Topic: Running on 3 cylinders at idle.

[Calumjs]

My cb550 is only running on 1,2 and 4 at idle, I pulled the 3 cylinder plug and it's got nice spark but is dry as dead dogs donga. It runs on 4 when it's revving high , but when I'm in the low rev range it's hesitates a bit then pulls very well. I'm guessing carb 3 has issues, any idea what I need to look at? It's not ignition as it has dyna coils and electronic ignition and it has a great spark just no fuel at idle/low revs!

Any help will be great!


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[harisuluv]

You all have all the symptoms of a clogged idle jet.

[Vinhead1957]

You all have all the symptoms of a clogged idle jet.

+1 on the clogged carb

Clean and run some seafoam when you fill up

[Deltarider]

What model 550 is it? Keihin carbs? PD?

[Calumjs]

Thanks guys, can I access the idle jet from removing the bowl while the carbs are still on the bike?


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[Calumjs]

It's a 74,


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[Deltarider]

Sure, it's easy. Remove the float bowls and use a small screwdriver to remove the slow jets. No need to remove the carbs. I can do it with my eyes closed. In order to get at #3 you have to remove the #4 bowl too. While you have them opened you might as well inspect the mainjet (o-ring) and the needle jets aka emulsion tubes. http://forums.sohc4.net/index.php?topic=138165.msg1560006#msg1560006

[Calumjs]

Great! Thanks for the info! One last issue is that my idle is rather high even with the idle adjuster screw screwed all the way out so it's not even making contact with the bar. Is there a way of adjusting the idle other then that one adjuster screw on the right side of the bike? Thanks again


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[goldarrow]

Yes. Do carbs synch to bring idle down

[harisuluv]

Great! Thanks for the info! One last issue is that my idle is rather high even with the idle adjuster screw screwed all the way out so it's not even making contact with the bar. Is there a way of adjusting the idle other then that one adjuster screw on the right side of the bike? Thanks again


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If you synced your carbs they were done so without being synced relative to the adjuster screw.  That is why you have no range of adjustment.  When the screw is in contact and you have a range of contact in and out, that is where they need to be synced at the same height.

[Calumjs]

Okay so I want to sync with the adjuster screw at half way? So I can adjust 50% either way?


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[harisuluv]

From the point where the idle adjust makes contact to where it bottoms out.  That is the theoretical adjustment range possible for the idle adjust screw.  That is where they have to be synced not only to each other, but the correct height ie. drill bit or whatever you're using to to bench sync.