Two Dead cyclinders. Again.

[Hummer]

I think I'm missing something here and hope that it sounds familiar to someone who has resolved a similar issue.

I just upgraded my whole ignition system to the Dyna, thinking it would resolve an issue that has plagued me. I originally thought I had a carb problem due to a heavy fuel smell that went so far as heavy vapour in the exhaust. It dawned on me in the spring that it could be a coil problem when I stumbled on the fact that one of the header pipes was actually cool to the touch - I traced and tested and found that two cylinders weren't firing, both shared the same coil, and considering the age of the bike, a brand new Dyna seemed like a good choice. It ran just fine for about a week and I gave the bike back to my dad to enjoy for the summer.

The bike wouldn't start for him shortly afterwards, so I checked connections and traced the problem back to the fusebox. There was a bad connection that was to blame; tough to find since it moved just enough to test fine at a standstill but with any movement all electrical on the bike would shut down. I cleaned up the connections, reconnected it and the bike started.

And now we're back to the original problem. Cylinders 2 and 3 aren't firing. I've been thinking about this and this has been the problem with the bike from day 1. When I bought it some 5 years ago and before I knew anything about working on it, I had a local shop give it the once over. The mechanic had the same issues and tracked down a used ignitor for me. This is obviously something that continues to surface but why? I had that bike down to frame and engine, cleaned all the connections on the harness, have now replaced the ignition...what am I missing? I'd love to get it running for the last month or two we have of good weather but I'm also tempted to drive it into a field and set it on fire.

A break in the harness somewhere? Bad ground? Haunted ignition? Maybe I need to build my own harness over the winter? If anyone has fixed a similar problem, I'm all ears!

[Nessism]

How is the coil voltage? Adjusted the valves lately?

The ignition circuit wiring is very simple. I'd check every connector in the circuit and consider removing the terminals from the plastic connector shells and cleaning them and pinching the females closed for good contact. Problem could still be the ignitor, but it won't hurt to verify the wiring first.

[Hummer]

Voltage was good when I installed the new ignition - the Dyna replaced the stock setup so no ignitor needed. I had the whole harness off the bike last summer for the rebuild and cleaned every contact point, making sure there was a solid connection when I put it back together. The only thing I can think of in that regard is that a wire was pinched and/or broken somewhere.

[Hummer]

I also picked up a new fusebox the other day to changeover to the blade-type fuses instead of glass - figured since that was one place I knew was an issue within the last year, I could start there.

[Seana23]

Hi babes.
Is your battery charging ok...
Ive been chasing a weak spark on 1+4...
Ive cleaned carbs many many times but realised that with all the testing i was doing, the battery was a wee bit run down, so once charged, the bike went like stink!!!
See if it resolves with a fully charged battery..
Good luck.
Xxx

[BigD_83]

I just upgraded my whole ignition system to the Dyna, thinking it would resolve an issue that has plagued me.

I just want to confirm something with you before moving on:

Your ignition upgrade was the Dyna S AND coils?

EDIT- I went back and reviewed one of your older threads, and your dead cylinders were 1 & 4 back then... what is the same/different since that time? Are you still using the same set of spark plug wires?

[Hummer]

Battery was brand new last season and stays on a maintainer when it's parked.

I did replace the whole ignition - coils and all. And although I have only been able to fit in a few hours a week for anything other than work, I confirmed that I'm not crazy tonight by taking things apart and checking all the connections.

There's nothing complicated about this setup! So what's wrong!?! Laid the plugs on the block and turned it over - sparks on 1 and 4 but not 2 and 3 . One odd note - turning the key on or off gives me a spark on 1/4. That shouldn't happen should it?

Ignition is straightforward - all connections are good and resistance is in spec. Tested the coils at primary and secondary - check.

I left things apart tonight to think on it overnight and see what makes sense. If the coils are good, and all connections are secure, where's the problem? I'm second guessing everything now...but really, there are about 4 wires that makeup the whole ignition and they tested just fine. Maybe a broken wire somewhere? Bad ground when it's all back together?

[tom203]

Hummer said...

"....turning the key on or off gives me a spark on 1/4. That shouldn't happen should it?"

No, apparently coil 1/4 is being grounded all the time somewhere (either ignitor or wiring problem) - turning key off/on breaks the positive connection so then you get spark. If you're sure about wiring, inform dyna.

[Hummer]

Well tonight I took everything apart - traced wiring from the headlight back to double check grounds and any other connections. Put things back together and I get a spark on all four plugs - must have been a poor connection somewhere.

I'm still getting the spark when I turn the key off or hit the kill switch. A quick search told me that at least a few ignition manufacturers advise that this isn't a bad thing and should actually be expected - thoughts?

Regardless of spark or not, now the bike won't start at all. I'm suspicious of a bad connection in the fuse box again - there were at least a few times when I was cycling the starter that pushing start did absolutely nothing. I like the looks of the factory fuse box (strangely enough) so maybe I'll give cleaning it one more try. I've got a new fusebox with blade style fuses if that fails.

Bed time for now - work in a few short hours and then back to my lifetime sentence of fixing the GS.

[koolaid_kid]

The spark at engine turn off is normal and nothing to worry about.
There are only three things your engine needs to run: Spark, fuel and air.
If it is turning over and getting spark, you need to look to the fuel issue. Did you set your petcock to PRI for a few moments to fill the fuel bowls?

[mike10]

swiched wires maybe

Could the plugs be getting spark but not at the right time. Out of sinc, somehow. Like swiched wires on the coils, sig generator pick ups not right just a guess but it seems like everything is there just not at the right time

[koolaid_kid]

Could the plugs be getting spark but not at the right time. Out of sinc, somehow. Like swiched wires on the coils, sig generator pick ups not right just a guess but it seems like everything is there just not at the right time

Good suggestion, mike. You can check this using an inductive timing light, btw.

[Hummer]

The frustrating thing is that I had the bike running a month ago when the new ignition went in - timed it with the light and everything. She ran better than ever. And then for no apparent reason, just wouldn't start up one day.

I turned her over a few times this morning again - the start button did nothing the first time, but putting pressure on the fuse box got her to turn over. I'll focus my attention there next - at the very least I've got a poor connection. Unfortunately any new repairs will have to wait until after the weekend.

Thanks for the ideas so far guys - I'll post any updates.

[Roadkill2]

I seem to have the same problem as you :-( Wiring and oils all test fine. But not firing on 3 & 4. Stock ignition and coils. Gonna put new plug leads in a spare set of coils..

Funny thing is, it ran fine this morning. I am using a car battery to swing the motor, so no "Battery issues". I am lost and admit defeat for today. Took the ignitor off, and gonna clean it tonight.

Possibly braai and drink the problem away briefly. :-)

[Nessism]

What about the valves? How is the compression?

That wasted spark business is a characteristic of the Dyna S.