Dash/lights/starter won't turn on, battery seems fine.

[Guest]

Hey guys, new 79 GS550E owner here. The other day my bike shut off when I came to a stop at a stop light. It seems to be an electrical issue. I've been doing tons of reading on the mechanical side of things, but zero on electrical, so I'm a little out of my element here. I have a multimeter that reads the voltage on my battery at ~12.4 or 5 (not at home currently and can't remember the exact reading), so I believe my battery is fine? When I turn my key to the on position nothing happens. Dash, lights, when I try to turn the ignition, nada. So it would appear I have a fault somewhere directly after the battery, correct? I looked through a couple of BassCliff's electrical guides and he mentions a fault finding chart, but I can't seem to find it anywhere. Any help? Something super obvious I'm overlooking?

BikeCliff's website also seems to have a wiring diagram for tons of different bikes, but a 79 GS550E doesn't appear to be on there. Is there another model that I can look at that is on there with the same wiring diagram?

Sorry for so many questions, I'm a new bike owner who is eager to learn and trying to take in as much as possible.

[Steve]

Have you checked your (one and only) fuse?

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[GSCafe]

Have you checked your (one and only) fuse?

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Mine seems to be missing! The PO seems to have wired it out of the circuit. I still have the box that it came in and plan to address this. For me it was a small translucent box on the starboard side with red wires and a spot for only one fuse.

[tom203]

Mine seems to be missing! The PO seems to have wired it out of the circuit. I still have the box that it came in and plan to address this. For me it was a small translucent box on the starboard side with red wires and a spot for only one fuse.

If PO decided fuse was optional, be suspicious! This 425 diagram should be similar- shows how power flows from battery to fuse, etc

https://onedrive.live.com/?cid=2370B62DDF9F0C6B&id=2370B62DDF9F0C6B%211032&sc=documents&v=3

[BBoh21]

Have you checked your (one and only) fuse?

.

I opened up my fuse box (I have four, not one) and looks like my 15 amp main fuse was blown. I won't be able to put a new one in until tonight to be positive but that should do the trick. So I just need to pick up a glass tube fuse that's labeled at 15 amps right? Any additional specs I need to make sure I'm buying the right fuse?

[tom203]

To BBoh21..... You got 4 fuses ? Your wiring is likely like this 79 gs850 not like the gs425 pen

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

15 amp fuse at autozone, is fine Make sure you get a few- you might need them to determine your problem

[Steve]

I opened up my fuse box (I have four, not one) ...

You have four fuses?

You sure you have a '79?

What shape is your front master cylinder? Rectangular or round?
Do you have VM carbs or BS carbs?
Do you have points or electronic ignition?

I am betting that you have an '80 bike that was MADE in late '79 and some Bozo at the DMV office titled it as a '79.

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[BBoh21]

To BBoh21..... You got 4 fuses ? Your wiring is likely like this 79 gs850 not like the gs425 pen

Yep, not in front of my bike at the moment so this may be wrong but I had a 15 amp main fuse, then three 10 amp fuses for ignition, lights, and turn signals I believe. The diagram for the 850 you just posted looks more accurate than the 425, but I'm still working on figuring out how to read those diagrams.

[BBoh21]

You have four fuses?

You sure you have a '79?

What shape is your front master cylinder? Rectangular or round?
Do you have VM carbs or BS carbs?
Do you have points or electronic ignition?

I am betting that you have an '80 bike that was MADE in late '79 and some Bozo at the DMV office titled it as a '79.

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The previous owner said it was a '79 and the VIN comes out as a '79 as well. It has a kick start and electric start on it, which I read that '79 was the last year they put on both. I can't speak off the top of my head as to the rest of your questions Steve (like I said, newbie still learning).


Edit: googled front master cylinder, if it's the front brake fluid reservoir on top of the handlebars like it seems it is, then mine is round.

[Brendan W]

The previous owner said it was a '79 and the VIN comes out as a '79 as well. It has a kick start and electric start on it, which I read that '79 was the last year they put on both. I can't speak off the top of my head as to the rest of your questions Steve (like I said, newbie still learning).


Edit: googled front master cylinder, if it's the front brake fluid reservoir on top of the handlebars like it seems it is, then mine is round.

This where the fun starts. Mine is 81 and has a round reservoir. Most likely a PO replaced it.

[Redman]

BBohp21,

Buy a pack of 15 amp fuses.

If it blows as soon as you put one one back in, before turn on the key: find the regulator/rectifyer ("R/R", usally on side or bottom of battery box, the aluminum finned thing) and disconnect it, see if next fuse does not blow. And if you want more evidence, plug it back in and see if the fuse blows.
Bike will run without the R/R connected, with a good main fuse, just will not be charging the battery, and running entirely off the battery.

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[BBoh21]

BBohp21,

Buy a pack of 15 amp fuses.

If it blows as soon as you put one one back in, before turn on the key: find the regulator/rectifyer ("R/R", usally on side or bottom of battery box, the aluminum finned thing) and disconnect it, see if next fuse does not blow. And if you want more evidence, plug it back in and see if the fuse blows.
Bike will run without the R/R connected, with a good main fuse, just will not be charging the battery, and running entirely off the battery.

.

I take it this be to test if the R/R is the culprit behind blowing the fuse? The R/R regulates voltage coming from the alternator while the bike is running, and a faulty R/R would not regulate it and overload the electrical system causing the blown fuse... am I getting that right?

[tom203]

While you're checking out what Steve asked, try to determine if this bike appears to have separate rectifier and regulator rather than a combo unit that's found on later years.

[eil]

I had the same thing happen to me on my 850. Running fine, pulled up to a stoplight in a left turn lane, idled for a bit and then simply died. The main fuse had blown. Later I discovered that the PO had mixed up the fuses and put a 10A fuse in the spot for the main circuit (which should have been 15) and put the 15A fuse in the lights circuit (which should have been 10).

I guess what I'm saying in a roundabout way is make sure you have the right fuses in the right spots. And also know that fuses can go bad with age. My hypothesis is that the metal filament inside the glass is subject to vibration which weakens the ends where it is bonded to the terminals.

[Redman]

I take it this be to test if the R/R is the culprit behind blowing the fuse? ................

Yes.
SInce the fuse is blowing quite regularly, can disconnect the R/R to remove it from being able to blow the fuse.
Do replace the fuse, and the bike can run without the R/R, and if go a lot longer than you had before, well, then you can surmise the R/R is-has been-was the problem. Can run bike a long time, just are not charging the battery, but do need to get back to a charger.

........... The R/R regulates voltage coming from the alternator while the bike is running, .............

YES. The R/R is a regulator.... and....

Although a matter of definition.
Your bike has a stator, which is a 3 phase AC generator, and that goes to your R/R which is a seperate device, and that Rectifies the AC to DC and Regulates it to, say, 13.5 volts.
(and to further confuse things, GSes prior to say, 78, the rectifyer was a seperate device and the regulator was a seperate device)

An "alternator" is a name used to describe a device that is all that in one unit (mechanical spin goes in one end, and 12vdc current comes out the other end), which these suzukis dont have, but is common in automotive since the 40 & 50S and Honda mocykle sine the mid 70s and BMW mocykls for as long as I have known (some you can see it, looks rather automotive, belt driven and all).

........ and a faulty R/R would not regulate it and overload the electrical system causing the blown fuse... am I getting that right?

A fault R/R can fail in a few differnt ways:
1- have an intenal fault that shorts your DC power to ground, and blow the fuse as soon as it is connected. (the situation we suspect here in this case)
2- not regulte well so have way high voltage
3- have an internal fault that essentially shorts out the stator and burns out the stator.
4- not regulate well so have way low voltage (although that usally a wiring problem or stator problem)

Sometimes exhibits both symptoms 1 & 3.

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