkyrie for my morning commute, and it was running sluggish.  The engine wasn't pulling, and the right side header pipes started to blue quickly... (ya, there go my new Jardine's)  I also saw a good amount of fuel pouring over the top of the engine.

I was pretty sure the o-rings in the carbs had not been changed since the factory.  So with the sluggish behavior and the waterfall fuel, I thought "hey, the engine isn't getting fuel, so it needs a carb job."

Yes, the o-rings needed to be changed.  Many of them, especially the fuel rail, were cracked and falling apart.  I just finished wrestling with the carbs, and started the bike again.  No fuel waterfall, thankfully.

But, the same sluggish running engine problem.

I gapped and installed new plugs.  No change.

I did notice that at idle, the exhaust out the right side is cold.  (The left side is hot.)  But, when I increase the revs to 2500, the right side starts to get hot, and backfires when I left off the throttle.  So I'm thinking there's excess resistance in the wires or plug?

If I pull a plug, ground it, and watch the spark, the spark seems weak on the right side cylinders, but not overly weak.  I've seen worse.

Here's my confusion:

1.  the coils run two cylinders each: 1-2, 3-4, 5-6.  But, only the right side exhaust (cylinders 1, 3, 5) is cold at idle.  If a coil was bad, wouldn't at least one cylinder go down on each side?  Not all the cylinders on one side.

2.  the plugs are new, so we can rule them out.  Right?

3.  the carb "should" be running right... assuming I'm not inept.  (This could be argued.)

What am I missing?  Can the wires go bad, but only on one side?  Any thoughts, ideas?

Thanks in advance.
Alma

[sugerbear]

i'd check the fuel lines. i think the line is divided at a tee and then goes to each side.
maybe the one side is a little clogged.

just guessin.

[3W-lonerider]

my conclusion..plugged up slow jets in the right side carbs..

[John U.]

+1 on 3W-lonerider's diagnosis. The proof is that the right side cyclinders begin to fire at 2500 rpm. At higher rpm and/or more throttle the main jets will pass enough fuel to ignite. If you use the choke/enricher you will find the same thing happens. You may get by with a heavy dose of Techron, othewise it's slow jet cleaning or replacing time.

[almaoliphant]

Thanks for your comments. 

sugerbear:

I replaced the fuel lines at the same time as the o-rings in the carbs.  I don't think they're plugged, but I could be wrong.

3W-lonerider & John U:

Humm...  I'm thinking outloud, er, onscreen.

The previous day's ride (before the sluggish day) was great.  So this "all of the sudden" poor performance suggests an electrical problem to me... but if I was right, I'd be riding, and not typing.

Could some of the rubber from the old o-rings brake loose and plug the slow jet tubes somewhere upstream of the actual brass slow jet?  The fish-net filter screens that stick out into the fuel rail tube, separating the carb from the fuel rail, seemed to be clean.  (It was difficult to see into those small holes.)  Any pieces of rubber would have to be very small to pass through the screen, and thus should have been stuck in the jets themselves, right?

I was meticulous, cleaning all the jets the first go-around, so I don't think the slow jets are plugged.

Maybe the holes are too big?  Can the jets simply "wear out?"  But, if they are worn out, shouldn't the engine performance degraded over time, and not overnight?

I suppose I could go back to the jets, and replace them.  I could order a jet kit, but I like the one I've got (well, the way they used to perform), and the $100 in my pocket. 

[Scott from FL, now in Maine]

Okay this may sound foolish, but I say it having made a fool of myself this way. My bike ran great one day, the next day I started it and it sounded wrong, stuttering a bit. I applied choke thinking at the time it wasn't cold out so I should not need the choke. I shut it down, checked fuel lines, opened right bowl and got slow drain of fuel. Thought ignition problem, checked all connections at the coils. Tried again same problem right side not running at all! By this time I was running on 3 cylinders only! I reved it just like you did and the pipes on right started to warm and cylinders started to fire, but back at idle I was back to 3 cylinders. I was going nuts! Then I sat on the bike tried again to fire it up and it smoothed out and ran fine!!! The problem was completely fixed when I turn the tank to reserve fuel!!! The whole problem was gas!!! The tank was to low on fuel! Sitting on the stand tilted the bike enough that the right side was loosing fuel but not the left!! I felt like an idiot and had wasted a good part of the afternoon!

I say all this to ask. Do you have enough fuel in the tank?? 

[almaoliphant]

Scott in FL:

Now that's funny! 

I will check the tank.  I think I sat on the bike, upright, during some of my "revving," but I admit, I didn't pay attention.  You've given me something that makes sense to check. 

I'm not sure I could admit that your fix worked, though.  If you see me make up some ghost story about the brake cable being mysteriously hooked through the electrical system, you'll know that's code for "thanks, I just didn't have enough fuel in the tank."

[Patrick]

Do you a good fuel supply to those cylinders?? Open the drains and check.. If the supply is good, my money is on plugged slow jets..

[fstsix]

Looks like the Shutoff valve Diaphragm split. it will starve your motor and puke through the vacuum line into some of the cylinders. 1997? some would say these will last 150.000 miles but it is the age of the rubber not the millage the that causes failure. put a vacuum pump test on that line on your petcock see if it holds.

[Ricky-D]

If you do the math you will see the motor only needs a very small amount of gasoline for idling and revving.  Riding at normal traffic speeds the motor is consuming gasoline at the rate of a couple of ounces every two minutes.

If you would measure the amount of gasoline coming from any float bowl drain you will find this surely exceeds the baseline of an ounce a minute.

It is not logical to assume that all three carburetors on the right side would crud up at the same time.

Your problem is most likely a low volume of gas in the tank that has already been mentioned, exacerbated by leaving the bike on the side stand while performing your diagnosis routine.

Back to the drawing board!

***

[98valk]

intake manifold O-rings, replace them. Also check your idle mixture screws, start at 2 1/2 turns out and tune from there.