CB550 coils

[Green1]

Does the 550 share the same coils as the 400&750? Only asking as the 550 has developed a massive flat spot right up to 3500rpm and was hunting at tick over today when ridding in the rain.
I have a spare set of pattern coils I could try so it would be rude not to try them.

[Johnwebley]

Does the 550 share the same coils as the 400&750? Only asking as the 550 has developed a massive flat spot right up to 3500rpm and was hunting at tick over today when ridding in the rain.
I have a spare set of pattern coils I could try so it would be rude not to try them.

 I am pretty sure the coils are the 703 type,same as the 500,
but your symptoms sound more than just coils

[mike the bike]

Are they the originals?  The reason I asked, the originals ain't rain proof.  That's why I bought Dyna coils - saves me waiting around for the RAC when there's a monsoon.

[Green1]

My original 750 coils were rain proof I only swapped them when I ran out of HT lead to trim and that developed a low down flat spot.

John don't say that that's not what I want to here. It had issues before and had James scratching his head for awhile. 
But It did run well when I picked it up about 7 months ago.
Today was the first ride in heavy rain.

[JamesH]

Mick - can't recall now but did I fit a boyer bransden kit to the 550? If it's something I did / didn't do right, make sure you drop me a pm and we'll work it out. I've still got to get that bloody clock cover / fender stay up to you come to think of it...

[Green1]

Don't panic James I'm not blaming you but the bits and bobs you owe me would be nice 

Yes it does have the boyer ignition

[deltarider]

Many start by suspecting the coils and although they can fail, this is seldom the case. Both CB500 and CB550 are vulnerable in wet conditions. Carefully inspect and clean the HTleads and check for possible arcing between the HTleads/plugcaps and the head. Best seen in the dark. Some spray a mist of water to detect it. By listening closeby you may hear the cracks. How old are the plugcaps? What do they measure? Are sparkplugs gapped correctly and not too wide? Did water(mist) get behind the ignition cover?

[mike the bike]

On mine the rain was getting in between the HT leads and the coil.  Tried sealing them but it didn't last

[Johnwebley]

On mine the rain was getting in between the HT leads and the coil.  Tried sealing them but it didn't last

 on mine the HT outer fractured completly next to the coils,

 I was to lazy to try the repair,so bought a couple of Dss finest !!!!
with Boyer ignition they give a massive spark

[Green1]

I don't actually suspect the coils most likely the HT leads as they are pulled very tight on the caps.
I did manage to get a look at it today and there was a little moisture behind the point cover so if I'm lucky it might just be that.
I looked into why the throttle is heavy as well and one of the cables has a twist in it and the other is as stiff as hell so that should be an easy fix with a couple of new cables.
 
Are the cable supposed to be tied to the frame above or below the coils? Mine are just floating around at the moment

[Green1]

I sealed up the points cover and re crimped a loose connection to the boyer today and now there is just a small flat spot at about 3500rpm. So I'm getting there. Still got to check for arcing plugs and caps are all new so they should be good. 

I also looked at a job in Leiston  today so popped in at DSS and have been told Honda have discontinued the push cable. So it looks like I will have to use pattern cables.
I'm just running it with the one new pull cable at the moment and it has improved the throttle no end.
 

[Green1]

Just run the bike in the garage as its nice and dark out there and there's no arcing from the Coils or leads wet or dry.
So I guess that's good 

[Green1]

Just noticed a little bit of staining around the cast carb inlet manifold on the engine side
Would an air leak hear cause my flat spot?

[hairygit]

Certainly a possibility!

[mike the bike]

Deffo.  My 550K3 didn't have power above 4000 unless I pulled the choke out a bit.  Changing the inlet rubbers transformed it.