Ignition Troubleshooting

I have what I believe is an ignition problem on my G15CS that has me totally perplexed. I'm hoping someone can help me identify the problem. It has a simple Lucas two-coil, two-points & condensers system with a capacitor. I ride the bike regularly and it always starts on the first or second kick. After my last ride, I washed it down to get the road grime off and when I tried to start it a few days later, it wouldn't start. I assumed something got wet so I dried and cleaned out the distributor and ran a file over the points. It still wouldn't start so I started to check wiring & components. I found no spark on one cylinder and what appeared to be a couple grounded wires. I ran bypass wiring and again ran checks. Everything seems to be correct now, no grounds, points circuits open and close correctly, have spark on both cylinders, battery charged up. Now after a lot of kicking, I can sometimes get it to fire and it will rev up cleanly and then promptly die. It seems like it is either running out of spark or fuel. I have checked to verify that there is fuel getting to the carbs ok. Carbs are new Amal Concentrics.

What could cause this symptom? Could it be the capacitor, coils or something else? Points and condensers were changed a year ago.

jgmotto said:

After my last ride, I washed it down to get the road grime off and when I tried to start it a few days later, it wouldn't start.

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Maybe some water from the wash-down got into the carb float bowls?

Drain them?

Just went out and drained them. Even though I drained the bottom of the tank, I forgot that the water could settle in the bowls. Kicked it a couple times and it fired up and I revved it twice but unfortunately, it just died again and I couldn't get it to fire anymore. I drained the bowls a second time and kicked and kicked but it wouldn't fire again. I suppose I could drain the tank and refill with fresh fuel to eliminate that from the equation before I start replacing ignition components.

After you freshen up the fuel, make sure you are still getting spark by laying a plug against the head (both of them). Report back.

Slick

Sometimes it is possible for plugs to fail. I had it happen recently when the motor coughed once then died after the bike had been standing for months. It absolutely refused to start. Two new plugs and it fired up and was brand new again. I suspect it has to do with the carbon on the plugs being affected either by fuel or moisture on the first kick.

Last night, I pulled the plugs and they were definitely wet with fuel.
Replaced with new and got a good strong spark but not always.
Put voltmeter on the coil primary and voltage not consistent.
When voltage read good, I was able to start and run it but after about 30 seconds the voltage nosedived and the motor quit. Did this several times.
Disconnected the capacitor and had no effect.
Ammeter is bypassed. Have had a bad ammeter cause similar problems in the past.
When running, the voltage came up OK so it appears to be charging OK. Intermittent fault in the alternator circuit could cause it. I suppose I could disconnect it and try to run off the battery.
Next time I get a chance, I will trace the wiring between the battery and the coil primary. Could be a bad ignition switch or the wiring feeding it.
Could a failing coil produce these symptoms also? Is there anyway to check the coils?
Any other suggestions would be appreciated!

Well, after spending the last couple of weekends chasing this problem, I finally isolated it to an intermittent fault in the ignition switch. Now it starts first kick just like usual and runs smooth. Goes to show, always check and double check the simple things first!