Topic: Hanging Idle: little help pod issue?

[Nortstudio]

This is where it gets a little hinky...

I got a set of replacement carbs (which it now seems may have been a mistake) to do a total rebuild on. I cleaned all the parts - including the needles and seats, but when I installed these back into the carbs, the needles seemed a little too "stiff.". By this I mean, the olds carb needles allowed the weight of the float to depress it slightly, whereas these on the new carbs didn't. They had planet of spring, but held firm against the weight.

So I swapped the needles, and the seats too, replacing them from the old carbs. But at that point (this was on the 19th cleaning/off the bike!), I had mixed up which needle went to which seat. I should have kept them by the carb numbers.

Is there an obvious way to tell which seat right?  Will the level be different etc?

I'll check the pin to see if it's binding. Off they come again

[TwoTired]

The float needles "marry" to the seats.  Doesn't take long for new bits to polish each other for perfect seal.  Swapping around parts defeat that and they have to polish each other via vibration to seat well.  Sometimes used mismatched ones never fully seat entirely.
You can coat the cone tips with black marker and insert them into the seats give them a little twist and then closely examine both cone and seat for even transfer of markings, or wear off.

You can also polish them to each other with some rubbing compound between seat and cone tip, and then rubbing them together a few turns.
Be sure to clean off the compound after wards.  The tiny grit really shouldn't be fed to running engines.

It sounds like your spring pins aren't really clean inside them where the spring and plunger lives.

If the seats and cones aren't well matched, then running vibration can make fuel levels variable until the cone routinely seals in the float valve seat.

Cheers,

[Nortstudio]

Thanks so much TT.  I'm afraid I wasn't thinking this far ahead in my desperation to get the damn things back together and running correctly.  I was pretty good the first few times, with separate containers for each carb etc.  But at a certain point I was storing parts in my ears for easy access I was ready to be done!  Foolish...

I will certainly give the rouge a shot.  I have black, red, brown(?) and white.  Any thoughts on which one would be best?  I will make sure it's all clean after.  Otherwise it's trying each needle with each seat, until it works well.... I would do the possible combo math, but my head hurts already from huffing all this gas! 

Appreciate the help.  I'm sure i'll get it.  Was just hoping to not have to take the darn things off again.  I'd say I was being lazy, but I'm about to hit double digits on this rebuild....

[Nortstudio]

Since I am going to be diving into these carbs again today - I would like to address the fact that the slides do not seem to snap back as fast as they should.  I have 2 springs (one from a rack of 022a, and one from my old carbs- 087a).  They look totally different.  The one on now is a hair longer, but all spring.  The one from my old carb is given it's total length by the piece that wraps around the "stay" which extends out from the spring area.  I will try to take a photo. 

The problem is: when I tried the old spring (weird extension one), it didn't snap the throttle butterfly back at all.  Weird, because it seemed to work fine on my old carbs.  So I went with the one from the 022a.  But I'm not sure that is where my issue is coming from.  The 022a one also has a small rubber sheath around it, and I'm not sure if that causes any issue either.

It almost seems as if the slides need a little bit of lube to make them snap back a little quicker.  It's just a hair slow.

[TwoTired]

The stock spring had a rubber tube around it.  Vibration damper, I think.

Slides can gum up in the bores.  Other damage can occur too, which makes them drag in the carb body.

Disconnect the throttle cables to isolate carb issues or cable issues regarding slide return.

Cheers,

[Nortstudio]

The one on there now has the rubber. I'll leave this one for now. The float needle seems to have "fixed" itself, and has worked properly in 3 tests of empty then fill, empty then fill. I'm going to move on for now.

I was hoping the slides/bores were not gummed up, because the entire carb rack was apart to pieces, and I made sure to clean them. But then again, that dent work so well withthe slow jet....

Great call on isolating the cables to determine cause and effect. I recall the butterfly snapping back pretty violently when off the bike. Maybe this is merely a cable snafu.

What's the consensus on using cable lube on these motion pro cables?  I've heard mixed things. I have the special lube and apparatus for it - but have refrained due to conflicting tales.

Thanks again guys.

[Rookster]

I'm not sure this applies to the 550 but I had a similar problem with my carbs (CB750K) not returning all the way and hanging the idle.  There were a few issues that contributed to it.  One was the linkage that lifts the slides was not spaced perfectly to the carb bodies which created some drag.  When the bike was not running there was a nice hard snap when I turned and let go of the throttle but when the bike was running the idle would hang at about 4k.  I loosened the linkages and the pins and had to re-adjust them to ensure there was no drag between the slides and carb bodies.  On the 750 the linkages are adjustable and if someone loosened any of the adjustment screws at any time I bet there is some slight mis-alignment.  The other problem I had was an air leak.  The wd-40 method for finding air leaks is really not a great test.  You may have to do it a bunch of times before you find the air leak.
Scott

[Nortstudio]

I'm not sure if the linkage is the same on the two bikes. There are parts on the 550 that go up and down - with brass caps on them. They attach with a ball joint. not sure how I would adjust those.

At this point, im not getting the hanging idle any longer. Just a breath of time between letting go of throttle and gas being stopped. Not sure how else to describe it.

Is there a better method for finding air leaks than the WD-40 one?  I think now that the hang is gone, I may be ok. But I'd love to check it if there is a better way.

Thanks,

Scott

[Rookster]

On the 750 the linkages are able to slide along the shaft by loosening the screws/bolts that hold them down.  The shafts are also movable.



There really isn't a better way to check for air leaks that I know of but if the leak is slight it may take a few tries with the wd40 to get the motor to rev higher.

Scott

[TwoTired]

What's the consensus on using cable lube on these motion pro cables?  I've heard mixed things. I have the special lube and apparatus for it - but have refrained due to conflicting tales.

The folklore is that Honda cables have a teflon lining, that is damaged by constant bath in oil/petroleum products
I don't know what the motion pro cables have for a lining.  It is conceivable that to save manufacturing costs, they would not use more expensive teflon, which would allow a lower sales cost and/or higher profit margins.

Popular/cheaper is not always better for the consumer.  And, simple "consensus" does not always yield the best choice.

Anyway, I have used a product called Dri-Slide on both Honda and other brand cables.  It goes in wet, but the liquid carrier evaporates, leaving moly and graphite inside the cable's wearing areas, and it won't attract or trap abrasive dust and dirt as oil based products can.  I don't believe it damages the teflon linings of Honda cables either, since the solvent carrier evaporates pretty quickly.

FWIW.
Cheers,

[Nortstudio]

This is what the 550 mechanism looks like.



I'm really not sure what all could be causing hang up other than the part that goes through to top of the carb - perpendicular to the shot above. Unless the little rubber piece between the brass caps is binding.

Going to try TTs suggestion of separating the cables from the carb to see what's up in there.

That product for lube seems good TT. I just have normal oil based spray. I've used it for the old '62 vespa with good results. Not sure if these cables would suffer. I'll put stock cables on my list....

[MoMo]

+1 on TwoTired's recommendation of Dri-Slide-have used it since day 1(way too long ago )...Larry

[Nortstudio]

Which dri-slide do you guys get?  I see Bike Aid and a "motorcycle Lube"

[MoMo]

Pretty sure Bike Aid is the same product...Larry

[dave500]

the last clutch cable i got was a genuine honda one sealed in a bag with no teflon or anything on the wire inside?

[TwoTired]

the last clutch cable i got was a genuine honda one sealed in a bag with no teflon or anything on the wire inside?

The teflon jacket was part of the inner sleeve.  I don't think you can see it without dissecting the cable jacket or otherwise dismantling the cable assembly.  The ends of the jacket are capped on all the ones I've seen, blocking direct view.

It could be the clutch cables are constructed differently than the throttle cable, I suppose.

It's also possible that Honda changed suppliers, and neither the current crop of engineers or the buyers are bothering to evaluate the latest vendor offerings.

Honda may have yielded to the same cost rather than cost-for-quality mentality that most consumers prefer these days.

Cheers,

[dave500]

the old one was genuine and the coating was visible,none on the new one.

[Scott S]

 I agree with TwoTired....I replaced the throttle AND clutch cables with genuine Honda. Made all the difference in the world. Expensive, but I also bought two cheap cables that were crap. The aftermarket throttle cable was too long...I ran out of adjustment....and the clutch cable was stiff and hard to pull. No contest vs. the real deal.

[Nortstudio]

Stock cables, as well as dri-slide, going in my list for next purchase. I finally got the hang straightened out with a new pull cable. It's tough to pull now (I will be developing popeye forearms in a week, but it snaps back now like a bi#€h! 

I've read about a ton of causes for this stiff pull, but with te lower drag bars, the run is best I can get right now. At least I'm not accelerating heading into traffic now!

Thanks for all the help folks!

Scott

[Nortstudio]

As usual, I spoke too soon. I need to be a little guarded in my optimism with these carbs.

I am now having the float issue again (I assume) which is now happening only on carb #4. I just want to confirm I'm not crazy here - before I start trying to get mismatched needles paired with seats.

The gas flows out of the overflow tube ONLY when I turn OFF the gas. If it's sitting, running or not running, with petcock on, no leaks. It's only when I turn the petcock off.

Is this still my float needle not working correctly?  I thought it would pour gas while petcock was ON?

AND.... it is now hanging up again. New cables, seems to help for a second. Now that the engine is warm again, it's hanging just like it did. Would this indicate that once gas gets in there, the slides are getting sticky???

[KingCustomCycles.com]

petcock on = gas flowing.  Are you sure you are not selecting reserve with a less than full tank? gas is a lubricant and has a "lubricity" rating.  And I know this how?  :-)

[Nortstudio]

I am definitely choosing the off position.  When I cleaned the tank, I check=ed to see that it functioned properly with the hoses off.

[KingCustomCycles.com]

Fuel should not flow in the off position.

[Nortstudio]

It doesn't flow fresh gas - it releases the float amount, it seems to me.

[KingCustomCycles.com]

That is a bad needle seal, float hanging up, cracked copper tube.  That is all the possibilities I have ever encountered.