#3 & 4 cylinders not firing

[tudawg7]

I have a problem..... I've searched around on the forum but don't see anything like it .....my two right cylinders which I believe are the 3 & 4 cylinders are cold to the touch when the bike is running....I understand from what I've read on here the one coil controls 1 & 4 and the other one controls 2 & 3 .....is this correct.....and if so does anyone have any idea why my 3 & 4 would not be firing......could I have both coils gone ???
Thanks

[tkent02]

Not a coil issue, or it would be 1&4, or 2&3.

Start troubleshooting fuel, spark, and compression, it needs all three...

[seuadr]

http://www.thegsresources.com/_forum/showthread.php?t=124580

try some of these things.

[cmart45]

2 and 3 cylinders not firing

If you have spark at the plugs when grounded on head then it is another issue. Check and clean all connections.If not,electrical. Dirty carbs.Check your compression to see what condition it's in.Swap coils left side to right to test coils. Ignitor test(1 1/2 volt AA bat connected to green- and blue+ on ignitor side of connector wires with ignition on. Connector unpluged and plugs 2 and 3 grounded to head. Touch +side of batt to blue and - to green using jump clip wires. Number 4 spark plug should fire when connected and number 3 should fire when disconnected.
Dirty carbs,trace all passages and clean all traces of gunk and trash.
Check for good fuel flow out of pet cock to carbs.
Spark generator test! ohmmeter to same blue and green wires but on spark generator side of connection. 250 to 360 ohm reading should be within specs if not change generator.
Good luck!

[seuadr]

i'm in the same boat as you, i have, i believe narrowed everything down to ajusting the valves and/or testing the timing. as said before, if it's a single cylinder from each coil, it's 99% not electrical.

[Mercaholic]

Plug boots

If no spark, try removing and reinstalling plug boots. Better still, just replace all four for less than $30.

In cold conditions, the originals will provide marginal continuity.

Let us know what you find!

[thezmann76]

If you have spark at the plugs when grounded on head then it is another issue. Check and clean all connections.If not,electrical. Dirty carbs.Check your compression to see what condition it's in.Swap coils left side to right to test coils. Ignitor test(1 1/2 volt AA bat connected to green- and blue+ on ignitor side of connector wires with ignition on. Connector unpluged and plugs 2 and 3 grounded to head. Touch +side of batt to blue and - to green using jump clip wires. Number 4 spark plug should fire when connected and number 3 should fire when disconnected.
Dirty carbs,trace all passages and clean all traces of gunk and trash.
Check for good fuel flow out of pet cock to carbs.
Spark generator test! ohmmeter to same blue and green wires but on spark generator side of connection. 250 to 360 ohm reading should be within specs if not change generator.
Good luck!

I have a question, my 82 Gs1100e has a weak spark at all 4 plugs. The signal generator has an ohm reading of 120 which isn't really high or really low. would that indicate a bad generator? I also did the test for the ignitor and received only a faint spark on #4 plug once but could not replicate. Would it be possible that both of those items are bad? The bike ran fine when parked (in 1990) and only has 2,214 miles on it. Could these parts go bad from sitting? Thank you for any help you can give.

[Big T]

I have a question, my 82 Gs1100e has a weak spark at all 4 plugs. The signal generator has an ohm reading of 120 which isn't really high or really low. would that indicate a bad generator? I also did the test for the ignitor and received only a faint spark on #4 plug once but could not replicate. Would it be possible that both of those items are bad? The bike ran fine when parked (in 1990) and only has 2,214 miles on it. Could these parts go bad from sitting? Thank you for any help you can give.

Yours could be:

1. Igniter
2. Connections to coils. Is there 12V at the coils?
3. Plug boots.

If it ran fine in 1990, that's 18 years of corrosion. Yes, they go bad from age and it doesn't matter if you're riding or sitting

[thezmann76]

Thank you, I'm going to replace the coils and the igniter and see if that does it. If for some reason it doesn't, it's back to the drawing board!!

[ryonker]

When I bought my 79 GS 750 cylinders 2 & 3 were not firing. I had spark and later I found out both coils were fine. After taking apart the carbs, I discovered the problem; whoever had take out the carbs before had put the floats in carbs 2 & 3 upside down (oops) so cylinders 2 & 3 were not getting gas. The bowls were totally dry. Flipped em around and away I go!!!!