Voltage issues...

[pjmcburney]

This question may have been answered in an existing thread - if it has, please post a link.


I'm having dramas with voltage spikes on my GT750L.
I've been using a solid-state regulator from Oregon on the bike for a some time with no problems until just lately.

On a recent interstate trip I got stranded when all of the lights, the gear indicator and eventually the fuse died when the voltage went sky-high.
After getting the bike home I diagnosed a dud alternator rotor (dead short across the windings), but I'm unsure as to whether it was the cause or the result of the over-voltage situation.

Everything went ok for a while with a replacement rotor until last night when again a voltage spike took out the head and tail lights leaving me with just indicators to guide me in the pitch black on the way home to my place.
At least the fuse didn't melt this time...

Having read a couple of posts in this thread it seems the Oregon reg's may not be all they're cracked up to be, or may not be well designed for Suzukis.
A mate who's knowledgeable in electronic ways informed me that solid-state reg's can stop regulating at certain voltage levels, allowing the voltage to climb quickly beyond that level.

So, will the Oregon reg's allow the voltage to 'break through' at a certain level (e.g. when there's a fault in another part of the charging system that causes voltages to climb)?

Any ideas as to what may be causing this to happen - could I have wiring, charging or earth faults somewhere?

Should I go back to an OEM regulator - will it better regulate high voltage situations without breaking through?

Thanks in advance...

[oldjapanesebikes]

I'm just wondering why you think it was an over voltage rather than an intermittent short somewhere in the harness ? Another fellow on the board had an intermittent problem with the harness chaffing through behind the electrical component panel where it was rubbing on the rear fender - given the winding on the alternator was gone it could be worth a close look as the alternator harness connects in that same area.

[pjmcburney]

I'm just wondering why you think it was an over voltage rather than an intermittent short somewhere in the harness ? Another fellow on the board had an intermittent problem with the harness chaffing through behind the electrical component panel where it was rubbing on the rear fender - given the winding on the alternator was gone it could be worth a close look as the alternator harness connects in that same area.

Oh it was definitely an over-voltage.


Just prior to the lights ceasing to work, they were really, REALLY bright.

But, I haven't checked the into harness too deeply, so that's good advice - I'll look at it on the weekend.

[jabcb]

The GT750 wiring diagram is shown in the electrical category under the wiring diagram sticky topic:
viewtopic.php?f=29&t=4743

The voltage regulator controls the voltage at its connection to the hot (orange) wire. Voltage at the battery is normally a little higher because of the voltage drop from the battery to the voltage regulator.

The GT750 voltage drop was discussed in a prior topic: viewtopic.php?f=29&t=5458

A problem with the wiring could increase voltage drops to the point you are burning out bulbs even thought the voltage regulator is working correctly. The wiring problem could also be intermittent, so that everything is fine most of the time & then suddenly you get burned out lights.

If you swap out the voltage regulator when you have an intermittent wiring problem, everything could be fine for a while until the wiring issue occurs again.

As oldjapanesebikes suggested, you should look for wiring problems. Checking voltage drops might also help point you to where a problem is.

[rbond]

I agree it is most likely a wiring issue. IMHO it seems a ground is not grounding thus sending excess voltage up the wires instead to ground and/or passed off as excess heat.

[Suzsmokeyallan]

Paul its possible the Oregon regulator may have been the culprit but there's too many other problems to look at and trace to find the problem and I was the guy who had the problem Oldjapanesebikes was referring to.

Here's how that whole electrical scenario played out, the bike was bought in 2007 and had some issues, one of them being a wiring problem of sorts in the past.
A brief history was it used to blow main fuses, melted the fuse holder a few times and generally be a pain the butt with its mysterious electrical issue that killed the system whenever it felt like it.
All of this I did not know when I bought it, only finding out after a while of owning it so I came in late to the game.

I set about a rolling restoration while still riding it every summer I went to Canada in August.
In doing so and riding it around the city, it used to drop the left cylinder only at idle sometimes, which led me to replace the plugs, points and condensers and re-check the timing.
It still had the problem at times which then had me checking the coils and plug caps next but nothing showed up as this issue would come and go weeks at a time, and even then only briefly.
Then one summer the bike mysteriously drained the battery while riding in town and I was again left wondering what this problem was.
It had in an Oregon regulator at this time and the charging looked to spec when I checked it so in went a spare battery and everything checked out ok again, so I pressed on still thinking about ripping the whole harness out and looking it over when I got back from that years trip to Vancouver.
However on that trip it acted up again when a few hundred miles from Calgary and this time the rectifier lost a diode which killed that battery.
I had to buy one on the road and get another rectifier sent to me from member Buffaloguy and return back to Calgary,Thanks again Fred for your swift action. the return trip is about 700 miles of riding and not one issue.
Anyways it went back working normal again and I was still thinking as to what was really going on with this issue when I left Canada that summer.
Next summer I pulled the front harness out and restored it amongst other restoration work, and took the bike to Vancouver for that years trip. Talk about testing fate right in the face.
Again when hundreds of miles from Calgary it lost the left cylinder at idle, then went back working ok for a few more days.
Then it lost the cylinder completely on Vancouver island while riding to Victoria, and I was forced to pull over and bridged the cap to plug a few times which caused some backfiring, it went back working normally,,,,again as usual.
This summer I used the Bandit and so I had some time to pull the GTs back harness out to go through it and find this gremlin.

And there it was, hidden behind the electrical panel, the alternator phase wires were moved in the past by someone and two were rubbing on the metal inner fender. They had chaffed the pvc to the point they were shorting to ground when the conditions were right for it.
This could have been the cause the rectifier fried a diode the previous year as shorting things to ground is not good for any electrical components.
I was lucky the alternator didn't burn the windings or burn off the brushes or in a worse case start a fire behind the electrical panel while riding.
To add to this, the points wire to the left cylinder had the same issue, and this was the problem for the on and off dropped cylinder issue at idle.
The reason the problem can come and go is that the vibrations of the bike when running does not allow for a permanent short to ground condition.

Your issue is different but still electrical so I would suggest you look at the following to check these areas:

The ignition switch connector in the headlamp if its looking melted/distorted replace/upgrade it to a large four pin socket and check the switch internals or try a known good one.
Remove the fuel tank and look at the connector that joins the two main harnesses, if it looks suspect, upgrade it to a large four pin type.
Also you could also remove the electrical panel and check the wires location and routing behind there for confirmation of no shorting.
Another item to check is the wires from the alternator as they pass under the engine to the electrical panel for any chaffing of the sheathing by the places where it comes into contact with clamps and the frame.
Finally, check and clean all grounds as they can be a major issue.