1980 GS1000 no-start

[revilo]

Hi all,

I'm stumped and at the end of my rope. Hoping I can get a sanity check and some troubleshooting advice.

The subject is a 1980 GS1000. Stock, with CV carbs.

My bike began running poorly around 2020. In an effort to get it running well I pulled the carbs off the bike and followed the rebuild guide here. Didn't fix the problem, and the bike sat for a few years.

This spring, determined to get it running, I pulled it out and did the following:

Went through the carbs again. I pulled all the jets and needles. Cleaned everything surgically with carb cleaner and compressed air. Checked the float levels and bench synched according to the bwringer page. I didn't degang the carbs but pulled them down as far as I could otherwise. The carb boots are still supple and in good condition.
I checked the valves. They're all within spec, slightly on the looser side on the exhaust at 0.08mm.
Installed a Dyna-S ignition and new coils. (Left coil is cylinder 1 and 4, right is 2-3). Followed the instructions for install, including base timing (holding the rotor advanced until it just trips the light then locking it down). There is obvious spark when the ignitor fires. I'm confident in having 1 and 4 set properly. 2 and 3, the ignition timing mark is over the 23 on the rotor when the coils trip fully advanced. The voltages at the coils are what they are supposed to be according to dynatek.

Attempting to fire is not fruitful. I've tried with the airbox on, choked and unchoked. The bowls are filled and plugs are getting wet. I've tried airbox off, holding cardboard over the carb throats. This wets the cardboard with fuel. When I do this, it will sometimes catch briefly on cyclinders 2 and 4 before dying. It generally will not fire. I have had some massive backfires.

I consider myself reasonably mechanically able and have never been stumped like this before. It's driving me to drink. Suggestions on where to go next with my troubleshooting? Is the timing way off? Massive air leak I'm overlooking? Carbs not running right?

Thanks in advance for getting my old GS back to the road.

[Nessism]

Do you have good spark? Could the two coils be mixed up?

[chuck hahn]

I would revisit the installation of the dyna ignition first

[steve murdoch]

Dyna instructions.

https://www.dynaonline.com/amfile/file/download/file/5849/product/4355/

[Grimly]

Often if the coils are reversed, you get a massive bang from the pipes.
Not that I've ever done that, oh no.

[Big T]

You mention a Dyna S and an ignitor
those two are incompatible
The igniter is deleted with a Dyna S

[oldGSfan]

Often if the coils are reversed, you get a massive bang from the pipes.
Not that I've ever done that, oh no.

Yes that 'may' have happened to me, when I found the Dyna on my GS1000 was draining the battery due to miswiring and I investigated. I 'may' have put the pickup 180 degrees out of whack.

If plugs are truly wet it sounds like ignition but you sound like you'd know that anyway. What do you know about the bike's history, wiring, etc? What led you to land on carbs as the problem in the first place? Knowing what happened before it started running poorly will help others get the big picture, for example, if it sat for a while without riding before things went south. If it began running worse one day during continuous use I'd think of other things like ignition, exhaust leak, and inside the engine, unless....

Once while sorting out a couple of Suzukis after rebuild they both started misfiring, backfiring, not idling etc. I had been working on carbs (of course) but it finally dawned on me that I filled both up the same day from the same station. Drained and refilled the tank, problem solved. That was extremely mystifying until the light bulb went on. Hopefully the fuel isn't from 2020 .

Don't let it drive you to drink, that's what your significant other is for.