Topic: Keihin 022a carbs on 1972 CB500

[yogi]

I just noticed that the carbs on my 1972 CB500 are Keihin 022A, not 627B. The specs look almost identical. Do you think this is a problem?

[calj737]

Nope, not at all.

[TwoTired]

Not a "problem", in that they will work.  But, unless you change the internal set up, they won't be ideal.

They both would need internal changes if there have been exhaust and intake tract differences from stock.

Cheers,

[yogi]

What would your guess the carb setup should be? The bike is stock except for some unknown 4 into 2 exhaust and dyna s electronic ignition. The pilot and main jets seem to be the same size from 022a to 627B, but the needle jet appears a little different.

[Scott S]

 I wouldn't worry about it. You're probably "close enough" to stock that it's not going to be a problem. If you REALLY want to know, you could check the needle clip position to be sure it hasn't been changed. Same with the idle mixture screw. And if you're inside the carbs to check the needles, verify that you have stock Keihin brass and jet sizes and check the float height.
 If it's running good now, you're not going to find some magical 5HP from messing with the carbs.

[Deltarider]

Setting 022A is close as it is, so I'd first ride it. Lots of folks like to go at the needles, doing plugchops and all. Maybe adjust the aircrews a bit. Just don't try to achieve a highest rpm at idle!!

[TwoTired]

What would your guess the carb setup should be? The bike is stock except for some unknown 4 into 2 exhaust and dyna s electronic ignition. The pilot and main jets seem to be the same size from 022a to 627B, but the needle jet appears a little different.

Can you find numbers stamped on the needles?

The stock tuning settings are in the small booklet pages below.  The booklet was intended for Honda dealer mechanics.

The 022A carb should have #38 pilots, rather than #40.

While the needle jet settings are the same for position, the needle size a shape are different between the two.  Due to the smaller displacement of the motor, the major diameter of the needles is slightly smaller on the 627B than for the 022A.  I could only find taper angle specs for the 022A needles, though.  I don't know if that is different between the 627B and 022A.
Also having effect, would be the mains emulsion tube dimensions.  Air bleed hole quantity, size, and position on the tube are of importance, for mixture ratios provided in throttle positions 1/8 to 3/4.

Also of note, that in the 50-ish years since the carbs were first sold, it is rare that these carbs haven't been apart before and had their internal parts touched, altered, or replaced.

Cheers,

[Deltarider]

What would your guess the carb setup should be? The bike is stock except for some unknown 4 into 2 exhaust and dyna s electronic ignition. The pilot and main jets seem to be the same size from 022a to 627B, but the needle jet appears a little different.

Can you find numbers stamped on the needles?

The stock tuning settings are in the small booklet pages below.  The booklet was intended for Honda dealer mechanics.

The 022A carb should have #38 pilots, rather than #40.

While the needle jet settings are the same for position, the needle size a shape are different between the two.  Due to the smaller displacement of the motor, the major diameter of the needles is slightly smaller on the 627B than for the 022A.  I could only find taper angle specs for the 022A needles, though.  I don't know if that is different between the 627B and 022A.
Also having effect, would be the mains emulsion tube dimensions.  Air bleed hole quantity, size, and position on the tube are of importance, for mixture ratios provided in throttle positions 1/8 to 3/4.

Also of note, that in the 50-ish years since the carbs were first sold, it is rare that these carbs haven't been apart before and had their internal parts touched, altered, or replaced.

Cheers,

Carbs 022A and 627B share exactly the same needle set and consequently their needles have the same size, same taper and should have the same number: 272304.
The practice of opening carbs and going at the needles maybe common in this site, not to say epidemic, outside this forum things are a bit more normal in my experience. Unless you have serious indications carbs have been opened by a PO, my advice remains: ride it first, tweek the airscrews maybe a bit and see where it gets you.

[TwoTired]

You are welcome to be misled by uninformed and inexperienced posters from outside the U.S.  (Who appears to have a vendetta against those in America.)

I will point out that the throttle valve jet needle is specified as #2.5 in the Honda shop manual chapter 4 above Fig, 184.  This manual began as a CB500 manual, which had 627B carbs later expanded to include the CB550 using supplement chapters.
In the chapter 16 Supplement, it states the 022A needles are 2.515.  Small dimensions can make a difference.

That is why I asked what numbers you have on the needles, since you say they are different.  They may not even be Keihin needles, depending on the number.  Aftermarket needles have been reported to have run time mixture issues.

Good luck with your choices!

[jonda500]

I have both 022A and 627B carb sets and they both came with the same needles and emulsion tubes (#272304) and #100 main jets. The 022A had #38 pilot jets rather than #40's that 627B's have. My 022A's came with aftermarket air screws so I don't know if they're different. When I got the 022A's the needle clips were in the middle slots...
John

[Deltarider]

You are welcome to be misled by uninformed and inexperienced posters from outside the U.S.  (Who appears to have a vendetta against those in America.)

I will point out that the throttle valve jet needle is specified as #2.5 in the Honda shop manual chapter 4 above Fig, 184.  This manual began as a CB500 manual, which had 627B carbs later expanded to include the CB550 using supplement chapters.
In the chapter 16 Supplement, it states the 022A needles are 2.515.  Small dimensions can make a difference.

That is why I asked what numbers you have on the needles, since you say they are different.  They may not even be Keihin needles, depending on the number.  Aftermarket needles have been reported to have run time mixture issues.

Good luck with your choices!

Unfortunately TT is adding confusion by bringing in the throttle valve. The throttle valves are identical on all oldstyle CB500/550 carbs (627B, 649A, 022A, 087A and 069A). Let's stick to the facts, shall we? Well, it seems not everybody is aware the Shop Manual has an error on p.165.
Over the left column in the Carburetor setting table you should read CB550 and not CB500.
Not only would it be unlogic to compare CB500 and CB550 carbs on that page - and perfectly logic to compare CB550(K) carbs to CB550F carbs - also... no CB500 models ever had the 022A carbs. I'd expect everybody knew by now, since I already pointed at that mistake at least three times. Moreover, parts lists are perfectly clear on all carb parts*. They're all here:  http://www.honda4fun.com/materiale-documentazione-tecnica/parts-list/parts-list-cb500 and
http://www.honda4fun.com/materiale-documentazione-tecnica/parts-list/parts-list-cb550
Yogi, although we still don't know for a fact that the venturis were identical, I think it's safe to assume your 022A carbs are very close to what you need. If we look at the specs of the 022A and the 627B resp. (the latter with the American setting), it would mean you'd only have to adjust the airscrews, if at all. That's all in all what I based my previous advice on: ride it first, tweek the airscrews maybe a bit and see where it gets you. Anyway, that's what I'd do.
* One mystery remains to be resolved however: the airscrews on the 087A carbs that were on the CB550K2. Why is it that particular parts list on p. C10 suggests the 087A had the same (solid) airscrew (16016-390-004) the F models had in their 069A carbs, where so far no owners of a K2 reported they actually have them but instead have the same crossdrilled (16016-323-004) airscrews the previous K models had? p.C10 in: http://www.honda4fun.com/pdf_parts_list/pdf_spac550/CB550-K0-K1-K2/CB550-K0-K1-K2_04.pdf Intriguing, isn't it?

[TwoTired]

Unfortunately TT is adding confusion by bringing in the throttle valve. The throttle valves are identical on all oldstyle CB500/550 carbs (627B, 649A, 022A, 087A and 069A). Let's stick to the facts, shall we?

DR should follow his own advice.  069A carbs certainly have different dimensions as those in 022A carbs, (personally measured) as well as different part numbers within his own provided references.  16012-323-004 vs 16012-390-004
069A needles are stamped 273004, whereas 022A needles are stamped 272304.  And guess what?  The ones I measured physically are made to different dimensions from each other, who'da thunk?.
I have not yet measured the 627B needles I have, and they are 700 miles away right now.  So, that will have to wait 'til I get there.

But, if you wish to rely on DR "facts", that's up to you.  It IS the internet, after all.

Well, it seems not everybody is aware the Shop Manual has an error on p.165.
Over the left column in the Carburetor setting table you should read CB550 and not CB500.
Not only would it be unlogic to compare CB500 and CB550 carbs on that page - and perfectly logic to compare CB550(K) carbs to CB550F carbs - also... no CB500 models ever had the 022A carbs.

More subterfuge by DR, conveniently avoiding the Cb500 specs on page 61 of the very same manual which state a different needle size.   Likely the results of only finding what you wish to find, to sort of support your argument.  Page 165 clearly refers to the 022A set up number, which I feel is the important part of the chart.  I've known about the cb500/CB550 misprint for over 20 years.  DR is often confused by reality.

However, since the manual has known flaws elsewhere, page 61 could also be in error, I suppose.  I'll measure the needles and note their stamped number when I get to them in breaks during my ongoing residence move.


Yogi, in rely #3 you stated the needle numbers you compared were different in your example carbs sets.  Would you tell us what those numbers are?

Cheers,

[Deltarider]

And now TT brings in the 069A needles. For what? It's not the subject at all, nor were the throttle valves. I leave it here. Every reader can see my remarks are consistent and can be checked. Those that want to know more about oldstyle CB500/550 carbs can do a Search with user: Deltarider. Over the years I've posted a lot on the CB500/550 carbs. Just an example: http://forums.sohc4.net/index.php/topic,108611.msg1223127.html#msg1223127 Moreover I cooperated to get all the info available for the whole world.
Yogi, I'm sorry you met so much distraction.

[TwoTired]

And now TT brings in the 069A needles. For what? It's not the subject at all, nor were the throttle valves. I leave it here.

I didn't bring it in, you did Dementedrider, with post #10 and your unsound "facts" stating all the needles were the same, representing your typical accuracy, or lack thereof.
If you'd read what I posted instead of trying in vain to be infallible, you might have noticed.
Rather frightening, you trying to be an educator, when you are so clueless.

Unfortunately TT is adding confusion by bringing in the throttle valve. The throttle valves are identical on all oldstyle CB500/550 carbs (627B, 649A, 022A, 087A and 069A). Let's stick to the facts, shall we?

Thus proving facts as DR presents are unsound.

[Deltarider]

I didn't bring it in, you did Dementedrider, with post #10 and your unsound "facts" stating all the needles were the same, representing your typical accuracy, or lack thereof.

Where did I say that? I said the throttle valves are identical on all oldstyle CB500/550 carbs.
All readers please take note of this: never, ever correct TT on anything, because he will hunt you for the rest of your life. He will react by creating mist (introducing throttle valves), more mist (introducing needles) then misquote you and if you don't give up simply because you're right, in the end he goes ballistic. TT, stop it, you're making a fool of yourself and it's not a nice sight.
The advice to Yogi, first to see if the right needles are in there, is absurd because it means a lot of work and as a 'bonus' you'll need to synchronise the carbs. Why wouldn't the right needles be in there? Why start with that suspicion, why start with the complicatest? Mount the carbs, ride the bike and go from there.

[TwoTired]

I didn't bring it in, you did Dementedrider, with post #10 and your unsound "facts" stating all the needles were the same, representing your typical accuracy, or lack thereof.

Where did I say that? I said the throttle valves are identical on all oldstyle CB500/550 carbs.

I freaking quoted it for you.  How can you be part of this forum and not be able to see or read?  Wait I get it.   It's a selective behavior.

The slide needles ARE the throttle valves.  Can't use semantics or misdirection to squirm out of that one.

All readers please take note of this: never, ever correct TT on anything, because he will hunt you for the rest of your life.

More examples of not taking your own advise.
Look in the f'ing mirror for an example of that very behavior.  How long have you had Tourette Syndrome?

He will react by creating mist (introducing throttle valves), more mist (introducing needles) then misquote you and if you don't give up simply because you're right, in the end he goes ballistic. TT, stop it, you're making a fool of yourself and it's not a nice sight.

The day I take advice from you is the day I stop breathing.  You have nothing but inane foolish argument to offer me.
The fact that you aren't enjoying this stupid farce is its own reward.  But, you will perpetuate the farce, as it is your way.  I'm only reflecting your very own past behavior.

In fact, you aren't right, you're wrong, (yet again) and are squirming about trying to avoid that realization.  What's sad is you screw up so many threads with your own foggy conceptualizations, and unsupported, unfounded, and illogical personal opinions.

The advice to Yogi, first to see if the right needles are in there, is absurd because it means a lot of work and as a 'bonus' you'll need to synchronise the carbs. Why wouldn't the right needles be in there? Why start with that suspicion, why start with the complicatest? Mount the carbs, ride the bike and go from there.

More misguided irrational "advice".
Yogi already had a look at the needles.  Did you miss that detail, too?   How sad.  Must add A.D.D. to your list of aberrant behaviors.

[Deltarider]

The slide needles ARE the throttle valves.

No, they are not. All CB500/550s with oldstyle carbs (022A, 627B, 649A, 087A and 069A) have the same throttle valve (partsnumber: 16111-323-004).
The needle sets for "K" and "F" models differ however and so have different partnumbers: carbs for the "K" models (627B, 649A, 022A and 087A) have needle set 16012-323-004 (in the needle you'll find the number 272304 stamped), the 069A carb for the "F" models have needle set 16012-390-004 (in the needle stamped the number 273004).

Yogi already had a look at the needles.  Did you miss that detail

Yes, I missed that actually. I'm still studing what "appears" in

but the needle jet appears a little different.

means. It doesn't seem he had a good look at it yet, now did he? I mean, a 272304 needle obviously will have 5 slots, a 273004 needle only 4 and, as said, the numbers will be on the needles. So, I'm still puzzling what his "appears a little different" is based on.

[yogi]

By needles being a little different from 627B and 022A I was going by the carb specs table on this site. The actual needle currently in there is a 272304 with the clip set on the 2nd ring from the bottom.

[yogi]

By the way. Here are some more details...I can't seem to get the bike idle downmuch below 3000, which is why I am digging into the carb issue. I don't appear to have any leaks (using carb cleaner test). Checked the timing already (new coils, plugs, and dyna-s ignition. The #2 carb was leaking a bit of gas through the overflow the last time I had the bike running, although the idle problem was happening before (and before the new ignition). Main Jet =100, slow jet = 40, exhaust = 4 into 2. The carbs look fairly new compared to the rest of the bike. I do know that the previous owner let the bike sit for a year. I took the carbs off once. #1 was a little gun ked up, but not too bad. The rest were remarkably clean. Not knowing what else to do, I ordered carb rebuild kits and was planning on rebuilding all of them anyway just to eliminate that as a source of the problem. I was wondering if there was anything else I should do with the jets etc. while I have the carbs broken down. Kinda frustrated. I've been messing with this bike for a few months now and would like to get it on the road, bit I am reaching the limits of my newbie know how.

[Deltarider]

By needles being a little different from 627B and 022A I was going by the carb specs table on this site. The actual needle currently in there is a 272304 with the clip set on the 2nd ring from the bottom.

That's - as expected - the correct needle and the standard setting for the 022A carbs. Although most markets had the needle in 3rd (middle) position in the 627B carbs, in US an American Honda booklet for some reason prescribed to have them in 4th (from top) with the airscrews two turns out (where other markets with the needle in 3rd position had them one turn out). That's why I said your carbs are as close as possible.

[Deltarider]

Your 022A carbs seem to be set the same as the 627B for the US. We would like to know whether you installed genuine Keihin brassware or aftermarket (like Keyster). The general advice here is to stay stock. After all, these parts hardly wear if at all. If you have replaced by aftermarket and you still have the originals, I'd return to stock. If you have the carbs on the table, so to speak, you could check the floatheights as described on p. 60 of the Honda Shop Manual CB500-CB550. To be sure you could later doublecheck with the clear tube method. You could polish the swivel pins (very lightly) so they'll move OK. Also check the float pins are not sticking.
About your high idle. Could it be that as a result of your syncing, the slides can't go all the way down anymore? In that case you have to readjust and see to it, by turning the big idle adjuster screw, that slides can go all the way down.
Are there any "extra" inline fuel filters that can hinder a correct fuel flow? I recommend to have the fuellines at standard length: 18 and 30 cm for the CB500 models with the old type petcock that is probably on yours and 17 and 28 cm for the newer type petcock. This with a standard ⌀ of 5,5 mm and you'll have no chance of any kinks. BTW, does your ignition still has the stock mechanical advancer? If the advancer doen't work correctly (old grease that's gone hard for instance), that also can result in a high idle. Some say sloppy springs also can hinder the advancer to retard to 'idle', I myself have not experienced that yet.

[yogi]

Lots of excellent advice. Thanks. I know what I am doing this weekend.

[yogi]

Thanks for all the help. It turns out that, as Deltarider pointend out, the slides were so out of wack that they weren't going down far enough. I bench synced them with the light method, and then synced them with a manometer on the bike. It is running beautifully now. The high idle problem is gone.