Coil test

[Thomas Kenny]

1984 GS550ES

A couple of weeks ago, my bike began struggling to run and now will not start. I've got fuel but not a real strong spark. I checked my signal generator pulse pickups and the book calls for 250-500 ohms. They each read almost 400 ohms so I should be OK. I just did an igniter test and I am getting spark but not a strong spark. I tested my coils. They are marked 12v 3. I am assuming that the three is for 3 ohms. I tested both coils on my ohmmeter and am getting a reading of 2.3 ohms.

Should I be getting a strong 3? Do I need to replace my coils? Where is a good place to get some replacement coils and high tension leads if I need to replace them?

Any help appreciated. Ta Ta, Tom

[Jethro]

Check the voltage that is going to the coils with the ignition on but the bike not running. If you have less than 11 volts going into the coils that may casue a weak spark. Often times people replace coils, but it's the crazy wireing that Suzuki engineered that is to blame. The power feed for the coils goes from the battery, to the ignition, back to the fuse box, to the headlight bucket, to the right bar switch, back into the harness and out to the coils. Many folks install a relay with power coming directly from the battery.

[Thomas Kenny]

Thanks Jethro, I check it tomorrow :-D

[Thomas Kenny]

Ok, I couldn't wait Jethro, I measured the current and the right coil is a solid 12 volts and the left is approximately 11.2. I need to get a digital volt/ohmmeter :-D So real slooowwww, how do I set up a relay between the battery and the coils. Will this keep the coils hot with ignition switch off? I am not afraid to play with electrical, but being technically stupid, on the sparky stuff I don't want to fry myself or the bike. So I've got two leads to each coil from the harness and?

Your insight is welcome.........

[Jethro]

11.2 volts will not casue the coils to have weak spark. Your problem is either with the coils or something else.

[Thomas Kenny]

Thanks, I am thinking perhaps the coils or high tension leads are breaking down after 22 years, so I am going to look for replacement coils and leads as everything else seems to be working.

[DaShadow]

have you thought about a tune up?¿?
new plugs may be the way out of this jam...

[Thomas Kenny]

Thanks DaShadow, I just put new Irridium plugs in the bike and they read good. My bike has done this a couple of times before for no good reason after running like a champ, and number four has been intermittent when warming up. After testing the spark at the plugs several time # four sometimes does not fire. When I wiggle the connections to the coil that fires number 4 and give the coil a good whack :-D It will spark and then quit again. I took of the high tension cap from the lead and cut about 1/8 inch off of the lead and screwed the cap back in but it still is an on an off thing. So I think I will look at buying new coils and leads since everything else checks out ok. Just need to find coils and leads that aren't gold plated :-D