Grounding/wiring GS425

[gspower]

"There should be a thick black wire from ve- to the back of the engine cases."
That must be what I am missing. The only ve- I have is currently running to the SPG.

The battery (+) to solenoid (+) is intact, as well as the lead from the solenoid (+, again, yeah?) to the starter (+), as well as the starter (+) to the black and white wires under the gas tank.

Now where exactly does -ve run to the back of the engine cases?

Edit: Are we sure this even exists on a 425? Can't say I ever remember a ground to the engine case .... but seems I can't really remember a time free of electrical problems, either. On the last known running configuration I had the R/R (-) routed directly to ve-.

[posplayr]

"There should be a thick black wire from ve- to the back of the engine cases."
That must be what I am missing. The only ve- I have is currently running to the SPG.

The battery (+) to solenoid (+) is intact, as well as the lead from the solenoid (+, again, yeah?) to the starter (+), as well as the starter (+) to the black and white wires under the gas tank.

Now where exactly does -ve run to the back of the engine cases?

Edit: Are we sure this even exists on a 425? Can't say I ever remember a ground to the engine case .... but seems I can't really remember a time free of electrical problems, either. On the last known running configuration I had the R/R (-) routed directly to ve-.

Electricity runs in circuits. All the current going from the positive post of the battery to the starter has to return to the negative side of the battery some how. What is attached to the negative terminal of the battery? It should be the case ground.

[gspower]

Electricity runs in circuits. All the current going from the positive post of the battery to the starter has to return to the negative side of the battery some how. What is attached to the negative terminal of the battery? It should be the case ground.

All that is currently connected to negative terminal of battery is the SPG at the solenoid.

[Gorminrider]

There is a wiring diagram for the 425 in the back of the Clymer manual available here:
BikeCliff's Website

The battery negative has one a large gauge wire attached to the motorcycle frame. Not the engine.but it don't matter except to the length of the cable.
The starter motor is "grounded" to negative via the engine mounting bolts from the frame...because internally, the brushes of the starter are attached one end to the big red cable, the other to the metal shell of the starter.."grounded". I am getting that you have done something as a negative post also connected to the negative battery post for convenience of "grounding" other devices. That's fine, but it must also have excellent connection to the frame.

The solenoid will not click when you bridge the two large bolts. But there should be a large spark and the starter should spin. If not, given the battery has been "grounded" as above, there could be a fault with the starter motor-very common problem....take the starter motor out and bench test it.It may need cleaning up.especially at the brushes. New brushes may be needed. This usually fixes them.
according to the diagram, your solenoid has another smallish wire green/yellow that runs to the starter button on the handlebar but it may be interrupted by safety switches...clutch I suppose, and then the kill switch etc eventually getting power from Orange which gets power from RED when the key is turned to on.... It's a lot to follow, I know but It should click when you push the button or when you provide + voltage to the green /yellow at the solenoid...This click represents a large contact plate moving to connect the two large discussed above, per starter. The two large posts on solenoid are therefore +, but only one is "live" until the contact plate connects them.. The screwdriver is a substitute for this contact plate.

on Suzukis., a black wire with a white stripe is on its way to "negative ground " Wherever else they go, they often end screwed to the frame.

[gspower]

I will ground the battery directly to the frame, instead of solely to the airbox, and post back. As far as the clutch switch goes I have already disconnected the two relevant wires in the headlight bucket. The starter relay would not click at all if this were engaged. I hope this is it *crosses fingers*.

[Brendan W]

http://www.cmsnl.com/suzuki-gs425-e-1979-usa_model16012/partslist/92081.html#results

This fiche is for the 79 E model. They are all most likely similar. Cable 7 in the Battery Schematic is the supply +ve to the solenoid. Cable 6 is the return to the battery -ve from either the crankcase or the frame. The starter motor has no ground cable as such and uses the crankcase as the first leg of the return path which is completed to the batt -ve with the cable.
Don't worry about the absence of the wire from the SPG in the schematic. As mentioned here already they had different quirky ideas about grounds back in those days.

[gspower]

http://www.cmsnl.com/suzuki-gs425-e-...1.html#results

This fiche is for the 79 E model. They are all most likely similar. Cable 7 in the Battery Schematic is the supply +ve to the solenoid. Cable 6 is the return to the battery -ve from either the crankcase or the frame. The starter motor has no ground cable as such and uses the crankcase as the first leg of the return path which is completed to the batt -ve with the cable.
Don't worry about the absence of the wire from the SPG in the schematic. As mentioned here already they had different quirky ideas about grounds back in those days.

The frame ground was the problem. I mistakenly assumed that my one point ground on the shock-resistant (rubber mounted) airbox was enough of a ground. I ran another lead from -ve to the frame and it started right up.

Interestingly enough, there was a broken connector loop on the bolt that I grounded the battery to. It would seem that at one point in time the bike was grounded to the same spot. PO must have lost it or forgotten about it. When I purchased the bike I had a ton of electrical problems. This seems to be the problem. I checked with a cheap multimeter and at idle I am getting between 13.x and 14.x volts. At 5k rpm I am getting 14.x-15.x volts. After a quick ride and turning the bike off, battery read at 12.9v. Seems pretty good to me.

I have a lot of work to do before I can conduct further testing (painting parts, cleaning carburetors, ensuring there are no leaks in the airbox) before I take it out for a long spin but I am very happy with the results.

Brendan W, Posplayr ... thank you both SO much. I really appreciate the help.

[posplayr]

Note all charging current from the R/R go out the red R/R(+) and have to return on the black R/R(-) so therefore the standard Single Point Ground (SPG) recommendation is:

SPG has three wires in:

• Frame ground (16 ga or larger)
• Battery Ground (16 ga or larger)
• Harness Ground (stock is fine 18 ga or larger)

SPG has one wire out:

• R/R(-) (14 ga or larger)

usually SPG is close to the R/R so that length is not longer than 12"

SPG is convenient on any mounting bolt on the side plate for side plate mounted R/R's.

It is really just that simple and has been described enough time, I don't know how to state it any simpler.

[gspower]

Note all charging current from the R/R go out the red R/R(+) and have to return on the black R/R(-) so therefore the standard Single Point Ground (SPG) recommendation is:

SPG has three wires in:

• Frame ground (16 ga or larger)
• Battery Ground (16 ga or larger)
• Harness Ground (stock is fine 18 ga or larger)

SPG has one wire out:

• R/R(-) (14 ga or larger)

usually SPG is close to the R/R so that length is not longer than 12"

SPG is convenient on any mounting bolt on the side plate for side plate mounted R/R's.

It is really just that simple and has been described enough time, I don't know how to state it any simpler.

As I stated, my SPG is on the sideplate under the solenoid. My R/R is grounded there, as well as my harness. It is then grounded to the battery, which is in turn grounded to the frame. I suppose I should also add an additional frame ground to the SPG so as to complete the circuit more easily, yeah? I am reading up on some material that you recommended - thank you for the suggestions.

[posplayr]

As I stated, my SPG is on the sideplate under the solenoid. My R/R is grounded there, as well as my harness. It is then grounded to the battery, which is in turn grounded to the frame. I suppose I should also add an additional frame ground to the SPG so as to complete the circuit more easily, yeah? I am reading up on some material that you recommended - thank you for the suggestions.

That one is not additional.....................

[gspower]

That one is not additional.....................

I assumed the SPG was the frame ground. I assumed wrong.