Spark on one side only

[dezmoduo]

On a recently bought 90 GS500. It was running last weekend, and I topped off the tank and parked it. Today my son completed  the MSF and we wanted to take the GS out for a local ride.
 Some quick plug inspection shows spark absent from the left side. I swapped the plugs and the condition remained. I'll dig in deeper tomorrow, but I would like to hear any suggestions that might apply to this symptom.
I'm going to Ohm the coil, and perhaps swap it left for right.
I'm a decent wrench, long time rider, and new owner of a great little air cooled twin, which I think my sons gonna love. (once its running  hehe)

DEZ
NYC

[dgyver]

Had the same issue once and I traced it down to a corroded wire connection going from the ignitor to the coils. A little cleaning and added some electrical grease to prevent it from happening again. Treated all the connections in the wire harness too.

[dezmoduo]

So I'll pull the side panels off and if I'm not mistaken, the igniter is somewheres in there. I have a manual. I hope its something that easy.
Are you really a racer? Just curious. Watched donnington today. VEry soggy. But the 250's were awesome.
Thanks,

[dgyver]

It is on the left side. Black box about 4" square. If cleaning the connectors does not do anything then swap the coils. Doubtful that one went out. Possible that the plug wire from the coil is bad.

Not a racer but I am a legend in my own mind. I just like doing track days, more seat time anyway and a lot cheaper. At least the bike I just sold is racing again. Did not see the race but 2-strokes are a blast to ride.

The title under my name is a default for the post count.

[dezmoduo]

dgyver,
Thanks for the "racer" explanation. It all makes sense -- not . HA!!!

OK, Fired the bike this morning and it hit on all cylinders. WHoopee, so I go for a test ride. I pulled over to snug up the Tach cable and upon restart, I was down to a 250 again.

Rolled up my sleeves, (very hot in NYC), and dug in. Ohmed the coils, both read as spec'd. Checked for open wires from the left side cover connectors to the coils. None.

Oh yes, I cleaned and goobed all the connectors. They weren't too bad actually. The bike has 20K on it and seems to have been garaged pretty much.

NEXT: The  signal generator. I did the ohm check -- bwn to blk/blu -- and got the proper reading. (approx, analog meter). Did the grn/wht to blk/blu and NOTHING. I took the sig/gen cover off and checked integrity of my grn/wht from the generator to the connector on the other side. The wire is good.

I did an ohm test right there at the sig/gen on the two separate modules and one gave me the 200-400 K reading and the other gave me NOTHING.

SO, I think the sig/gen module for the left cylinder is bad.

Is there any aftermarket ignition stuff, like Boyer or Newtronics? This is a simple system which would lend itself to upgrade I would think.

Now I need to source the module or the whole plate.

What are your thoughts?

BTW, I'm putting my 76 GT 750A Buffalo back on the road. Its coming along well. Just redid the front brakes and beld them out. The engine should go in soon, if I can lasso my son long enough to assist.


DEZ
NYC

93 966 SS Duc
90 500 GS Suz
76 750 GT Suz

[dgyver]

I thought the signal pickup was just a magnetic sensor. Never messed with their construction since I have not had problems with it. I do not know of any other bikes that they can be used from.