Idle still dying off

[Guest]

As I reported in this thread http://www.thegsresources.com/_forum...d.php?t=197508, I experienced the bike running well for 45 minutes then at stops the idle would sink under 1000 rpm and the bike would die.

After removing the carbs and cleaning them for the 4th time and then having to spend hours over the long weekend to even get it to run and idle, tonight it is doing exactly the same thing sitting on its center stand connected to the I/V bottle. It is now dying sooner, say after 3 or 4 minutes, the idle drops from around 1200 to just under 1000 and dies.

I have also noted two other things: 1) If I attempt to blip the throttle while its still hovering around 1000, it immediately dies. 2) if I try to dial in more idle using the idle knob no number of turns makes any difference, the revs don't go up and the downward drop in revs continues until it dies. Once restarted the revs jump to 6,7, or 8000 ( depending on how much I dialled in the knob) until the idle knob is backed off.

At this point I am thoroughly disheartened by my inability to get it running. What is worse is knowing that even if I do get it running properly I will not trust it and will then be forced to sell.

Any thoughts on these newly appearing symptoms?

Thanks,
spyug

[chef1366]

I had this problem when I had the wrong size pilot air jet installed or it was partially blocked.
Are your vent lines clear?

[BassCliff]

Hi,

This was the behavior exhibited by my bike after I performed a valve check and synchronized the carbs last weekend. After putting the tank back on I started it up to adjust the idle. It would start immediately with the choke but would die if I turned off the choke. It would not idle at 1100 rpm in a stable manner. I had to crank the idle screw in a LOT to get it to idle somewhat steadily at 1500 rpm. I was adjusting the throttle cable, the idle knob, grabbing the throttle every time it wanted to die, going back and forth. I messed with it for more than a half hour until it was supper time. So I took a break.

I finally realized that I had forgotten to put the vacuum port screws back in the intake boots.

Essentially, I has a massive air leak in my intake system. After I realized my mistake it took me 5 minutes to adjust the idle perfectly.

I'm sorry, I haven't read your other thread. But your situation reminds me of mine last weekend. Are you sure you don't have a big air leak somewhere? Are all the carb jets snugged? Are the rubber plugs in place?


Thank you for your indulgence,

BassCliff

[Steve]

At this point I am thoroughly disheartened by my inability to get it running. What is worse is knowing that even if I do get it running properly I will not trust it and will then be forced to sell.

Have you started thinking of the "creative" wording for the ad yet?

Maybe argonsagas can help with that. With his ability to twist a phrase, it should sell in no time, and the buyer will thank you for overcharging him.

.

[Buffalo Bill]

Not enough info…

All I hear is, you're working the carbs, over and over.

What about valve specs, and compression readings?

Ignition power?

Vacuum readings?

Intake pipes and O rings, have you replaced those yet?

[spyug]

Ok to recap
a)Carbs are stock and now are clean as a whistle & with fresh o-rings
b)the vacuum port screws were put back in after synching
c) Morgan carbtune shows carbs are balanced and draw lots of vacuum at idle and under throttle ( will pull the rods right to the top)
d)valves were set to spec about a month back
e) compression is unchecked but must be enough to run and as it pulled like a freight train when ridden for 45 minutes last week
f)Intake pipes are in good shape, supple with no cracks or splits
g) I do not have fresh o-rings for the boots (on order) but a spray test doesn't show any leaks

To me it must be carb related especially with these symptoms:

I have also noted two other things: 1) If I attempt to blip the throttle while its still hovering around 1000, it immediately dies. 2) if I try to dial in more idle using the idle knob no number of turns makes any difference, the revs don't go up and the downward drop in revs continues until it dies. Once restarted the revs jump to 6,7, or 8000 ( depending on how much I dialled in the knob) until the idle knob is backed off.

I'm especially confused by the lack of response to idle knob adjustment since when it is dying off and I dial in the knob a good 8 or 10 turns there is no reaction. In my experience, on any other bike I've worked on in running condition, even a small increase in idle screw corresponds in an increase in revs.

At this point I'm getting out of ideas and I'm thinking that I need to clean and rebuild my spare set and see where that takes me.

Thanks for the input folks.
Spyug

[Nessism]

g) I do not have fresh o-rings for the boots (on order) but a spray test doesn't show any leaks

Spray test is unreliable.

My suggestion is same as your last thread, replace the O-rings. They may not be the cause of the problem, but they are the obvious place to start.

[JEEPRUSTY]

All I hear is, you're working the carbs, over and over.

What about valve specs, and compression readings?

Ignition power?

Vacuum readings?

Intake pipes and O rings, have you replaced those yet?

LOW compression maybe
valves off or something else


last year ahead of my dead head I had some weird carbby like issues when in fact the top end had burnt valves.

[nejeff]

I'm especially confused by the lack of response to idle knob adjustment since when it is dying off and I dial in the knob a good 8 or 10 turns there is no reaction. In my experience, on any other bike I've worked on in running condition, even a small increase in idle screw corresponds in an increase in revs.

At this point I'm getting out of ideas and I'm thinking that I need to clean and rebuild my spare set and see where that takes me.

Thanks for the input folks.
Spyug

I've had my 80' 550E for a little over a year now. Almost everything your describing sounds like my own battles. Only difference is I did replace the carb boots & boot o-rings. After my third teardown it still does not hold idle well under 1500 rpms, I use constant blipping at the start. Idle falls out and the big knob doesn't stop it but once it warms up the idle is very high and then back to turning the knob back down. I'm feeling your pain and watching your thread. Good thing my 850G is running well...good luck.

[mpencegs]

Would a decrease in power from faulty charging system lead to this? Have you pulled the plugs to get readings and tested the stator and r/r?

[hjfisk]

Would a decrease in power from faulty charging system lead to this? Have you pulled the plugs to get readings and tested the stator and r/r?

This was what I was thinking, voltage a t the coils or are the coils possibly heating up?

[Buffalo Bill]

Well, if the problem is crud in the passageways, be sure to get a magnifier, and have a good look down those holes.
I was plenty frustrated with a 550 Seca, and I had dipped and cleaned those carbs a few times.
With a magnifier, I saw a thin coating of crud lining the main jets.
Just scraping that tiny layer of crud off, sure made a difference.

[spyug]

Thanks folks, I am trying to digest everything.

I have had previous experiences with failing coils and while this is similar its not much like what I've experienced in the past. On that bike, a Virago 500 V-twin, it would run fine for 20 minutes then start to miss fire, one cylinder would quit, it would limp along for a minute or two then die. This is just a gradual but abrupt decrease from an idle of around 1200 to under 1000 then die.

As far as a burnt valve or air leak at the intake boots or o-rings , I'm doubtful as I would think that would make starting super hard and it would run like crap from the get go. when I had it running fine and out and about last week it started easily even without choke and ran like a freight train in all gears. No hesitation or stumble. Bags of power and acceleration.

What really draws me back to the carbs over and over is the symptom of not responding to substantial increases in the amount of idle knob adjustment.8 or 10 or more turns of an increase make absolutely no change in revs. That is unheard of in my experience. Couple that with instant death with an attempted blip of the throttle and it just has to be carb related would you not think?

At this point, I'm going to resurrect my spare set of carbs and give them a try. I will change the o-rings on the intakes when I can, as well.

I'll let you know what happens next.

Thanks again for all the interest and suport, it all that keeps me going right now.
Cheers,
spyug

[GateKeeper]

Hey spyug,,,,I have 2 weeks of vacation coming up.....I can give you a hand....well at least come over and drink beer and supervise..... :-)

I will be legal to ride by Friday......Insurance I get tomorrow, and sticker for the plate on Friday.....

good times are ahead...

[bwringer]

What do the plugs look like?

Where and in what state is the air filter?