Bike dies when I let off starter

[Guest]

Hey guys I have a 77 gs750 and I've been having trouble getting it to run. I just recently replaced the stator with a caltric stator and I wired it directly to a new Sh-775 r/r. I have that grounded directly to the battery and have the positive hooked up to the oem fuse line. I just wanted to give some background of some electrical work I've recently done.

Now the the problem is that when I start the bike up with the starter button she starts right up. But when I let go of the button it dies. I e held it for a couple of seconds and seems to idle fine but always dies when I let go of the button. If gone crazy checking all the connections and grounds and switches and can't seem to find the problem. It's driving me crazy. Any advice?

Brand new battery if tried testig a couple spots with a multi meter and the connections I've tested seem good. Is it a short? Or could it be bad coils? Also the headlight does not seem to work. Just a kilt toe extra info

[Steve]

Sounds like a couple of wires from the right handgrip are crossed.

There should be a couple of orange wires with a white stripe (O/W), one of them will have a red band on it near a 3-pin connector. The third wire will be Yellow/Green (Y/G). The O/W with the red band should be 'hot' when the key is on. The other O/W will be switched with the 'kill' switch. The Y/G will be hot when the starter is pressed.

Let us know if that is what you have. If so, we need to move downstream with the troubleshooting.

.

[ttfraz]

I just had it apart yesterday. On my bike there is an orange wire that becomes hot when the key is on and then the orange with white coming out of kill switch and the yellow and green coming from the starter. All the connections seemed ok

[Steve]

By "all the connections seemed ok", may I presume that you TESTED them with a test light or a meter?

Follow the O/W and Y/G wires, especially the Y/G. That wire should go to the starter solenoid. (I don't think the '77 bikes made the detour through a clutch "safety" switch.) By your description, it sounds like the points or the coils are getting power from this wire, instead of the O/W wire.

If that checks out OK, follow the O/W wire that feeds the coils to make sure it is not getting power somewhere other than the 'kill' switch.

.

[ttfraz]

When I checked the o/w wire with the key on and kill switch in the on position I'm reading about a volt les than what I'm getting at the battery which is brand new. I haven't been able to get back to the bike. Won't until after work and I'll run some more tests on the wires around the kill switch / starter

[Steve]

One volt less is typical. Not all that desirable, but typical.

.

[ttfraz]

So I've played around with it a little bit. Now it only fires on one coil unless I have the starter button held.

Let it me try to explain. I start it up all plugs sparking. I let off the button the bike continues to idle but touch because of no spark on 2 and 3 which comes from the same coil. I figure bad coil. I test them and I switch leads coming from the dyna s ignition and the bad coil works which makes me think it's a wiring issue. Could it be a bad dyna ignition? The p o put it in not me but at the same time if it was a bad ignition then that one lead from it would be bad no matter what. Yet it it works with the starter button pressed. But it's only one wire coming out of the starter button. Not two. So it should affect both but it doesn't. Perhaps I'm over thinking this

[ttfraz]

Any ideas. Why would only one coil work after the starter button is released?

[Steve]

OK, now we're stirring a few more ingredients in the pot. At first, it was only mentioned that you had replaced the stator and R/R.

NOW, we find out there's a Dyna ignition on there, too. Any OTHER changes/upgrades/modifications?

You are simply going to have to go back to basics here. Did you install the Dyna? Doesn't really matter, but you will have to follow EVERY wire that is ignition-related (fortunately there are not very many) and verify that it is connected where it is supposed to be and NOTHING else is connected to that wire.

One possibility is as I tried pointing out earlier, something besides the starter solenoid is connected to the starter wire. What wire is only "hot" when you are pushing the button.

Check the power and ground connections for the Dyna. Don't just look at them, VERIFY that they have good connections.

And also keep in mind something that I learned many years ago: if you have some really screwy things going on, it's probably a bad ground.

.

[ttfraz]

Only other mod was a digital flasher. But that was a plug and play and has been working fine for a while. But I took a apart every wire I found remotely around the coils and ignition. I took apart and cleaned all my grounds. Replaced a few connections that the the p/o had done with bad splices. Tested a couple connections with multi meter. Everything checking out. I rerouted power sources straight to the battery to test the hot wires. Still nothing. The only think im not sure how to test is the dyna ignition. It seems like I would want to test those black boxes that replace the points but I'm not sure how to test them. The seem like a sealed unit

[ttfraz]

After going through every wire I couldn't find anything. So i figure it must be a bad ignition. Injustbordered a new one. Also I've been seeing some mention of a coil relay mod. Can some one point me in the right direction of what this is?

[hjfisk]

Where. In Ma. Are you? You seem to be ignoring the info that has been given to you. If it is only firing a coil when the start button is pressed it is obviously getting power from that circuit somewhere. You need to retrace your steps and wiring

[Brendan W]

http://members.dslextreme.com/users/bikecliff/

Coil relay info and much more is here.
Coil relay powers the coils almost directly from the battery and avoids the inevitable voltage drops in the lockout safeties and various plugs.
I was thinking your problem sounded like a badly half executed coil relay mod. If someone used the green/yellow wire to pull in a coil relay it would only work for as long as the start button was held. Why only one side ? PO ingenuity is boundless.
I think it unlikely your ignition is the culprit.

[ttfraz]

Where. In Ma. Are you? You seem to be ignoring the info that has been given to you. If it is only firing a coil when the start button is pressed it is obviously getting power from that circuit somewhere. You need to retrace your steps and wiring

Newburyport. I have retraced all the wiring and connectors. With a multi meter. There definitely hasn't been a coil relay mod done to the bike. I'm just at a complete loss. After testecimg all the connections. Perhaps I'm just not testing them at the exact right time. But from what I read in a couple other posts that perhaps one of the ignition sensors is burned out

[ttfraz]

I figure that maybe when the starter is pressed that the ignition is getting a stronger power source of power to the faulty ignition sensor and that with all the voltage drops here and there that the bad half of the ignition is just crapping the bed