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Author Topic: '74 CB550 idles fine then dies off later  (Read 2470 times)

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Offline Jimsun

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'74 CB550 idles fine then dies off later
« on: April 12, 2014, 03:56:35 PM »
At random times (8/10) the bike would idle at 1.7krpm and then it would then stall. I have to constantly either apply throttle or keep the rpm around 2k rpm or it'll stall if i let it idle on some occasions.

I have recently cleaned the carbs and when I opened up the bowls, they were pretty clean. I have synched the carbs before and i have resynch it to check if it's still around the same range and it's still the same except for one(?).

I have a video of the bike idling fine with the carbs synch hooked up. She is idling in the right range I believe.

http://youtu.be/UKTo9EmBSLQ

Also, when i removed my carbs, i saw green liquid (see pic below). Is this normal.

Anyone have any idea of why it would randomly stall when it's idling?
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Offline LesterPiglet

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Re: '74 CB550 idles fine then dies off later
« Reply #1 on: April 12, 2014, 04:21:05 PM »
Godsavus that sounds like a tractor. Something is badly wrong there. Never mind what the rev counter says, turn your idle screw up until you get a stable idle then do your carb sync. I'm not sure if I'm hearing a blow out or your clutch rattling.
No idea about the green.
When you say you cleaned the carbs did you remove all jets and the emulsion tubes and check them? If you didn't then the carbs aren't clean.
« Last Edit: April 12, 2014, 04:32:17 PM by LesterPiglet »
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline LesterPiglet

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Re: '74 CB550 idles fine then dies off later
« Reply #2 on: April 12, 2014, 04:44:02 PM »
It should sound more like this.

CB550 four walk around + idle


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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline Jimsun

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Re: '74 CB550 idles fine then dies off later
« Reply #3 on: April 12, 2014, 05:22:34 PM »

Quote from: LesterPiglet on April 12, 2014, 04:21:05 PM
Godsavus that sounds like a tractor. Something is badly wrong there. Never mind what the rev counter says, turn your idle screw up until you get a stable idle then do your carb sync. I'm not sure if I'm hearing a blow out or your clutch rattling.
No idea about the green.
When you say you cleaned the carbs did you remove all jets and the emulsion tubes and check them? If you didn't then the carbs aren't clean.
I thought 1.5k was the range for idling?

Yep literally took it apart and until you cant take it apart anymore.
Quote from: LesterPiglet on April 12, 2014, 04:44:02 PM
It should sound more like this.

CB550 four walk around + idle

Whats the rpm on that bike?
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Offline LesterPiglet

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Re: '74 CB550 idles fine then dies off later
« Reply #4 on: April 12, 2014, 05:24:13 PM »
As i said, ignore your rev counter. Are you sure it is accurate? I've lived without one since 86.
I'd guess thats about 1200.
If you disregard the numbers and listen to the engine that's all you need.

Your rev counter is pointing at 1200 btw. Idle speed should be around 1000 I believe.

I watched your video again. Is #1 cylinder even firing?
« Last Edit: April 12, 2014, 05:31:33 PM by LesterPiglet »
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline Jimsun

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'74 CB550 idles fine then dies off later
« Reply #5 on: April 12, 2014, 05:41:21 PM »
Quote from: LesterPiglet on April 12, 2014, 05:24:13 PM
As i said, ignore your rev counter. Are you sure it is accurate? I've lived without one since 86.
I'd guess thats about 1200.
If you disregard the numbers and listen to the engine that's all you need.

Your rev counter is pointing at 1200 btw. Idle speed should be around 1000 I believe.

I watched your video again. Is #1 cylinder even firing?
yes it fires & the header gets hot evenly.

Idling wise it sounds good at around 1.8-2k
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Offline LesterPiglet

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Re: '74 CB550 idles fine then dies off later
« Reply #6 on: April 12, 2014, 05:46:46 PM »
I would set your idle higher and try resyncing your carbs. As they come in to tune the revs will usually rise. You can adjust your idle to a satisfactory level as you sync.
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline LesterPiglet

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Re: '74 CB550 idles fine then dies off later
« Reply #7 on: April 12, 2014, 05:59:05 PM »
You can hear the idle on mine at the start of this video.

Modified Motad Honda CB550F
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline Jimsun

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Re: '74 CB550 idles fine then dies off later
« Reply #8 on: April 12, 2014, 06:19:18 PM »

Quote from: LesterPiglet on April 12, 2014, 05:59:05 PM
You can hear the idle on mine at the start of this video.

Modified Motad Honda CB550F
thanks lester
Ill try changing the idle at a higher rpm

The tach is stock. Also, the cable is new. Maybe i need to grease/lube the cable for better response/reading?
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Offline calj737

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Re: '74 CB550 idles fine then dies off later
« Reply #9 on: April 12, 2014, 06:22:12 PM »
What cleanser did you use to clean your carbs? That "green" stuff looks like cleanser being puked into the combustion chamber, and not being burned off. Any chance you didn't get them clean, rinsed, and fully dried out before you reassembled them?

Or, what oil are you running in that bike? If it's not cleanser, it would only likely be oil passing the guides or leaking into the intake chambers. Have you checked your plugs since this stalling began?
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'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Jimsun

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Re: '74 CB550 idles fine then dies off later
« Reply #10 on: April 12, 2014, 06:33:33 PM »

Quote from: calj737 on April 12, 2014, 06:22:12 PM
What cleanser did you use to clean your carbs? That "green" stuff looks like cleanser being puked into the combustion chamber, and not being burned off. Any chance you didn't get them clean, rinsed, and fully dried out before you reassembled them?

Or, what oil are you running in that bike? If it's not cleanser, it would only likely be oil passing the guides or leaking into the intake chambers. Have you checked your plugs since this stalling began?

I cleaned the carbs using pinesol. Then i used air compressor to clean and dry. After which i used a carb cleaner spray. Then i used the air compressor again. I installed them together afterwards.

The oil i use is mineral base 10w-40. It is colour light brown. Its a motorcycle wet clutch sae oil (i forgot the exact brand but its a famous one)

I cleaned the carbs last december and i have never seen this before. I have taken the cars out a few times already because of leaks etc. and this is the first time ive seen it.

The plugs are great. Either a touch brown or a touch white depending on how i adjust the idle screw.

The green thingy smells like gas aswell. Should i be worried
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Offline calj737

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Re: '74 CB550 idles fine then dies off later
« Reply #11 on: April 12, 2014, 06:42:22 PM »
If you believe it to be gas, then I'd not worry that your did something wrong. That bit of info leads me to believe your flooding the bike out which is why it's stalling.

Have you synch'ed the carbs and verified the correct float heights since you've rebuilt them? There's a few threads on here about a "Clear tube method" for confirming consistent float heights, and even homemade manometers for best result synching of the carbs.
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'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Jimsun

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Re: '74 CB550 idles fine then dies off later
« Reply #12 on: April 12, 2014, 07:25:45 PM »
Quote from: calj737 on April 12, 2014, 06:42:22 PM
If you believe it to be gas, then I'd not worry that your did something wrong. That bit of info leads me to believe your flooding the bike out which is why it's stalling.

Have you synch'ed the carbs and verified the correct float heights since you've rebuilt them? There's a few threads on here about a "Clear tube method" for confirming consistent float heights, and even homemade manometers for best result synching of the carbs.

Could it be flooding? I mean carb one is leaking gas atm. small drips.

Also, I have a 74 cb550, I have a drain bolt instead of the drain screw the next gen cb550 have.

I will remove them again and remeasure the float heights. From my initial assembly, they measured ~22mm. I will check again when the weather is good.
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Offline Killer Canary

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Re: '74 CB550 idles fine then dies off later
« Reply #13 on: April 12, 2014, 07:47:04 PM »
Maybe the green stuff is NOS. ;D ;D ;D  www.gixxer.com/forums/showthread.php?t=226570‎
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