Bad kill switch

[Joe Guilbeau]

20141101_195107.jpg

So, putting it all together you can see where the Yellow/Grn wire is soldered to the outer ring of the round post connector, and the Orange/Wht wire is soldered to the center of the post.

Pushing the "Start" button connects the inner and outer connections on the round post and you now have 12Vdc going to both of your coils. Your wiring may have different colors.

[trucker]

thanks Joe for the pics better understanding of how all that works
ok so I just went out and double checked the 12v at the coils. So I disconnected the wire to the coil and connected the probes to the wires to the harness, with the ignition on I got 11.8 to 12v on my o/w and Black wire which is my 2/3 coil wires I hit the start button and then dropped to 9.3
now on to coil 1/4 which is the o/w and white wires I got 11.4 to 11.6 with the ignition on I then hit the start button and it drops to 8.4. Now I have not cleaned anything with contact spray yet I have to run out and buy some but that is on my agenda to do list

[JTGS850GL]

Clean the contacts first. Don't forget to clean the fuse connectors as well.

Those voltages you measured are still a little low. May not be the root cause of your problem with 2&3 but still a potential problem. Do the following just to verify:

Measure the voltage of your battery directly across the terminals with the ignition off:

Measure the voltage across your battery with the ignition on:

Measure the voltage at your coils O/W wires with the ignition on and the coils attached:

Use a good solid ground like the engine case or the negative battery terminal for all the measurements above. You should be able to probe the coil side of the connector with your meter probe. If you can't get the probe in there then use a small piece of wire to extend the probe tip and allow you to probe inside the connector. You could also simply puncture through the insulation after the connector with a pin and probe that.

Report back all the measurements.

We're not checking the charging circuit here. That's another issue to address. We're just verifying that the correct voltages are getting to the coils and if not why.

So far my guess is that the igniter is the source of your 2&3 problem but you have some possible voltage losses that will cause issues as well. No way to tell how much line loss you have without first knowing what the battery voltage is when doing the coil voltage tests. That's why I asked you to do the tests above.

[Joe Guilbeau]

Here is a wiring diagram of your (assumed) 1979 850G

http://members.dslextreme.com/users/bikecliff/images/1979_GS850GN_wiring.gif

[trucker]

ok here are my numbers
voltage of battery directly across the terminals with the ignition off is (12.4v)
voltage across your battery with the ignition on is (12.2v)
coils O/W wires with the ignition on and the coils attached (Coil 1/4) 10.2v black probe grounded to the frame
(coil 2/3) 10.1v black probe grounded to the frame

[trucker]

Thanks Joe the bike is a 1982 Gs 750

[Joe Guilbeau]

Here may be the Suzuki Service Manual for the GS750, looks to be a 1983 manual that may suit your bike.

http://www.mtsac.edu/~cliff/storage/gs/GS750E-ES_Shop_Manual_1983.pdf

Look in Section 6-5

[JTGS850GL]

ok here are my numbers
voltage of battery directly across the terminals with the ignition off is (12.4v)
voltage across your battery with the ignition on is (12.2v)
coils O/W wires with the ignition on and the coils attached (Coil 1/4) 10.2v black probe grounded to the frame
(coil 2/3) 10.1v black probe grounded to the frame

OK, you have some voltage loss but that can be addressed later. With those number and no spark on only 2&3 using the DVM trigger method, I'd say your igniter probably is the culprit. Once you get it replaced and regain spark on 2&3 you'll need to do some cleanup to get those voltages up to par. You should not be seeing a 2V drop between battery and coils. It's a long path between battery and ignition coils/igniter. Several connectors and a switch are in line. You can clean up the existing connections and get closer to spec. You may also consider doing the relay mod, but a good healthy electrical system shouldn't need it. Either way you should address this before you go further with the project.

[trucker]

ok that is what I was also leaning towards was the igniter time to order one thanks I will keep ya all posted