Topic: 1977 CB550K timing/carb setup question

[Nick B]

if i lift the idle up more, you hear just tryin got suck in air and still dies.  when i cleaned them i could see throught them.  i did not want to go more because of possibly enlarging the hole.

[Master Ted]

What process did you go through in painting your wheels?

[Nick B]

ripped them apart

sent spokes out for re-chrome

powder coated rims  (stonger then paint)

[Master Ted]

powder coated rims 

Did you scuff, sandblast or de-chrome prior to PC?

[Nick B]

i now somebody and they chemically stripped everything for me.

[crazypj]

If you get a short piece of wiring harness and strip off the insulation a couple of strands of copper wire will polish out the jet without any risk of enlarging it. You took out the mixture screw, not the pilot jet which is as described, the one in front of your new main jet and emulsion tube/needle jet.
It looks blocked in the picture but I'm not making any sweeping statements at present after the starter clutch mistake. (sorry Raul )
PJ

[TwoTired]

Take a look at reply #8 in the carb FAQ.  There is a chart of the stock settings for the PD46A carbs.  Noteably, the needle clip was third from the top in stock configuration.

However, with pods and non-stock exhaust you have to re-engineer nearly all the jetting parameters for a street bike, including the slow jet size, main jet size, main needle position, main needle size, main needle taper, and possibly even the throttle valve cutaway.

Hope you have a test track or a Dynomometer.  Or, you're in for a very long trail and error period 'til the carbs approach the streetabilty of the stock configuration.

Good luck!  You'll learn a LOT in the process.

[csendker]

**clunk**
**clunk**
**clunk**

That would be the sound of my head banging on the table as I realize the clip position that I searched so hard for was always right there in front of my face.  I did see that, but I thought it meant that my needle had 4 clip grooves, not set on the fourth groove (022A specs: "4 grooves" vs. PD46A specs: "3rd groove").  Which leads to the next question, 4th from the top or 4th from the bottom?  BTW, I've never had the carbs on my 550 apart and my spare 'learning' set has all 4 slides seemingly permanently stuck in place, so I've never had the needle out on a 550 carb.  I assumed the CB175 carbs that I've opened & cleaned had different needles.

Oh yes, and it's nice to hear from you again TT.

[mrbreeze]

Good to see you back Lloyd!!!

[Nick B]

I printed that chart poster size 2 weeks ago.  I'm the last one on that chart.  all the number correspond to it.  90 main jets, 42 slow jet, 2nd clip for needle (took out my old ones and that what they were set at) and float height.  i took my carbs apart again and have the slow jets sitting in carb fluid and giving them one more good cleaning.  the bike did run 90% better since the first cleaning but of course it does not run with out the choke fully.  will see what happens.

[bwaller]

Same here Lloyd, hope all is well in your world.

[Nick B]

Where could i get bigger slow jets?  or is that not possible?

[TwoTired]

Which leads to the next question, 4th from the top or 4th from the bottom? 

The pointy end is the bottom.  Start counting grooves from the top.

BTW, I've never had the carbs on my 550 apart and my spare 'learning' set has all 4 slides seemingly permanently stuck in place, so I've never had the needle out on a 550 carb. 

Well, it's time you did!
Unless the slides are corroded to the slide bores, they can be freed with a good slathering of WD-40, PB Blaster, or other light penetrating fluid at any and all interfaces between slide and carb body.  Then "worry" the throttle rocker back and forth until movement is achieved.  Best done with throttle cables and twist grip attached, as that is less likely to break off bits of linkage in the carb bank while wailing on the grip.  Keep the slides wet and allow time for the fluid to "penetrate".  You can use the cables on your bike without installing the carbs on the bike.  Use both pull and push cables.

DO NOT pry on the slides inside the carb throat!

[TwoTired]

Where could i get bigger slow jets?  or is that not possible?

 I've never known a source for replacement or alternate size press in slow jets for the PD 46 carbs.  However, there are similarly designed and shaped slow jets that have screw threads and a range of orifice sizes.   With these in hand, a suitable tap/taps can be employed to make the carb bodies accept the screw in type.  This ought to go a long way toward making these carbs idle and have better off idle response when using pod type filters.

Do make sure that the idle circuit in the carbs it clear, as well as the jets, though.  The passage way has 4 openings to verify flow; the jet hole, the air bleed at the carb mouth, the carb bore exit, and (with the Idle Mixture Screw (IMS) removed) that screw hole, too.

[750goes]

Good to see you back TT

 

nothing much has changed - I know a little bit more about electrics - thanks to you   

[edbikerii]

I think there is some confusion about the PD46A carbs.  Perhaps the x46A carbs in the chart are not the same as the PD46A carbs.  I think we need a new column in the FAQ chart for the PD46A carbs for the '77 CB550K.

I have two separate spare racks of PD46A carbs for 77 CB550s.  The full numbers on these sets are PD46AAOG and PD46AAOH.

On both of the PD46A carb sets the pilot jets were 42, the mains were 90 and the needle clips were in the 2nd position from the top.

I don't know what the float height spec is supposed to be from the factory, but they are currently set to about 12mm.

I would ordinarily assume that I got a carb set that had been messed with by a previous owner, but there are too many factors here.  The pilots don't have any marks on them from having been pulled before.  The mains are 90's, which would probably have been the first thing to be molested by a previous owner, if anything were done to these carbs.  The same configuration has appeared on two separate sets of carbs from completely different sources.

Take a look at reply #8 in the carb FAQ.  There is a chart of the stock settings for the PD46A carbs.  Noteably, the needle clip was third from the top in stock configuration.

However, with pods and non-stock exhaust you have to re-engineer nearly all the jetting parameters for a street bike, including the slow jet size, main jet size, main needle position, main needle size, main needle taper, and possibly even the throttle valve cutaway.

Hope you have a test track or a Dynomometer.  Or, you're in for a very long trail and error period 'til the carbs approach the streetabilty of the stock configuration.

Good luck!  You'll learn a LOT in the process.

[TwoTired]

I made the chart in the FAQ from two information sources:
The Honda Shop Manual Pg 178
And, a booklet from Honda titled "Honda Motorcycle Service specifications for all 1959- 1980 US models"

While the shop manual does not list carb setup numbers, the booklet does:  (PD46C for the 78 Model, x46A for the 77 model).

The booklet does not give main needle settings. (Isn't that convenient    )

The shop manual has a carb setting table For the 550/500 K3 , the latter being a european model.
This table lists #38 Slow jet and 3rd groove setting for the CB550K3, and #42 and 2nd groove setting for the CB500 K3, along with a 14.5 mm float height for both for 1977.
I do have PD46C carbs.  But, I have never seen x46A carbs, and have wondered if the x was a place holder designation used by the tech writer until firm info was received, and then printed anyway when the schedule deadline came and went.

Anyway, I tried to use documented Honda sources for chart information.

I can appreciate that you've found differences on the carbs you have.  I cannot explain them, nor do I discount them. 

But, do we want to change the FAQ chart based on examples found, or documented sources?  I can add another column to the FAQ easily enough, I suppose.  How do we access the certainty of the sampled data findings?  I'm uncomfortable with a sample base of two which seems contradictory to Honda data.
Might it be better to create an addendum post using sampled measurement and observation data rather than add a column to a chart using Honda references?

I've been out of town this last week, so forgive the response delay.  And, if this seems disjointed, it was kind of a long day.

Cheers,

[edbikerii]

I agree that using documented Honda sources would be ideal if they were known to be 100% accurate.  Unfortunately, these sources are known to be incomplete, at best.  It should at least be noted prominently in the chart that there are consistent exceptions, so as not to mislead the owner who has PD46A carbs.  Such notation would make the existence of an exceptions addendum useful.

I too thought that the x46A was meant to represent the PD46A, but that is clearly not the case, based on the empirical evidence (the two example sets of unmolested PD46A carbs with different jets - also produced by Honda).  The carbs themselves were produced by Honda, which in my mind at least, supercedes any documentation that was produced by Honda.

I find misleading or incomplete documentation very frustrating, if not downright dangerous.  For example, the float level spec in the Haynes manual is completely inaccurate for 1977 CB550K models.  The most careful, picky owner might just adjust his carbs to those specs and find himself unable to even get his bike to start.  Then he would have no idea what the correct spec is, and might be unabled to rectify the situation.  He might even remove the carbs and re-check the measurements several times to no avail.  If he were unlucky enough to get the bike to run in that condition, it would be exceedingly lean, and he just might end up with a holed piston.

[TwoTired]

Okay, a new day and some rest.

Thinking out loud here.

I agree many of the aftermarket manuals are misleading for the carb specs.  But, I'm not convinced yet that the carb chart is, or that the settings in the chart stated are "dangerous" for 77 CB550 owners with stock air filter and exhaust.
Has anyone ever found 77 CB550 carbs that were marked "X46A" ?  I haven't.  Nor have I seen them mentioned as found in forum postings.
The settings you've found seem to be the ones Honda used for the 500 version of the K3.  I would expect them to be marked differently than those for the 550 K3, but how?  If Honda had some sort of production marking issue, could they have installed CB500 carbs onto some 550s?
I'm not sure how to resolve this 30 years after the fact.  Perhaps we have the basis for a Forensic TV show? 

We ARE talking about stock settings.  To legitimize the settings you've found, wouldn't we need to find a 77 550 with stock pipes and air filter, and then do a Dyno test to confirm the carb settings are proper for that bike? That would be convincing!  It would also support many assumptions being made.

If I knew that the empirical cases you've found were 100% accurate, then the FAQ chart should certainly so state.  But, it seems to me that there are variables existant in all cases?

You could make a FAQ submission to capture your findings.  I simply don't know how to verify them from where I sit, or for that matter, the Honda source either.

I've been working on an expanded version of that chart, making measurements of needle tapers and orifice sizes throughout the carbs.  I have pretty reliable examples of the earlier carbs.  But, not the later ones, I'm afraid.  Would you be willing to measure and add your findings to the FAQ chart?  I was planning on notations of empirical measurements vs Honda source values.  Here's the list of data points.

627B    Carb setup number
Keihin (type 1)   Carb type
40      Slow jet
100  Main jet
#2.5 - 4th groove    Jet Needle and taper (Throttle valve)
272304   Jet needle number
5.57cm  Jet needle OAL
1.25mm  Jet needle diameter at tip
1.63mm  Jet needle diameter at 1mm
2.06mm  Jet needle diameter at 2mm
2.49mm  Jet needle diameter at 3mm
2.52mm  Jet needle diameter at 4mm
2.55mm  Jet needle diameter at 5mm
2.60mm   Needle jet orifice
0.9øX2  (1,2,3,4,5) Needle jet Air bleeds
1 +/- 1/8  Air screw opening (air Bleed)
none     Pilot screw opening (IMS)
#150   Main Air jet
#180   Slow air jet
22mm (0.89 in.)   Float Height

Or, perhaps the chart in the FAQ should be removed if it is too misleading?

Cheers,

[edbikerii]

My intention is to choose the better of the PD46A sets, install 114 mains, raise the needles two notches (clips in the 4th notches from the tops), and install them on my 1977 CB550K as a starting point for any further tuning that might be required.  I'm running pods and a Mac 4-1.  The bike is certainly running lean with the PD46C carbs that are on it now.  My goals are to smooth out the bogging in 1/2 to WOT operation, and to cool down the engine temps across the board.  I've always felt the bike ran too hot, even with the stock airbox and carbs.  Since I've got to screw around with jets to correct this anyway, I might as well improve the power and appearance with pods.

Here's more information for the improved FAQ chart, or whatever:

Both sets of PD46A carbs were respresented by sellers as having been from CB550s, one specifically from a '77.

Both sets have the later '77-'78 manifold spacing rather than the earlier spacing that would require the earlier manifolds.  The CB500 has the earlier spacing, I believe, although I've never had a CB500 to compare to.

Both sets had the '77 throttle return spring rather than the '78 throttle shaft concentric spring, as PD46C (on my '77 CB550).

[EDIT- added this line]  Both carb sets were purchased from sellers in the US.

PD46AA0G Carb Setup Number
Keihin
42 Slow jet
90 Main jet
Throttle valve id: 67A
Throttle valve overall length: 46mm
Throttle valve cutout: 2mm
Needle in second groove from top.
Needle ID: E2350 (very difficult to read positively, even on four different needles).
5.17 cm Jet Needle Overall length
~1.25mm at tip
~1.9mm at 1cm
~2.1mm at 2cm
~2.5mm at 3cm
~2.5mm at 4cm
~2.5mm Needle jet orifice (measured with modeling clay, then mic'ed
Air bleeds:  ?
No air screw.
IMS ~1.75 turns out, but who knows what the factory spec should have been?
Main air jet:  ?
Slow air jet:  ?
Float height: ~12mm

[edbikerii]

So, I pulled my PD46C carbs off, and noted 42 pilots and 90 mains, E2349F needle with clip in second groove from top, 67A throttle valve, float heights were ~14mm.

When I purchased the bike in '94, it had stock pipes and airbox, and I believe the carbs to have been mostly unmolested.

While cleaning these PD46C carbs up, I noted 3 missing idle mixture screw washers and one crushed/damaged o-ring.  So, I assume the PO messed around with them a little, probably trying to adjust the idle or something.  I've replaced those washers and the o-ring.  Now the screws have a noticeable effect on the idle mixture, whereas before they seemed to have no effect.

I've installed 114 mains, and raised the needles to the 4th groove from the top, but she bogged out heavily at 1/2 throttle and higher.  So, I dropped the needles back down to 2nd groove from top.  She still bogs out at WOT at around 7K rpm.  I'm not sure, but I suspect the 114 mains are too rich.

I've tried running plug chops, but I don't see any changes from one run to the next, no matter what throttle position I kill the engine, or needle position, or main jet size.  The plugs always look like the "perfect" image of a plug in all the plug charts.  Neither too rich nor too lean.  I'd love to hear from someone with real FIRST-HAND experience with plug chops who might tell me what I'm doing wrong, or what to really look for.  It is obvious that there is more to this than just comparing the plug to the plug charts.

[EDIT:  UPDATE!!!  JETTING FINALLY COMPLETE SEE: http://www.sohc4.us/forums/index.php?topic=22036.msg258435#msg258435 FOR DETAILS]