78 GS550 Dies in 3rd Gear

[Wangofree]

I've had good success with my GS550 rebuild. https://www.thegsresources.com/_foru...0-back-to-life
She purrs like a kitten but roars like a beast when I get her up and running.

Yesterday I installed a Dyna-S, timed it perfectly and it seems to idle great in the garage. I took the bike out today, 1st gear, no problem, 2nd gear, going great,
the second I shift up to 3rd gear the bike dies IMMEDIATELY. Red oil warning light comes on, etc. No revving, no engine wind down. It's as if I shut the bike off the minute I put it in 3rd. I then downshift to 2nd and the bike starts back up and runs fine. Back up into 3rd, bike dies, down into 2nd bike comes alive as if nothings wrong. Weird.

I can shift it up to 4, 5 or 6th gear and the bike will run. What is with 3rd gear? I feel certain there is an electrical issue but for the life of me I can't imagine what it might be.

Any thoughts will bring you good karma.

Thanks. Mike

[Rob S.]

I've never heard of anything like this, though it does sound electrical. Can you remove the Dyna and go back to the old?

[Wangofree]

Hi Rob, here's a video showing shifting up and down into 3rd and its sudden death.
I could go back to points, but that would definitely be a pain. I've installed a couple of electronic ignitions on other bikes
(Honda's) without any issues.

This is so strange that a mechanical action could cause an electrical reaction. I'm stumped, but I'll see if there was something I missed.

Thanks.

[1978GS750E]

Maybe check the gear indicator wiring for a short??? That is a strange issue for sure! Make sure you let us know what the issue was, when you get it sorted.

[Wangofree]

Ron, You might be on to something. For the Dyna S I tapped into a keyed 12v wire coming off the "plug" from what I thought was the key. It might actually be the gear indicator wiring that I tapped into. I should move that tap to perhaps the coil power and see what happens.

[rphillips]

Makes sense, 3 indicator light comes on & eng. dies, 3 indicator light goes off eng. starts back. Gear nor shift lever nor shift drum position would have nothing to do with electrical stuff. Very interesting.

[Rob S.]

Makes sense, 3 indicator light comes on & eng. dies, 3 indicator light goes off eng. starts back. Gear nor shift lever nor shift drum position would have nothing to do with electrical stuff. Very interesting.

True, but it's not without a very strong clue: it started with the replacement of the ignition, and always happens with the new, never happened with the old. That narrows it down quite a bit. Was any other work done on the bike at the same time as ignition upgrade?

On a car or truck, it's pretty easy to skip a gear. A bit harder on a bike.

[Redman]

Simple test: Disconnect the connector from the gear indicator switch.



Note: THe gear indicator switch operates by connecting the appropriate light to ground. So when you go into 3rd gear, the switch grounds out that wire, in all other gears it will have voltage on it (thru the indicator light).

[Wangofree]

Ah, problem solved. Like an idiot I tapped into what was the 3rd gear selector indicator wire. This morning I removed that connection and made the Dyna-S power connection to the keyed power running to the coils. Problem solved.

Dyna-S has made a huge difference in cold starts. It used to take a good 60 seconds with babying the choke until the bike was warmed up and would idle. Now it starts within 5 - 8 seconds and doesn't take near as long to disengage the choke with a smooth idle following.

Morale of the story kids, don't connect your electronic ignition 12v power wire to anything other than the coil power, or some other power besides your gear selector power.

Thanks guys for your collective thoughts. Mike

[rphillips]

Finding & fixing these little problems makes you feel good, don't it? Congrats.

[steve murdoch]

Nice detective work, Sherlock.

[metalfab]

Sweet, problems like that are a real challenge. When nothing makes any sense, always keep going.