1982 gs550 ignition problems...HELP!

[Defore]

OK so i have an 82 gs550 with 3000miles on her. Ive been working on bobbing it out for about 4 months she's finished except I can't seem to get it to run all the time. The coils are off a 07 virago and yet I still have the problem. OK so most the time ill get spark from all 4 plugs but sometimes its only from 1 and 4 but then sometimes theres no spark at all!? I can't figure out that's going on. I don't know if its the cdi or what? Plz help.

[BassCliff]

Hi,

These bikes don't have a true CDI but they do have an "igniter", which is basically an electronic points system. Yes, they can fail intermittently and they can be expensive to replace.

Make sure everything else is properly tested and physically sound, connections, wires, plug caps, etc.

Are the new coils 5 ohm?

See if these articles help at all...

Igniter/Signal Generator/Coil Test

Igniter Repair/Testing (2MB PDF)

Testing The Ignition System

Thank you for your indulgence,

BassCliff

[mike_of_bbg]

What's the primary impedance of the Virago coils?

Sorta smells like maybe an igniter going bad. Got to make sure that wiring is solid. Dyna S DS3-2 ignition is the solution for bad igniter or sig gen on your bike.

[Defore]

Well guys I tested the coils today with the bike off their reading from 3 to 3.5 ohms but when I turn it on and after I unplug the coils and test the wires going to the "ignitor" its not reading ohm but read 11.5 something volts. Now when I go to the ignitor, that black wire that should be grounded that comes out of the bundle of wires...well its carrying volt! So Im thinking a bad ignitor or maybe rectifier? It only does it sometimes on 1 and 4 but 2 and 3 almost never spark now and alway carry volts and not ohms. now lets say 1 and 4 are carrying volts, Ill turn it off then back on and itll be back to ohms? What the hell!!!

[mike_of_bbg]

Ohmmeter readings on the primaries should be taken with the coils unplugged and isolated. The coils get ~+12V all the time: the job of the ignition is to pull the ground when the spark is needed. When the ground is pulled, the magnetic field in the coil collapses and the voltage for the spark is induced in the secondary. After the spark, the ignition re-applies ground to build up the field again. The way I think this works with the factory ignition is that the ground is "switched" between the two coils. If you turn your motor over 180 degrees you may well find that the 2-3 coil is grounded instead of the 1-4 coil.

But to re-iterate the point: you should have +12V going to the coils all the time, on both coils, with the ignition on! You can test the orange/white wire against any solid ground for voltage. If your other coil does not have voltage it will NOT work. Testing the other wires (black or white) to ground will show voltage IF the coil is NOT being grounded. If the coil IS being grounded at that time (i.e., the field is being "built up"), then the voltage you will see between the ground wire and the battery ground should be close to 0, but you should measure close to +12V ACROSS the coil.

It may indeed be a bad igniter. It may just be my imagination, but it seems to me that the 550s in particular are prone to a hot-running charging system, which takes its toll on the transistorized igniters. The manual may say that 15.5V is OK charging, but it's not. ~14.8V should be your max. When you get your bike running again, you should triple-check the regulator output at ~5k RPM.

[Defore]

OK thank you. But now what do you think the deal is with the ignitor ground wire having 12 volts?

[mike_of_bbg]

Does it have 12 volts with the coil disconnected? If the coil is not being grounded by the igniter, then if you try to measure the potential of the coil (-) line to ground you will see ~12V because your voltmeter is completing the circuit. The VM has a high resistance (typically 10kOhms+). If you complete the circuit using the volt meter you have your coil and voltmeter as series resistances. So the voltmeter itself will be almost 100% of the potential drop and you're going to see near battery voltage.

OK thank you. But now what do you think the deal is with the ignitor ground wire having 12 volts?

[Defore]

OK so what do I need to do to test the ignitor?

[mike_of_bbg]

First test - swap the coil leads and check for spark (of course it will not run this way). If the problem stays on the same two cylinders, the issue is likely with the coil. If it switches to the other coil, then it's most likely the igniter.

You can try the test procedure here:

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A11

Look at the second one. If I get the chance I'll see if there's a procedure in the Clymer manual - I think there is.

[Defore]

I did that the other day and it does switch to the other plugs. But now I just went to check some stuff and no spark at all. It always jumps around, sometimes I get spark on both sometimes on just 1 coil and sometimes itll start up and run for a few secs then die. But when I do some how get it to run for a minute or so only 2 of the headers are hot and its getting gas so its pretty much all over the place.

[koolaid_kid]

OK so what do I need to do to test the ignitor?

BassCliff listed all the tests in his post above.