Topic: CB550 Only running on two cylinders, bad coils, plugs, boots? Photos and Video

[NoLuck]

Hi all.
I'll be as brief as i can.

1975 CB550 K. Only upgrades are Dyna S and a Mac 4-1 Exhaust.

PROBLEM:
Only running on #1 and #4 cylinders 
2 and 3 are cold.
Spark plug tested and only getting spark to cylinders 1 and 4
No spark to 2 and 3

Would this be caused by bad coils? Any other problems that would cause this?
I will be posting video and photos of all tests i do for this bike.

Looking forward to all of your helpful suggestions.
Thank you

[NoLuck]

Video of trying to start up

[DH]

Dyna S have given many problems to many sohc4 owners. Do a forum search using dyna s as the keywords. The dyna unit is what turns the ignition coils on and off to fire the plugs. cyls 1/4 fire together, and 2/3 fire together. What you describe is similar to the problems others have had.

edit....try swapping wiring from the firing coil to the non firing coil and see if the no spark problem moves to the other two cyls.

[NoLuck]

How do I swap plug wires like you said? I would love to try this

[DH]

How do I swap plug wires like you said? I would love to try this

just as a test for spark, remove 2/3 plug wires, conect a plug and lay it on the side of engine. cross wire the yellow wire qnd the blue wire, the ones in your pic, and see if the 2/3 coil will produce a spark. Do not try to start it wired like this

[NoLuck]

Ok I'll try that but when u say do not try to start what does that mean don't I have to have the key on and the killswitch set to run in order to try and test for a spark?

[DH]

Ok I'll try that but when u say do not try to start what does that mean don't I have to have the key on and the killswitch set to run in order to try and test for a spark?

yeah, just keep in mind that when wired this way, its obviously only for test purposes to see if the no spark problem moves to the other coil. If that occurs, the dyna s may have failed, and you may need to replace it before you can accurately troubleshoot any farther.
And there could be other problems, troubleshoot one area at a time thoroughly before moving on.

[Hondawggie]

Hi all.
I'll be as brief as i can.

1975 CB550 K. Only upgrades are Dyna S and a Mac 4-1 Exhaust.

PROBLEM:
Only running on #1 and #4 cylinders 
2 and 3 are cold.
Spark plug tested and only getting spark to cylinders 1 and 4
No spark to 2 and 3

Would this be caused by bad coils? Any other problems that would cause this?
I will be posting video and photos of all tests i do for this bike.

Looking forward to all of your helpful suggestions.
Thank you

Glad I saw your post.  Was thinking about moving away from points on my '76 CB550F.  Not any more.  Pretty bizarre Dyna would have this rep -- it's a go-to brand for a lot of riders.

[DaveBarbier]

Noluck, you should post your test results I had you do for coils, plug caps and such here. Or just link to the thread.

This is one issue for having multiple threads on the same topic, sometimes people won't get the full story

[NoLuck]

Here is a link to the original post i started. Full story there with pictures as well.
http://forums.sohc4.net/index.php/topic,158041.msg1811974.html#msg1811974