2 cylinders not firing

when I first rode the bike (81 650 CSR) I didn't check to see if I was getting spark on all the plugs. I road it to the gas station and it felt really weak, after I filled it up she pulled like crazy so I assumed that I had a fuel delivery problem or that my reserve circuit had a clog in it.

Now I find that two of my cylinders aren't firing and it's giving me the same symptoms as when I thought I had a fuel problem.

My thoughts are that the plugs are firing sometimes and not others. I know the coil is fine so am I looking for a bad connection? Maybe the ignition module is bad? What do you think? Any and every idea would be helpful.

Which cylinders? 1&3 fire together and 2&4 fire together. If 1&3 don't fire, look at coil or wiring immediately associated with that coil. Same with 2&4. If it is a 1&4 type issue look to plug wires or plugs thenselves.

No, it's 1&4 fire together and 2&3 together.

Again if it's the 1&4 or 2&3 combos that don't fire, it's probablly a coil or coil wiring issue.

Rob is right 1&4 are on the same coil as are 2&3.
You have'nt said which two cylinders are not firing properly.

Has the bike been sitting for any length of time? I had firing problems last year when I started up after the winter. It turned out to be a blocked jet in the #2 carb. I dont have a fuel line filter on mine and got some silt from the tank into the carb.

Post edited by: rede4u, at: 2006/03/07 19:35

I was firing on two cylinders just last week on my 550.
If you let it idle for a while, does it surge?

Have you tried replacing the clip connectors to the coils? That has worked for me in the past. After time they become loose and open slightly, thus arching and causing the cylinders to fire only when it "makes contact". might not be the same prob, but sounds like it.

Wow 3rd time I used that diagnosis today :blink:

I hope I know more about these bikes than just the coils :lol:

Hope that helps

It was 1&4 that weren't firing. I just got back from tracing the wires back. The bike had been sitting for quite some time and it was given to me for free in exchange for helping to get 3 78 650 SRs going.

The main problem I've been having is that the battery exploded. This turned out to be related. I missed replacing one wire which just so happened to be the power lead for the coil for cylinders 1&4.

Now I just have to strip the bike down to repaint the frame, then the rest of the bike... it can wait.

Thanks everyone for your fast replies. I'm about to post something about turn signals. I hope it's entertaining for us all.

storysunfolding wrote:

It was 1&4 that weren't firing. I just got back from tracing the wires back. The bike had been sitting for quite some time and it was given to me for free in exchange for helping to get 3 78 650 SRs going.

The main problem I've been having is that the battery exploded. This turned out to be related. I missed replacing one wire which just so happened to be the power lead for the coil for cylinders 1&4.

Now I just have to strip the bike down to repaint the frame, then the rest of the bike... it can wait.

Thanks everyone for your fast replies. I'm about to post something about turn signals. I hope it's entertaining for us all.

Oh great, I hope it not a photo of a midget sitting backwards on your bike with his hands out to the left or right flicking flashlights. :whistle: :whistle:

Post edited by: ran429, at: 2006/03/13 03:48