No Spark on all 4 cylinders 1980 GS550L

[Guest]

first of all I would like to say that this site is very well managed and has been a wealth of knowledge over the past few weeks while I have tried to revive a 11980 GS550L. Yes, I am a schmuck that got suckered in to a low price for what seemed to be a good looking GS550 and somewhat easy bike to get running again. It has had some work done to it by a local bike shop but that was done years ago and the guy just didn't want to spend any more money on it so he decided to sell it cheap to get it out of his garage. it has: new carbs, one new coil, looks like a new ignitors and a new old stock CDI box. I based this on the visual of the materials definitely look newer than the other components around them among other obvious signs of replacement.

The bike doesn't have spark on any cylinders. I have checked:

1. ohms on the ignitors and they check out ok, they were the exactly the same on both leads. based on what I have read, that is normal.
2. checked the ohms on the coils. both primary coils were at 4 ohms and the secondary coil for cylinders 1 and 4 seemed normal based on research but the secondary coil for cylinders 2 and 3 gave a much lower, more than half, ohms reading
3. there is voltage at the orange / white wires going to the coils. there is steady voltage going to the white and black wires going to each coil as well.
4. there is voltage going to the CDI box on the two wires that should always have voltage on them. I am not 100% sure while I am typing but I think they are orange wire and black wire.
5. spark plugs are new
6. I have taken almost every connector I can see apart and made sure the wires were still connected strongly and they seem to be ok. the bike had been stored in a nice basement for a few years so it wasn't caked with dust and dirt. all the connections were clean and corrosion free.

what I am really scratching my head on is should i keep testing or is it time to start replacing parts? with the coil that seemed to check out bad, I am ok with replacing that, but should the other one spark even if the first is bad? I have no spark at all on any cylinder.

I don't know where to go from here. any help would be greatly appreciated. I think I have read almost every topic or post on this subject but I am at a loss for what it means that I have one coil that checks out with no spark and one coil that seems weak with no spark. if the coil that tested ok had spark, the choice would be simple, but I am afraid that if I replace the bad coil, I am still going to have the same issue of no spark among any cylinders. any help or advice would be greatly appreciated!

[tom203]

Ignition coils are very durable, so let's check them. Your primary ohms of about 4 is good. To check secondary, unscrew both plug caps from a coil, put your multimeter on 20k scale, and stick your meter probes into the plug wires (leading back to coil) - look for about 12 on meter scale,meaning 12000 ohms wire to wire.
measuring over plug caps is trickier due to corrosion issues in cap and connection - you might measure anywhere from about 20 to 40 kohms cap to cap.

550 ignitors seem prone to failure, buying ebay units might not be an improvement. Fortunately, a dyna ignition module is available for your bike- this replaces both those little signal coils and the ignitor.

[Brendan W]

You could disconnect the coils entirely and run two wires from the battery + and - to the coil. Then just break the return wire and see what kind of spark you get.
You have voltage at the orange/white coil supply. How much and what is the battery voltage? You also have voltage at the black and white return wires from the coil. Is this measured at the supply plug when disconnected ? How many volts are there ? These should be the primary winding earth wires. Having supply on them seems odd.
The black and white wires were afaik used on the points ignition machines but changed to black/yellow and a white wire for the later ignition systems.

[Jeremyrees05]

Thank you Tom! I like the way you think. Eliminate all the possibilities by removing all of the obstacles. The plug wires on this bike don't seem to have removable leads at the coil. They have a tight fitting rubber boot and no removable screw caps that i see. I can pull back the rubber boots and see the ign wires but they are glued or sealed to the coil. I am afraid of damaging them if I pull them out.

Going from plug cap to plug cap, I read 32.09k on coil for cylinders 1 and 4. I only read 2.2 ohms on the coil for cylinders 2 and 3. My meter is an automatic scaling meter so it switches between ranges automatically.

Based on this reading, I assume that the coil for cylinders 2 and 3 is bad. But should the bike still fire one coil even if the other one is bad? It might be wishful thinking instead of practical thinking.

[Jeremyrees05]

Thanks Brendan! I tested 12.6v on the battery. The orange/white wires have 12.6v on them. With the coils connected, both wires in each plug have the same voltage. Meaning 12.6v on the white/black wires as well as the orange wires. With the coil supply power wires disconnected, the white and black wires have less than one volt on them.

I tried to test the coils as you suggested and I get no spark on either coil. I connected a wire to the positive side of the battery and to the orange wire of the coil packs. I then connected another wire to the battery and touched/removed the second wire to the black wire and didn't see any spark. I tried the white wire and got the same results, no spark.

I have checked continuity between the coil mounting bolts (I believe them to be a ground for the coils but not sure) and the engine block and it checks out ok.

Still has my head scratching. I think the coils should have sparked for that test but they didn't. Thanks again!

[tom203]

image.jpgUnless the caps were superglued on, they will twist off with force. They are screwed on- see pic.
These ignition coils use the wasted spark scheme- one coil fires the two spark plugs simultaneously. If you're checking for spark on #1 ,then #4 needs to be grounded in order for spark at #1 to make circuit.

[Jeremyrees05]

Thank you for the info Tom! I did not have the other plugs grounded. I was only working with cylinders 3 and 4 hoping to see spark but from previous testing, cylinders 1 and 2 were off as well. I will re check coils.

Also, I misunderstood you from previous post reply. I thought you meant to take off the wires from the coil end, not the plug end. I will try to remove the plug caps and re test for ohms.

thanks again!

[Jeremyrees05]

I reconnected the spark plugs for cylinders 1 and 2 and tried triggering spark with jumpers again. still no luck. I had a wire from the battery on the orange wire and then another wire touching and removing it from the black wire on coil pack 2 then the white wire for coil pack 1. still no spark. maybe I did it wrong?

[Jeremyrees05]

I rechecked the ohms for coil 1 without plug caps and it was 15k. there is one problem! previous readings were 2 ohms.

coil 2 read 14.64k ohms. the wire for #3 cylinder was green with gunk. is it ok to cut back and reconnect the wires?

thanks again for all your help!

[Jeremyrees05]

Brendan, I re read your post and I was connecting the wires wrong to check the coils. I just checked them again, and I have spark on cylinders 3 and 4! I will proceed to check cylinders 1 and 2 but I am guessing that I have spark there to. #4 was stronger than #3 though.

thanks again!!!

[Brendan W]

I rechecked the ohms for coil 1 without plug caps and it was 15k. there is one problem! previous readings were 2 ohms.

coil 2 read 14.64k ohms. the wire for #3 cylinder was green with gunk. is it ok to cut back and reconnect the wires?

thanks again for all your help!

Not only is it Ok it obligatory.

[bobgroger]

Brendan, I re read your post and I was connecting the wires wrong to check the coils. I just checked them again, and I have spark on cylinders 3 and 4! I will proceed to check cylinders 1 and 2 but I am guessing that I have spark there to. #4 was stronger than #3 though.

thanks again!!!

Let's be sure you have the plug wires connected correctly. One coil's leads go to 1 and 4. The other coil goes to 2 and 3. Since the wires are all about the same length it is easy to get them confused. Also the #1 and 4 leads have a cap that is a bit shorter than 2 and 3.

[Jeremyrees05]

Thank you bobgroger!! Good reminder for reassembly! The wires are numbered on this bike so it has been easy to take them off the plugs and reinstall without getting them mixed up. the caps were not numbered but they were easy to put back together. I went ahead and trimmed back all 4 wires about 1/2" to get to a "fresh" looking part of the wire.

thanks again!

[Jeremyrees05]

I checked cylinders one and two with the jumper wires and they both have spark. The coils both have spark when using jumper wires. So, that means plugs are good (which they should cause they are new) and coils both have spark.

Next step? I have researched information on how to check ohms on the igniters and they seem to be ok. 65.2 on the black and green white wire and 65.7 ohms from the black and brown wires. Is that ok?

Thanks again for your help!

[Jeremyrees05]

I checked ohms on all the connectors tonight and I found a few that were not connecting very well. I cleaned them and greased them with dielectric silicone and after cleaning, they checked out ok. I checked the coil connections, cdi connections and also the ignitor sensor connection. after cleaning and greasing, they checked out ok but still no spark?

any ideas on what to check next? any help?

thank you in advance. I really appreciate all the help I have received thus far.