Topic: CB550 K3 1977 model - carb jets

[Lars]

I have been working a lot on carbs to the CB 550 1974 - 1976 models, but the other day I was delivered a carb set for the CB 550 K3 1977 model. Helping a friend out. They are pretty different and I have no shop manuals for it. Nevertheless, it did not take me that long to competely disassemble them, that is usually the easy part, right?!
My question is regarding the jets. Beside the main jet, I am used to find a slow jet wich I can screw out with a flat iron. On this 1977 model, it seems to be a slow jet, too, but not to be screwed in, stamped #42. Tried carefully to pull it out, but it is stuck. Has a tiny hole in the bottom of it. Oustide the carb float bowl, there is another needle/jet, might be the air flow adjuster.
Anybody that can enlighten me, and point me to some exploded pictures and part numbers, instructions how to proceed regarding that "slow jet" part? Lars

[TwoTired]

Those carbs have PD on the sides.
The pilot jets are pressed (swaged) into the carb bodies as an interference fit.  They can still be removed by pulling them straight out, then cleaned, and tapped back into position.

The screw in front of the bowls is the Idle Mixture Screw.  It operates opposite the earlier Air bleed screws; turn in for learner and out for richer.  It has a rather limited range, though.  Only lightly seat that screw, it can jam and break off due to its shallow taper.

The Honda shop manual supplements  (chapter 19, I think) has info and pics about the 77-78 CB550 K3 carbs.

Cheers,

[Lars]

Thanks for the update, still a couple of questions:

1. What to you mean by the abbreviation PD?
2. The pilot jets #42, are they still available if completely clogged? I was afraid of pressing too hard around the jet, as it is brass. Could maybe press so hard, that the tiny channel inside it will deform??
3. Do you know the standard setting for the Idle mixture screw?

Thanks,
Lars

[bollingball]

may find parts here.
http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1107

[Lars]

This part from Siriussonic says #35 for this bike, the ones in the carb says #42. Makes me wonder if there are different carb models for this bike, or if the slow jets installed are non originals?

[crotella18]

Just to chime in,  I recently took apart the carbs on my 77 K3 and I too had the #42 push-in slow jets.  According the the manual the 550K3 is supposed to have a #38 slow, the CB500K3 has #42s.

However in what I have seen here, the CB550K3 appear to all have the #42 slows...maybe someone with more experience can say for sure if the CB550 K3s came with the #42 from the factory...?

To assist you, I soaked the carb bodies in simple green for about 24 hours then gently pulled the slow jets out with pliers making sure to not exert a lot of crushing force.

Hope this helps somewhat...

This part from Siriussonic says #35 for this bike, the ones in the carb says #42. Makes me wonder if there are different carb models for this bike, or if the slow jets installed are non originals?

[TwoTired]

1. What to you mean by the abbreviation PD?

Look at the sides of the carb bodies.  They have PD cast into them.  (See Pic)

2. The pilot jets #42, are they still available if completely clogged?

I haven't found a direct replacement source.
I also haven't found one that couldn't be cleaned with patience and thoughtful application.
The internal orifice is .42 mm.  So, certainly don't force anything larger than that through them.  I have made a small paddle drill from a guitar string for some.  Peen the end of the string wire flat.  Measure the resultant width with a caliper and then auger out the blockage, (IF and only if carb cleaner soaking doesn't clear the blockage.)
I won't soak metal parts in acid or base solution for any length of time more than 5 minutes or so.  Such cleaners dissolve metal as well as the deposits.  There are dedicated carb cleaner solvents available that are PH neutral, yet still dissolve the deposits.

I was afraid of pressing too hard around the jet, as it is brass. Could maybe press so hard, that the tiny channel inside it will deform??

I use a soft jawed parallel pliers for this task.  (See second pic of pliers and jet)
However, others have reported using leather pads in regular pliers to remove the jets.
Installation is just by tapping them in with a small hammer or screwdriver handle.

3. Do you know the standard setting for the Idle mixture screw?

The Honda shop manual states that the usual setting is at 1 1/2 turns (from lightly seated).
They also say they should be adjusted for max idle speed.  The adjustment is interactive with the idle speed knob. Mixture screw speed increases are countered with idle knob adjustment to keep the speed @ 1050 RPM.

Cheers,

[Lars]

Thanks for all the replies guys, I will go ahead tonight with my plier(s) and see if I can persuade the slow jet to see daylight again The guitar string trick in a small drill might work nice, doesn't use my guitar much anyways...

Cheers,

PS: Still need a CB 550 1974-1976 frame with title, if anyone comes across something like that. Got a bent frame at home after a test I don't want to tell you too much about...but I have realised that Buss Lightyear in "Toystory" and I have something in common...neither of us can fly...