Author Topic: 550K1 - carb questions (022A)  (Read 6572 times)

Offline Erny

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550K1 - carb questions (022A)
« on: June 22, 2019, 11:44:07 AM »
Starting new thread as it seems I will have more questions. Sorry for them, going to "play" with carb for the first time..
Appologize if this has been answered elsewhere many times already

So let's start:
- is it possible to check and change needle settings (to see which notch is used) without complete disassembly? I'm afraid answer is no, but just in case ;)
- on my carb set, after I removed main jets and turned carbs over emulsification tube dropped out just by gravity.. Just on 1st carb. Tube is very loose in rge hole.. Is that ok? No impact on carb function?
- mixture screw - I suppose it changes air flow, correct? So turning in makes mix richer?
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Offline deltarider

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Re: 550K1 - carb questions (022A)
« Reply #1 on: June 23, 2019, 07:44:16 AM »

- is it possible to check and change needle settings (to see which notch is used) without complete disassembly? I'm afraid answer is no, but just in case ;)

There's a vid somewhere on youtube. Anyway, you do NOT have to separate carbs from eachother.
Quote
- on my carb set, after I removed main jets and turned carbs over emulsification tube dropped out just by gravity.. Just on 1st carb. Tube is very loose in rge hole.. Is that ok? No impact on carb function?
That's not abnormal at all. On mine they either come down by gravity or when helped a little by inserting a wooden toothpick or whatever from below, cant it and then wiggle it out. That's normal, I never had to tap them out from above. 
Quote
- mixture screw - I suppose it changes air flow, correct? So turning in makes mix richer?
Correct.

Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #2 on: June 23, 2019, 12:30:02 PM »
Many thanks for the answers!

BTW, isnt there detailed step-by-step instructions how to dissassembly and reassembly these carbs?
I have in mind something I found for PD42A carbs here : http://forums.sohc4.net/index.php/topic,146893.0.html
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Offline Seabeowner

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Re: 550K1 - carb questions (022A)
« Reply #3 on: June 23, 2019, 01:05:57 PM »
I found this on the net:
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #4 on: June 23, 2019, 02:11:01 PM »
Another 2 questions:
- what's the length of fuel hoses from carbs to cock?
- is it possible to replace hoses (installation especially) provided I use genuine Honda (got from 4into1 declared as genuine) without separating carbs from stay plate?
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Offline Bryanj

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Re: 550K1 - carb questions (022A)
« Reply #5 on: June 23, 2019, 04:38:16 PM »
You can even replace the hoses with the carbs on the engine if you have small flexible hands, hose lengths are quotef in parts book.

Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #6 on: June 23, 2019, 09:43:22 PM »
Thanks for all replies.

Just finished another round of carbs removal, opening, cleanup (it was clean anyway).
Carbs set are freshly rebuilt by Gerben - blasted from out and in, very clean. Jets 40/100.

Why I was doing it:
- engine don't start on choke, only without with certain trottle, after some warmup, it idles well. When using choke it dies (looks too rich when choke is engaged). Apart of that, when warm, egine idles and starts well, I feel too rich mix on low revs, from mid-high revs it pulls OK I guess (this is my first 550, so cannot compare)
- Cabs were leaking

What I did:
- removal and clenup of all what I could (without separation of the carbs and w/o taking out slides and needles. According to Gerben, needles and emulsification tubes are Keihin genuine and set on 4th groove
- I changed slow jets from 40 to 38 genuine Keihin

After assembly:
- bike still does not start on choke  >:(, so no improvement
- carbs are not leaking now  :)

I tried to remove filter element (replica from cmsnl) hoping for leaner mix, but no improvement too
Static ignition set OK, valves adjusted too.

Any advice what else can be wrong?
I reallly dont know what to do  :'( :'( :'(
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Offline paulbaker1954

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Re: 550K1 - carb questions (022A)
« Reply #7 on: June 24, 2019, 08:58:53 AM »
I am not sure what your real problem is here, you say bike wont start on choke but you are obviously able to start it, so is the issue that it is harder to start than you would expect only from cold.

I am assuming the chokes are operating properly as Gerben has rebuilt the carbs and I am also assuming the pilot air circuits are clear and the pilot jets are clear.

Are you using the correct starting procedure, below is what the original Honda owners manual recommends

COLD ENGINE STARTING
PROCEDURE
1) Turn the fuel tank valve to the "ON" position.
2) Insert the key into the main switch and turn to the "ON" position. At this time, observe the GREEN neutral indicator lamp on the lamp cluster. The lamp will be lighted when the transmission is in the neutral position. Also at this time the RED oil pressure warning lamp should be lighted. If the lamp fails to come on, the connection should be checked for an open circuit and the bulb checked and replaced if burned out.
3) Make sure that handle grip ignition switch is in the "ON" position.
4) Position the choke lever to the full closed position.
5) Twist the throttle grip inward slightly and depress the starter button. If the engine does not start within 5 seconds, release the starter button and allow the starter motor to rest for approximately 10 seconds before pressing the starter button again. If the engine does not start readily with the electric starter, to prevent excess battery discharge, use the kick starter pedal to start the engine. If the engine fails to start after several repeated attempts, turn off the main switch and lower the choke lever to the full open position, twist the throttle grip inward fully and crank the engine using either the electric starter or the kick starter pedal. This is then followed by turning the main switch to the "ON" position and following the starting procedure out-lined in steps 1 through 5, however, at this time the use of the choke is not necessary.
6) After the engine starts, operate at approximately 2,000 rpm until the engine will properly respond to the throttle with the choke open.

You also say that when warm it runs and idles well which would seem to indicate that the idle circuits and pilot jets etc in the carbs are all OK.

My 500 was never been a brilliant starter from cold and always needed a few cranks and throttle opening to get going. This has got better since moving over to a Boyer Ignition system using the Boyer Micro Coils. This led me to believe my starting issue was more down to maybe old weak coils rather than a carburation problem.

Here is my recommendation

1) Make sure there are no air leaks at the carb to head rubber joints
2) Are you sure you dont have a restriction in the fuel lines ( I had a strange problem with my old petcock that was strangling the fuel flow). I found this because if i turned the fuel on and then left the bike for 5 minutes this gave time to fill the float bowls and starting was much easier. Have you tried just  directly connecting an external auxiliary fuel tank to eliminate any such issues
3) May be worth changing points and condensors
4) Try another set of coils if you are using the original ones
5) You said you used a 38 pilot jet but I thought the right one was 40 (that said I have 627 carbs)
6) Make sure this is not an ignition problem rather than a carb problem



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Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #8 on: June 24, 2019, 09:48:59 AM »
Hi Paul
thanks for reply!

Yesterday evening I opened (yes, for the first time  ::)) manual to my CB550K1, reading the cold start procedure. Seems I had different expectations from how starting cold engine...
but point to point answers to your post:

I am not sure what your real problem is here, you say bike wont start on choke but you are obviously able to start it, so is the issue that it is harder to start than you would expect only from cold.
Yes, I can start, but impossible without trottle opening. When I open trottle its starts well without choke, but then I need to keep trottle open till it is warm enough to keep idling itself w/o trottle. If I use choke I need to use trottle too, but it starts much harder and does not respond trottle well (too rich mix).
Normally choke should make mix richer but in my case looks too much???
Another example, after I start w/o choke, while keeping engine alive with trottle to warm it up I engage choke (even partially), RPMs goes down, engine tends to stop / runs hard (too rich symptom)

I am assuming the chokes are operating properly as Gerben has rebuilt the carbs and I am also assuming the pilot air circuits are clear and the pilot jets are clear.
Yes, I confirm chokes operates properly, all pilot circuits are clear and jets are new genuine Keihin 38

Are you using the correct starting procedure, below is what the original Honda owners manual recommends
After reading manual and your post seems not really  :)

COLD ENGINE STARTING
PROCEDURE

...

4) Position the choke lever to the full closed position. Yes
5) Twist the throttle grip inward slightly and depress the starter button. I did not do this as part of procedure, but finally was doing so as the only way to start  ;D
Honestly, I expected I should only use choke and engine will run on higher RPMs, like my CB750 K7....
6) After the engine starts, operate at approximately 2,000 rpm until the engine will properly respond to the throttle with the choke open. Does this means I need to keep trottle open for some time to make engine warmer? But this can be quite some time... strange to me, I really expected that no trottle needed to warm-up using choke. This is not really very user friendly

You also say that when warm it runs and idles well which would seem to indicate that the idle circuits and pilot jets etc in the carbs are all OK. Exactly. BUT, when riding it, I feel that when trying to accerate from lower RPMs, engine suffers from too rich mix till it reaches higher RPMs.


Here is my recommendation

1) Make sure there are no air leaks at the carb to head rubber joints Rubber joints looks good and tight, I don't know how to test better. But if they would not be tight, mix should be leaner, which is not my case
2) Are you sure you dont have a restriction in the fuel lines ( I had a strange problem with my old petcock that was strangling the fuel flow). I found this because if i turned the fuel on and then left the bike for 5 minutes this gave time to fill the float bowls and starting was much easier. Have you tried just  directly connecting an external auxiliary fuel tank to eliminate any such issues Yes, I'm sure there is nothing blocking. Petcock is new (Honda), new hoses...
3) May be worth changing points and condensors I will, but normally this does not explain my symphoms
4) Try another set of coils if you are using the original ones Don't have spare set, but again I don't think this can cause my issue
5) You said you used a 38 pilot jet but I thought the right one was 40 (that said I have 627 carbs) According to specs, 022A, model year 1975 shall have 38
6) Make sure this is not an ignition problem rather than a carb problem
[/quote] as points 3&4 above

All in all, it still looks to me choke is completely useles (maybe can help in really cold weather?)
Are there any other carbs on later 550s that are better for cold start? (550F?)
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Offline K2-K6

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Re: 550K1 - carb questions (022A)
« Reply #9 on: June 24, 2019, 10:14:40 AM »
Unsure of choke application on this carb set,  don't think it lifts throttles as well as making richer?

K7 definitely lifts throttles with choke application,  manual allows nearly 3000rpm for running on choke so it's quite a bit of throttle applied when set. So fundamentally different from this one in discussion.

All the symptoms seem to agree with your feeling of running rich. The exhaust would smell of fuel too if that's the case.

You say that needle clips are in fourth position,  is that 4 from top of needle or 4 up from bottom position?

Suggestion if not like this,  put needle clips in fourth slot from bottom of needle (lowers needle to make leaner) then turn idle air screws out 1/2 turn from where they are.

You will need to use throttle while it warms up on this I believe.


Offline paulbaker1954

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Re: 550K1 - carb questions (022A)
« Reply #10 on: June 24, 2019, 10:28:46 AM »
Unsure of choke application on this carb set,  don't think it lifts throttles as well as making richer?

K7 definitely lifts throttles with choke application,  manual allows nearly 3000rpm for running on choke so it's quite a bit of throttle applied when set. So fundamentally different from this one in discussion.

All the symptoms seem to agree with your feeling of running rich. The exhaust would smell of fuel too if that's the case.

You say that needle clips are in fourth position,  is that 4 from top of needle or 4 up from bottom position?

Suggestion if not like this,  put needle clips in fourth slot from bottom of needle (lowers needle to make leaner) then turn idle air screws out 1/2 turn from where they are.

You will need to use throttle while it warms up on this I believe.

Yes on the 550 there is no throttle speed increase mechanism like you normally find on other carbs.

I normally use choke open to start and once running close chokes to about half way whilst it warms up. I do NOT need to keep the throttle open though whilst warming up so there is something not right with your setup. Moving the clip will not (I don't think) help as the needle position only starts to have effect at higher revs. That said I run mine in the middle position so you may want to change them ans see if it has any impact.
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Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #11 on: June 24, 2019, 10:45:19 AM »
Unsure of choke application on this carb set,  don't think it lifts throttles as well as making richer?

K7 definitely lifts throttles with choke application,  manual allows nearly 3000rpm for running on choke so it's quite a bit of throttle applied when set. So fundamentally different from this one in discussion.

All the symptoms seem to agree with your feeling of running rich. The exhaust would smell of fuel too if that's the case.

You say that needle clips are in fourth position,  is that 4 from top of needle or 4 up from bottom position?

Suggestion if not like this,  put needle clips in fourth slot from bottom of needle (lowers needle to make leaner) then turn idle air screws out 1/2 turn from where they are.

You will need to use throttle while it warms up on this I believe.

That's very good point, I did not realise before that K7 lifts trottles. That would explain why I need to use trottle

And yes, exhaust smells of fuel a lot

Concerning needles - honestly, I just rely on info double-confirmed by Gerben - that needles are 4th groove from top and they are genuine Keihin together with emulsification tubes. I did not checked that personally, as was too lazy (and under time pressure) to disassembly carbs.
What I can say they all looks to be the same settings (I saw needles sat equally in each tube when I removed main jets)
« Last Edit: June 24, 2019, 10:54:11 AM by Erny »
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Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #12 on: June 24, 2019, 10:52:50 AM »

Yes on the 550 there is no throttle speed increase mechanism like you normally find on other carbs.

I normally use choke open to start and once running close chokes to about half way whilst it warms up. I do NOT need to keep the throttle open though whilst warming up so there is something not right with your setup. Moving the clip will not (I don't think) help as the needle position only starts to have effect at higher revs. That said I run mine in the middle position so you may want to change them ans see if it has any impact.

"I normally use choke open to start and once running close chokes to about half way whilst it warms up" - do I understand you start engine like me, e.g. w/o choke use (= choke open) and then you use it halfway? Or wise versa, meaning you engage choke fully (= flaps are fully closed, so restricting air and making mix richer)? Sorry for such question, I'm not native english speaker  :D
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Offline paulbaker1954

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Re: 550K1 - carb questions (022A)
« Reply #13 on: June 24, 2019, 10:59:43 AM »

Yes on the 550 there is no throttle speed increase mechanism like you normally find on other carbs.

I normally use choke open to start and once running close chokes to about half way whilst it warms up. I do NOT need to keep the throttle open though whilst warming up so there is something not right with your setup. Moving the clip will not (I don't think) help as the needle position only starts to have effect at higher revs. That said I run mine in the middle position so you may want to change them ans see if it has any impact.

"I normally use choke open to start and once running close chokes to about half way whilst it warms up" - do I understand you start engine like me, e.g. w/o choke use (= choke open) and then you use it halfway? Or wise versa, meaning you engage choke fully (= flaps are fully closed, so restricting air and making mix richer)? Sorry for such question, I'm not native english speaker  :D

I normally start with choke fully engaged (ie flaps fully closed (lever in fully up position) and then lower to around halfway once running.

As these bikes dont have a device to increase throttle with choke movement they rely on you to do that !!!
If you think there's light at the end of the tunnel it's usually another train !!

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Offline Erny

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Re: 550K1 - carb questions (022A)
« Reply #14 on: June 24, 2019, 11:24:14 AM »
OK, now it is clear.
So I still have some issue to fix  :'(
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