Author Topic: Update 550 76..smokes coming out exhaust  (Read 5186 times)

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Offline messeduptriple

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Update 550 76..smokes coming out exhaust
« on: May 10, 2012, 07:07:18 AM »
Ok so I got the bike back . It starts up fine, sounds just great, it idles fine.... But when it does it smmokes out some black in the exhaust... Nothing major but some is coming out for sure... I tapped on carb bowl lightly where it was leaking with flat head... Might have did something to the float that was leaking on the left cause there is no more leaking. The problem now is when I try and give it gas and go it clonks out when I go.... What may be the reason for this now? When it starts sometimes it wants to go but seems like the bike is on and off very softly, but it just dies then. What's going on now??
* note.... Just looked and leaking still out the left carb.

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« Last Edit: May 10, 2012, 07:28:00 AM by messeduptriple »

Offline messeduptriple

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Re: Update 550 76..smokes coming out exhaust
« Reply #1 on: May 10, 2012, 07:07:53 AM »
2nd that gas leak..still coming out..

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Offline Deltarider

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Re: Update 550 76..smokes coming out exhaust
« Reply #2 on: May 10, 2012, 07:13:21 AM »
Are your seals (in particular around float needle seat and main jet) sound?
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Offline Duanob

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Re: Update 550 76..smokes coming out exhaust
« Reply #3 on: May 10, 2012, 03:56:03 PM »
Can you pull your float bowls and make sure the floats aren't stuck or everything is working the way it should. I use a clear tube float level tester that works good, I don't have to take the bowls off for that.
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Offline TwoTired

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Re: Update 550 76..smokes coming out exhaust
« Reply #4 on: May 10, 2012, 04:25:55 PM »
Got a work stand so you can work on the bike upright?
Which carb is leaking?
If it is an outer carb you can pull the bowl off for a look-see inside.  Note that the bowl has molded stops for the float pins so they will stay in place.

Any crud in the bowl?  Stand pipe cracked?  If you hold the float up and turn on the gas, does it still leak fuel?
If not, how far down can you move the float before gas come out?  22mm?
Are you using the stock Honda float needles?

Some bikes leak when on side stand, but not when on the center stand.  Block your stand so the bike is upright.  Still leaking?

Throttle stumble:
How far are you turning the throttle to accelerate.  (Not going to accelerate if you snap it wide open from idle.)
What position/turns are the air screws set to?
What air filter are you using?

What is the hand signal for a right turn?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline messeduptriple

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Re: Re: Update 550 76..smokes coming out exhaust
« Reply #5 on: May 11, 2012, 07:58:28 AM »
Got a work stand so you can work on the bike upright?
Which carb is leaking?
If it is an outer carb you can pull the bowl off for a look-see inside.  Note that the bowl has molded stops for the float pins so they will stay in place.

Any crud in the bowl?  Stand pipe cracked?  If you hold the float up and turn on the gas, does it still leak fuel?
If not, how far down can you move the float before gas come out?  22mm?
Are you using the stock Honda float needles?

Some bikes leak when on side stand, but not when on the center stand.  Block your stand so the bike is upright.  Still leaking?

Throttle stumble:
How far are you turning the throttle to accelerate.  (Not going to accelerate if you snap it wide open from idle.)
What position/turns are the air screws set to?
What air filter are you using?

What is the hand signal for a right turn?
the stand is off. The right carb is leaking now. The bowls were clean when i pulled them out  last nite. Two  120 pilot jets were clogged. ..i cleaned them out. Yes stock needles. I turn  the throttle  just a bit and wants to cut out. The idle is loud and high and its still smoking the air screw meaning the rpm screw?  I dont know what this airscrew is? ? Im using a regular air filter in box.
Bent elbow arm up. ...then repositon arm to its regular  position. 

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Offline luap

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Re: Update 550 76..smokes coming out exhaust
« Reply #6 on: May 11, 2012, 10:03:18 AM »
Didnt you post the other day, something about carpy said to run 120? an questionable on what size idle jet you were running?  What size was the idle jet when you pulled them last night? IMO 120 mains for a almost stock configuration is to big, and some of the aftermarket pipes say they dont need to be rejetter, Id pull the carbs an see what you are working with Idle,main, needle clip position, cleaness, filter type oiled or not, bowl o rings,
is the smoke coming from the head or the tip
my 2 cents stock needle clip position, 105 main stock idle make sure carbs are clean , see how it rides then, an adjust a/f oil or oiless filter an adjust needle depending how it rides
75-550 ffsc sold, 78-550 diamonte sold, 125s grasshopper sold, 76-550 puma sold, 78-550 tracker sold, 74-550 verde diablo Sold, 74-550 Noemani finished trying to sell. 72 500 hartail in the works
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Offline messeduptriple

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Re: Re: Update 550 76..smokes coming out exhaust
« Reply #7 on: May 11, 2012, 11:17:23 AM »
Didnt you post the other day, something about carpy said to run 120? an questionable on what size idle jet you were running?  What size was the idle jet when you pulled them last night? IMO 120 mains for a almost stock configuration is to big, and some of the aftermarket pipes say they dont need to be rejetter, Id pull the carbs an see what you are working with Idle,main, needle clip position, cleaness, filter type oiled or not, bowl o rings,
is the smoke coming from the head or the tip
my 2 cents stock needle clip position, 105 main stock idle make sure carbs are clean , see how it rides then, an adjust a/f oil or oiless filter an adjust needle depending how it rides
[/quot
No carpy told me to run 120 ... now im asking since im getting some black out the exhaust  and it's  running  rich should i bump them back to  the 110 i had in  them? ? The bike is ideling hard and high on rpms ... it doesnt want to mellow out

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Offline matt mattison

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Re: Update 550 76..smokes coming out exhaust
« Reply #8 on: May 11, 2012, 11:46:01 AM »
My 75' CB550 with V-stacks and the Carpy pipe is running 38 pilot/slow and 110 main jets. I think that 120 main might end up being too fat. I think every jet size increase equals a 10% change. But all that doesn't matter because the mains only come on from 3/4 throttle on up. Your problems sound like its idle circuit related. You stated before your pilot was 120, but that can't be. I'm assuming you meant the mains were 120. You need to verify your pilot jet size and make sure you can see light through them. If you can't see through them, they are clogged. Make sure all passages are clean,if you haven't already. While you have your mains out again, I would pop those emulsion tubes out and clean them if necessary. The tower where the emulsion tube lives can be cleaned as well with a .22 caliber gun barrel brush and some carb cleaner. Most of this can be done with the carbs on the bike. And also ,do whatever Two Tired suggested
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Offline TwoTired

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Re: Re: Update 550 76..smokes coming out exhaust
« Reply #9 on: May 11, 2012, 12:19:39 PM »
Got a work stand so you can work on the bike upright?
Which carb is leaking?
If it is an outer carb you can pull the bowl off for a look-see inside.  Note that the bowl has molded stops for the float pins so they will stay in place.

Any crud in the bowl?  Stand pipe cracked?  If you hold the float up and turn on the gas, does it still leak fuel?
If not, how far down can you move the float before gas come out?  22mm?
Are you using the stock Honda float needles?

Some bikes leak when on side stand, but not when on the center stand.  Block your stand so the bike is upright.  Still leaking?

Throttle stumble:
How far are you turning the throttle to accelerate.  (Not going to accelerate if you snap it wide open from idle.)
What position/turns are the air screws set to?
What air filter are you using?

What is the hand signal for a right turn?
the stand is off. The right carb is leaking now.
Um, the bike has two right carbs.

The bowls were clean when i pulled them out  last nite. Two  120 pilot jets were clogged. ..i cleaned them out.
One of us is confused.  The stock pilot jets are #38.  How did you get 120 there?
If you meant the 120 as the main jet and it was clogged, the the smaller #38 has almost certain;y clogged, too.

Yes stock needles.
  I have to ask this, mostly becasue of the lack of detail you are providing and perhaps directing toward your bike.
How do you know you have stock slide needles?   Because you didn't replace them?  Have you checked each spring pin for relative rebound pressure?

I turn  the throttle  just a bit and wants to cut out.
Was this in association with the cold head pipes or before jet cleaning?

The idle is loud and high and its still smoking the air screw meaning the rpm screw? 
I dont know what this airscrew is? ?
Have you no manuals at all?  Even the crapy Clymer has a picture for those on the side of each carb.

Bent elbow arm up. ...then repositon arm to its regular  position. 
COOL! That's right!   ;D ;D


You are near the end of your project where details are very important to sort out all the changes you've made to the bike.  There is a running commentary in engineering circles that the last 10% of the project takes 90% of the time to sort out.
You are going to have to get detail oriented to sort out the remaining issues with your project.
We can only help if you share the details.  You are our eyes, ears, and trusted detail reporter.

I expect that once you have all the cylinders firing, the remaining throttle response will be corrected and possibly improved with an air screw/idle screw/pilot screw adjustment.

However, a 120 Main jet is likely too rich a mixture for your set up, once you are able to operate above 3/4 throttle position.  And, I wouldn't be a bit surprised to learn that it causes the spark plugs to soot up and foul, preventing spark.  Dead spark plugs are going to really interfere with fine tuning carbs for throttle response issues.

With the stock air box and paper filter, I'd expect a 105 (maybe 110) to be more in line with expectations.  I'd also project that the slide needles would work well at the 4th clip position from the top, and the idle air screws set to about 1 to 1 1/2 turns out from seated.
This is where *I* would start the tune process.  But, I would require that all cylinders be working before doing any "fine tuning" of the carbs.

Did you check for a cracked stand pipe, yet?

Do you have ANY sort of stand to work on the bike in an upright position?

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline OneWheelDrive

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Re: Update 550 76..smokes coming out exhaust
« Reply #10 on: May 11, 2012, 01:53:30 PM »
Jake, in a few days you should be receiving the carbs I rebuilt for ya.  They are stock jetted, clean, bench synced, and ready for install.  Throw those bad boys on there, should start right up!  If you're a little lean, either raise the needle clip one position, or up the main jet to 105 as suggested above (there's 100's in there now). 
1975 CB550 cafe
1971 CB500 stocker
2008 Ducati Hypermotard 1100S *sold*
1973 CB350F *sold*
1975 CB550K Project "Keeper" *sold*
2010 Ducati Monster S4RS *sold*
1976 CB360T *sold*
1974 CB550K *sold*
1973 CB750K *sold*
1978 CB550K *sold*
2007 Vespa LX150 *sold*

Offline messeduptriple

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Re: Re: Re: Update 550 76..smokes coming out exhaust
« Reply #11 on: May 11, 2012, 03:36:57 PM »
Got a work stand so you can work on the bike upright?
Which carb is leaking?
If it is an outer carb you can pull the bowl off for a look-see inside.  Note that the bowl has molded stops for the float pins so they will stay in place.

Any crud in the bowl?  Stand pipe cracked?  If you hold the float up and turn on the gas, does it still leak fuel?
If not, how far down can you move the float before gas come out?  22mm?
Are you using the stock Honda float needles?

Some bikes leak when on side stand, but not when on the center stand.  Block your stand so the bike is upright.  Still leaking?

Throttle stumble:
How far are you turning the throttle to accelerate.  (Not going to accelerate if you snap it wide open from idle.)
What position/turns are the air screws set to?
What air filter are you using?

What is the hand signal for a right turn?
the stand is off. The right carb is leaking now.
Um, the bike has two right carbs.

The bowls were clean when i pulled them out  last nite. Two  120 pilot jets were clogged. ..i cleaned them out.
One of us is confused.  The stock pilot jets are #38.  How did you get 120 there?
If you meant the 120 as the main jet and it was clogged, the the smaller #38 has almost certain;y clogged, too.

Yes stock needles.
  I have to ask this, mostly becasue of the lack of detail you are providing and perhaps directing toward your bike.
How do you know you have stock slide needles?   Because you didn't replace them?  Have you checked each spring pin for relative rebound pressure?

I turn  the throttle  just a bit and wants to cut out.
Was this in association with the cold head pipes or before jet cleaning?

The idle is loud and high and its still smoking the air screw meaning the rpm screw? 
I dont know what this airscrew is? ?
Have you no manuals at all?  Even the crapy Clymer has a picture for those on the side of each carb.

Bent elbow arm up. ...then repositon arm to its regular  position. 
COOL! That's right!   ;D ;D


You are near the end of your project where details are very important to sort out all the changes you've made to the bike.  There is a running commentary in engineering circles that the last 10% of the project takes 90% of the time to sort out.
You are going to have to get detail oriented to sort out the remaining issues with your project.
We can only help if you share the details.  You are our eyes, ears, and trusted detail reporter.

I expect that once you have all the cylinders firing, the remaining throttle response will be corrected and possibly improved with an air screw/idle screw/pilot screw adjustment.

However, a 120 Main jet is likely too rich a mixture for your set up, once you are able to operate above 3/4 throttle position.  And, I wouldn't be a bit surprised to learn that it causes the spark plugs to soot up and foul, preventing spark.  Dead spark plugs are going to really interfere with fine tuning carbs for throttle response issues.

With the stock air box and paper filter, I'd expect a 105 (maybe 110) to be more in line with expectations.  I'd also project that the slide needles would work well at the 4th clip position from the top, and the idle air screws set to about 1 to 1 1/2 turns out from seated.
This is where *I* would start the tune process.  But, I would require that all cylinders be working before doing any "fine tuning" of the carbs.

Did you check for a cracked stand pipe, yet?

Do you have ANY sort of stand to work on the bike in an upright position?

Cheers,
i will put the 110 back in. Nothing is cracked, the bowls were solid,  when i had it running it was starting to lightly  smoke out the front by the headers ...i think cause the damn bike was running  so high on rpms.  I couldnt get it to idle relaxed...it was only high rpms or nothing. 

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Offline messeduptriple

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Re: Re: Update 550 76..smokes coming out exhaust
« Reply #12 on: May 11, 2012, 09:01:36 PM »
My 75' CB550 with V-stacks and the Carpy pipe is running 38 pilot/slow and 110 main jets. I think that 120 main might end up being too fat. I think every jet size increase equals a 10% change. But all that doesn't matter because the mains only come on from 3/4 throttle on up. Your problems sound like its idle circuit related. You stated before your pilot was 120, but that can't be. I'm assuming you meant the mains were 120. You need to verify your pilot jet size and make sure you can see light through them. If you can't see through them, they are clogged. Make sure all passages are clean,if you haven't already. While you have your mains out again, I would pop those emulsion tubes out and clean them if necessary. The tower where the emulsion tube lives can be cleaned as well with a .22 caliber gun barrel brush and some carb cleaner. Most of this can be done with the carbs on the bike. And also ,do whatever Two Tired suggested
can I replace the main jets while carbs r still in the bike?

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Offline TwoTired

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Re: Re: Update 550 76..smokes coming out exhaust
« Reply #13 on: May 11, 2012, 11:19:12 PM »
can I replace the main jets while carbs r still in the bike?
It is possible with the right tools and mechanic's prowess.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.