GS450 - Only one cylinder firing

[RJ138]

I am trying to get a recently aquired 1981 GS450T running. The bike was missing the starter solenoid and starter button, so I replaced them. I also bypassed the clutch switch. I then cleaned up the starter a bit and now the bike cranks over great.

However it does not run. I pulled the right plug (which looked brand new) and hit the start switch again and it started running. So now I know the right cylinder is not getting spark. I then took my multimeter and checked voltages and continuity between the O/W, W, and B/Y wires to the coils and they checked out okay (I think... I am new to electrical work.). I also swapped the wiring from the left coil to the right coil and then the right coil fired and the left one did not. So I guess that rules out the coil being bad.

Is there anything else I can check? I am thinking the little ignitor unit is not funtioning right. Could it be the pickup coil? Is the pick up coil the signal generator located under the Suzuki cap? Any tips on how I can check these?

Thanks in advance.

[tkent02]

Slow down a bit...
Is there no spark at the plug?
Have you replaced the plugs?
How are the plug caps?
Is everything else working properly?
Ignitors and pick up coils are expensive, troubleshoot first.

[RJ138]

Slow down a bit...
Is there no spark at the plug?
Have you replaced the plugs?
How are the plug caps?
Is everything else working properly?
Ignitors and pick up coils are expensive, troubleshoot first.

There is no spark at the plug. Both plugs work fine, I even swapped sides to check them. They checked out okay.

I swaped the wiring from the left coil to the right coil and the rightside spark plug fired. So I think the plugs, caps, and coils should be fine.

It appears everything checks out okay, except the igniter or signal generator. Not exactly sure how to test these. Unless I am missing something else?

[Nessism]

The signal generators are basically just a magnetic. The problem is most likely the ignitor. The service manual has a test so that, and checking the electrical plugs, would be a good place to start.

[RJ138]

The signal generators are basically just a magnetic. The problem is most likely the ignitor. The service manual has a test so that, and checking the electrical plugs, would be a good place to start.

I am a little thrown off by the Clymer manual. It shows a blue and green wire coming from the Signal Generator; mine has four wires, Green/White, Green/Yellow, Brown, and Black/White. The manual says to disconect the two signal generator wires, but I have four... I suppose I could just disconnect the plug going to the signal generator. I think the Green/Yellow must be for the oil sensor.

I tested the signal generator at the plug with my multimeter/ohmmeter and here are the results.
Brown - Black/White = 67.5 Ohms
Green/White - Black/White = 67.2 Ohms
Brown - Green/White = 134.6 Ohms

So it looks like that checks out okay since the Clymer manual says it should be between 60-80 ohms.

I guess the only thing left is the ignitor... I tried testing it with my multimeter and nothing happened, no spark on either cylinder. So the test must not be working, I will have to try it again later with a battery. It looks like the ignitor is the problem though. The plug looks good and the wires had good continuity.