Author Topic: Hanging Idle: little help pod issue? (Read 9870 times)

Nortstudio · « **on:** July 22, 2011, 12:44:44 PM »

1976 CB550K with freshly rebuilt 087a carbs and cleaned tank.

****PREFACE: I AM ASKING THIS TO SEE IF THERE IS ANYTHING MORE I CAN DO WHILE I WAIT FOR MY REPLACEMENT STOCK AIRBOX CARB BOOTS... I PUT EMGO PODS ON TO KEEP INTAKE CLEAN WHILE I WAIT.****

I recently rebuilt a set of carbs for my bike, a complete tear down, all 4 off the rack/plate. Cleaned, blown etc. New rebuilt kits. Fixed the one carb that still had slow jet plugged yesterday (thanks Duanob and others!), and all 4 cylinders are firing well.

I did a carb sync today, got all 4 carbs tuned nice and even. Unfortunately, the idle is still hanging when I reset the idle after sync. I can blip the throttle several times without hang, but then it will hang on the next blip. Or sometimes, it seems like it wants to take off on it's own. I visually saw all carb slides return/lower in unison when it was off the bike.

My questions are:

1. Does this seem like it's related to the fact that I have less restriction from pods (and stock jets)? I'm not looking to make the pods work, I will wait for the boots if this hang is caused by the less restriction, but I'd love to trouble shoot while I wait, if there are steps I can take to fix this idle now.

2. I put new gaskets/o-rings in the manifolds. It was suggested to me long ago, and this was the first time I had the chance. When I removed the old ones, they were flat (like the gas cap gasket) and the new ones were perfectly round (like a jet o-ring). Is this normal? Were the old ones made flat from pressure, or did I get the wrong ones? Hence, causing air leaks. I tested this area with WD-40, and got no increase in RPM.

3. Could hanging idle be from the mystery oil I put in the tank to prevent flash rust? I initially put about 1 gallon of fresh gas in the tank, burned it off, and then filled it near full yesterday. I figured it would be gone by now. I did put a little Seafoam in there yesterday, but I have used this in the past without hanging idle.

Thanks in advance,

Scott

Bankerdanny · « **Reply #1 on:** July 22, 2011, 12:52:29 PM »

Did you make any changes to your throttle return spring?

Nortstudio · « **Reply #2 on:** July 22, 2011, 12:55:19 PM »

The spring was missing from the newer rack of carbs, so I took one from a spare rack. I put it on, and although it doesn't seem to snap back as much as some that I've seem, it does in fact go back to the lowered position.

I could maybe swap it for the one that used to be on my bike (3rd set of carbs) if that would be a good diagnosis. It's pretty rusty, but my old setup didn't hang.

Bankerdanny · « **Reply #3 on:** July 22, 2011, 12:58:34 PM »

I would try that. Maybe the slides are wandering up a bit from engine vibrations and a weak return spring.

I know you cleaned the carbs, but if it persists you might take a look at your needles. I had all kinds of fast idle issues with my FJ (albeit with CV carbs) because the needles had a little ridge of gunk that was keeping them from sealing properly.

TwoTired · « **Reply #4 on:** July 22, 2011, 01:00:34 PM »

Did you try to turn the air bleed screws inward for the stock position?

Nortstudio · « **Reply #5 on:** July 22, 2011, 01:02:41 PM »

Thanks Danny. Duanob mentioned something similar, but i had cleaned them, and thought they were fine. But then again, I thought #4 slow jet was clean too - and it was jammed.

I put tried the air bleed screws at stock 1.5 turns out. Also tried it at 1, and at .5 No luck. But honestly, I didn't spend a ton of time with them in each position. Just enough to blip a few times, because the 104 degree heat started cooking my brain

Any thoughts on the intake gaskets?

Thanks

Bankerdanny · « **Reply #6 on:** July 22, 2011, 01:05:03 PM »

Intake gasket leaks are pretty easy to diagnose. Get the bike idling and spray WD40 around the boots. If the iddle drops then you know that you have a leak.

MoMo · « **Reply #7 on:** July 22, 2011, 01:08:08 PM »

The rubber would be flattened over time so it would appear flat but would have been round to begin with. I agree with the heat-was out in the shop for an hour then said what am I doing and came inside. Try adjusting the air screws be ear but I think your problem will be solved with an air box. I have a 400four with pods and just spent $40 for an air box...Larry

Nortstudio · « **Reply #8 on:** July 22, 2011, 01:16:16 PM »

Danny: I tried the WD-40 trick, no change in RPM.

I have never had any luck with the "ear-tuning" with the air screws. i think that may be because of the type of air screw this carb has. It's somewhat unique I think, and has less effect, like some of the other carbs.

Believe me, I have had an air box since I got the bike and will be sticking with it, but when I removed the carbs this time, 3 of 4 boots had rips, 2 of them were terminal. So I got some "almost new" ones from a forum member here - and they are on their way. Just want to make sure there is nothing more I can do for this think while i wait. After a complete rebuild, waiting on the air boots is a little anti-climactic

I will try swapping the spring to see if that helps some.

vance · « **Reply #9 on:** July 22, 2011, 01:59:05 PM »

check your spark advancer. the weights need to move freely and the springs need to be tight enough to return the weights to the center.

Nortstudio · « **Reply #10 on:** July 22, 2011, 02:01:49 PM »

I checked this last fall, and everything seemed good at that point. I will check again. Is there anything obvious to look for? Something that would go bad in that period of time?

I guess that means doing the timing again??? Oh joy

TwoTired · « **Reply #11 on:** July 22, 2011, 02:04:11 PM »

How much free play do you have at the twist grip before the slides move?

Nortstudio · « **Reply #12 on:** July 22, 2011, 02:11:11 PM »

Hard to say without being there right now - but I would say less than 5mm before the throttle cable begins it's work.

Sorry, I know that's not a very good answer. I adjusted it pretty tight the first time around. Should I try some more free plat. I know the manual says 10-15%, or something like that, but I don't think it's that much.

TwoTired · « **Reply #13 on:** July 22, 2011, 02:18:57 PM »

It is important that there is no tension on the either cable when the grip is released. You should be taking up a little bit of slack upon actuation. If the cables are in any way fighting each other, friction will interfere with free movement.

They are quick the adjust. Add some slack to see if there is any relation throttle sticking.

Could you have air induction leaks? Did you vacuum sync the carbs with the pods installed? Does the sync change with the pods removed?

Cheers,

Nortstudio · « **Reply #14 on:** July 22, 2011, 02:25:21 PM »

I will check for the throttle cables fighting each other. Thanks TT. I had not thought about that.

I checked for leaks, and at least with WD-40, it seemed to be air tight.

I DID sync with the pods, but did not take them off to see if that would change anything. I figured they were acting almost as nothing at all to begin with, so I never thought to take them off to see differences. Should I remove them and just see how it blips, and whether it helps the hang? Or are you saying to do the whole vacuum sync again without them?

Appreciate all your help folks.

MoMo · « **Reply #15 on:** July 22, 2011, 02:31:12 PM »

Quote from: Nortstudio on July 22, 2011, 02:01:49 PM

I checked this last fall, and everything seemed good at that point. I will check again. Is there anything obvious to look for? Something that would go bad in that period of time?

I guess that means doing the timing again??? Oh joy

Use the timing light to observe how the advance unit is working. If it is hanging up you will see it on the alternator. How many miles have you put on since last done in the fall? ...Larry

TwoTired · « **Reply #16 on:** July 22, 2011, 02:34:22 PM »

It's just a test.
Consider if one pod somehow provided more pressure drop than the others. This would show up as a vacuum difference on the gauges. Balancing with this bias would actually de-sync the carbs.
Anyway checking for a sync change, pods on pods off, might tell you something...or not.
Just a thought.

Have you checked actual fuel level in the carbs? Sorry if you already answered that question.

Cheers,

Nortstudio · « **Reply #17 on:** July 22, 2011, 02:40:58 PM »

A clear tube gadget to make checking float fuel level easy just arrived in the mail. I'm going to check in the morning. I might try another sync if all of these other things fail. By that time, the boots might be in. They can get here soon enough!

Photolar, what would I see on the alternator? Sorry, don't understand that test??? I have about 1500 miles since last 3000 mile tune up. I guess that makes mine a 1500 mile tuneup

DJ_AX · « **Reply #18 on:** July 22, 2011, 03:14:37 PM »

Had a very similar issue.
It turned out to be a slight bend in the push cable from installing it...
Sometimes that bend would hang up instead of sliding into the cable sleeve.

MoMo · « **Reply #19 on:** July 22, 2011, 03:20:49 PM »

The timing light will flash at the f mark and move between the advance lines as you rev the motor, when you let the throttle go you should see the light flash smoothly back to the f mark, at least in theory. Worked for me on the last bike I had with a stickly advance. I could see the hang up. The timing light will also tell you if you need to reset the timing-I doubt you need to though. Flash at the f and fall between the advance lines for both sets of points and you're fine...Larry

Duanob · « **Reply #20 on:** July 22, 2011, 03:24:24 PM »

I wouldn't put a lot of thought and energy into this until you get your intake completed. As Photolar said that might fix you right up. You could be beating your head against the wall for nothing.

Checking the floats with the new tool is a good thing to do, not only the level (1 or 2 mm below the lip of the bowl) but time how long it takes to fill and shut off. They should fill pretty quickly and all 4 should take about the same amount of time. if you have a slow one or two there might be a plug somewhere that needs to be cleared out.

Stay Cool

Nortstudio · « **Reply #21 on:** July 22, 2011, 03:28:57 PM »

Thanks folks. Photolar, thanks form the clarification. I will try to throw the light on it to see if I notice anything.

Tomorrow, I plan on completely checking the throttle cables. Hopefully it's something that simple.

If that doesn't do it, I will see if swapping the spring helps.

If that doesn't do it, I will check the fuel level in the floats.

Then....If weather permits (meaning, I don't melt), I will try a resync without the pods on to see if these things skewed the results.

Otherwise, it's waiting for the new boots to get more into than this. My reasoning for wanting to check these things is that I'd like to get back to riding,once they arrive, as quickly as possible. So if there was anything I could deal with, to check it off the list, better to do it now.

I will stop banging my head against the wall as soon as I check off the things on the list above.

Thanks again everyone, for all your time.

Nortstudio · « **Reply #22 on:** July 23, 2011, 10:38:59 AM »

So, I hit the garage today with gusto and energy (early AM, before the heat hit!).

First thing, loosened the throttle cables, and immediately, the snap back to closed position was improved. Thanks TT!

Since this seemed pretty good, I decided to keep the current spring in place, because it's not rusty like the other one I have. I will keep this in mind, if all else fails...but moving on.

I turned the gas on, after it sat for a second, saw leaking from the overflow tube #2. Took the carbs off and checked the innards. The float needle seat seemed a bit clogged. I blew it out, rechecked the float height, adjusted a little, and put the carbs back on the bike. Left the pods off the bike.

Fired it up. At first, it seemed to not hang. There was no gas leaking anymore, but eventually, it began to hang again. Also, at this point, I started getting backfiring from the left muffler (I have 4-2). There seemed to be some smoke coming out of the mufflers too (yesterday also). Tried to smell it, smelled a little like gas, but not totally sure. Pretty sure it was exhaust and not vapor, because it made my eyes water. Not sure if this could be from the tank cleaning I did before the rebuild. I got all the water I could out with denatured alcohol, and blew it best I could with compressor.

Heat got to me....so I headed home, figuring I should wait for the air box boots. Got home, and they are here! Now I am wondering if I should brave the heat and head back later, to throw them on and see what's what.

My only concern is whether I should be checking some other things, before the boots/air box are back on, because it's so easy to remove the carbs without them there. I am thinking that maybe I should do one more FULL clean to make sure I didn't miss anything else, even though it seems that i have NOW got it all straight.

Any suggestions welcome....

Scott S · « **Reply #23 on:** July 23, 2011, 11:06:01 AM »

Quote from: Nortstudio on July 22, 2011, 12:44:44 PM

I recently rebuilt a set of carbs for my bike, a complete tear down, all 4 off the rack/plate. New rebuilt kits.

This may be your problem right here. I was fighting a similar problem with my CB500 and was about ready to tear my hair out. I THOUGHT I had stock jets in it until I found a bank of parts carbs and noticed that the slow jets were different.
The jet on the left is a genuine Keihin part. The other two are aftermarket. Nearly everything about them is different: length, orifice size, count and location, etc. I swapped the stock jet in and all my issues went away. Do you have the stock Keihin jets for your carbs?

Nortstudio · « **Reply #24 on:** July 23, 2011, 11:18:01 AM »

I'm not sure. This rack is all new to me, and I didn't look at them next to my old jets. I'll do that too, when I open them up...again!

I might grab some of the jets from my old carbs, which were working decent, and swap them for the ones that came with this new rack.

Got the boots, so hopefully that will get me on my way.

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Author Topic: Hanging Idle: little help pod issue? (Read 9870 times)