80 GL1100 no spark at 3&4

[gripitnripit]

Hey all,

New 1980 GL1100 owner and new to the site. I’ve been searching high and low on this site for awhile as a guest and have exhausted my efforts to figure this issue out. I got the bike last year and have been working my way through all the issues the ol’ “it ran last time I rode it, might need carbs cleaned” scenario. I found a head gasket leak in my rebuild process and have since gotten to the point of restarting the bike after replacing head gaskets. NO SPARK ON 3&4

I knew they were firing prior to rebuild as the steaming of the plugs was moving between all cylinders which tipped me off to the head gaskets in the first place.

Battery: 2017 year code, took it to advance and they tested it. Charge was depleted slightly as I just turned it over a couple times before taking it. 328/340max CCA and 12.3 VDC when tested. Seems fine...

COILS:
both housings are cracked BUT 2.4 ohm primary and 22k ohm secondary each. I can get spark to move by taking the yellow wire from right coil + (1&2) and connecting where blue wire on left coil + (3&4) should be

On to the spark units:
Brand new, and work in any variation of above scenarios so I know they are both sending spark EXCEPT when hooked into the connector that has the blue wire for left coil

Which leads me to believe blue wire has issue. 0.2 ohm back to the pulse generator so I believe the wiring is fine

Pulse generator tests:
Blue/white resistance 540 ohms, 0.3 VAC when cranking
Yellow/white 570 ohms, 0.4 VAC when cranking

Everything seems to be testing ok which really has me scratching my head. I’m thinking:
1. Battery is kinda old but trickle charged fully over night, still no spark 3&4
2. Coils are cracked but sparking, 2.4 ohms is off of the motorcycle but 3 ohms through the wiring
3. Pulse generator AC voltage test is running high. I read an old post when a Honda tech said in school he learned it should be 0.1-0.2 VAC range

Don’t wanna throw money at it and I am really dragging my feet having to dig out those pulse generators

Sorry for the long post and thanks in advance for any help guys!!

[Rambozo]

By swapping the wiring around and testing for spark, you should be able to track down the problem.

Which leads me to believe blue wire has issue. 0.2 ohm back to the pulse generator so I believe the wiring is fine

That only tells you the wire isn't open. You also need to test for shorts to ground and shorts to other wires in the same harness. Because so much has been apart, testing for shorts to ground from a pinched wire is critical.
It sounds like you have gotten a spark from each coil and each spark unit, but not from each pulse gen?

[gripitnripit]

Rambozo,

Thank you for your reply!

Such a simple thing I didn’t even think to do was test for shorts... I’m so deep into this thing it didn’t dawn on me. Duh

But yes, I believe what it’s coming down to is the yellow wire pulse gen is sending spark but the blue is a no go. Even though the tests on both seem to be fine.

AND I will add that sometimes when I push the starter or release it, I get a single spark from #4 or sometimes #3 but it’s rare and so sporadic. So there’s times when it wants to.

I believe you’re onto something, I may have short somewhere down the pike. Thanks again

[Maz]

Are you getting 12v to each coil?
Maz