Topic: 79 CB650 cylinders 2&3. Need help

[Scotiabiker79]

Hey all
So I’ve had the 650 running well since I started it up after the winter
Had one ride on her last week
Started it today and it was only running on cylinder 1 & 4
I pulled plugs and put new ones.  Same.
I pulled the plug caps off and it would only run on 1 & 4
Put plug caps on and won’t start at all
The plugs on 2 & 3 were getting fuel

It was running perfect before today. 

Any help is appreciated
Thanks
Darren

[rluser]

Swap positions on spark units?  Coils?

[Tracksnblades1]

Do you know how to check if 2&3 are firing at the spark plugs.?

[Scotiabiker79]

I boosted the battery and she fired on all 4 cylinders.  I didn’t think a low battery would cause it not to fire on all 4.  I know at idle when running it does not charge battery. 
Strange
Tracks: I tried to start it before with the #1 and 4 spark plug caps off if that’s what you meant.  It wouldn’t start
Hopefully it was just the low battery causing issue

[Tracksnblades1]

I boosted the battery and she fired on all 4 cylinders.  I didn’t think a low battery would cause it not to fire on all 4.  I know at idle when running it does not charge battery. 
Strange
Tracks: I tried to start it before with the #1 and 4 spark plug caps off if that’s what you meant.  It wouldn’t start
Hopefully it was just the low battery causing issue

Good to hear it’s running on all four.

I have an old 76f that will fire one coil down below 6volts but not the other coil..🤪

Keep her charged up..😇

[bryanj]

The 650 has brushes and slip rings on the rotor which have always been an issue and not charging at idle is common plus electronics likes full voltage to work, more surprising 1&4 worked than 2&3 didnt

[fizzlebottom]

... more surprising 1&4 worked than 2&3 didnt

In this instance it would have been nice to see if swapping component positions up the whole ignition chain would have made a difference.