Several charging system diagnostic questions

[randyshipp]

First of all, here's the situation: I recently bought a 1980 GS850GL with something like 16,800 miles on it. I'm unclear as to what the FPO did or did not do, maintenance wise. All I know is that, 5 miles into my first ride on it, I stalled it at a light and did not have sufficient battery to start it back up. The battery took a charge later that night, and it starts now.

I attempted to go through the charging system troubleshooting procedures in the Clymer's manual, but ran into a few snags there.

1) The Clymer's manual says (for GS850 models only), one should open the fuse box and remove the two fuses attached to the orange/green and orange/red wires. This is problematic, since it's not possible to see inside the fusebox to tell how the fuse holders are wired in. I thought I'd be clever and check out the wiring diagram at the back of the book. Sadly, there's not one that says "1980 GS850GL". In any case, none of the diagrams for models similar to mine even show ANY O/G or O/R wires in the whole bike, let alone going into the fuse box. Now, I can see O/G and O/R wires on my actual bike, so I know I can't trust the wiring diagrams now. Sigh. Without cutting apart the wiring or the fuse box, how can I tell which two fuses they mean? And why do they want them removed before doing the tests with the voltmeter?

2) Undaunted, I went ahead an hooked the multimeter to the + and - terminals of the battery per the book and rev'd to 4000-5000 rpm. The reading was something like 16.5V. The Clymer's book said simply "replace rectifier/regulator" if the voltage was too high. Good advice?

3) Would the R/R from my 1982 GS850GL (project bike, not running) work in lieu of buying an expensive replacement?

4) If the answer to 3) is yes, is there any way to test the R/R *off* the bike before installing it, just to be sure it doesn't have the same problem?

Thanks in advance for any advice.

Randy...

[rustybronco]

Hello,

#2 IF the battery is fully charged and is in good shape(holds a charge) then yes 16.5v dc @ 5000 rpm is to high of a voltage.

# 3 yes the regulator from your 1982 gs850l will work.

# 4 yes you can check the r/r off the bike I did on mine from the info on the electrix site.

also check the stator papers in the garage section of this site.

http://www.thegsresources.com/garage/gs_statorfacts.htm

[randyshipp]

Hello,

#2 IF the battery is fully charged and is in good shape(holds a charge) then yes 16.5v dc @ 5000 rpm is to high of a voltage.

# 3 yes the regulator from your 1982 gs850l will work.

# 4 yes you can check the r/r off the bike I did on mine from the info on the electrix site.

also check the stator papers in the garage section of this site.

http://www.thegsresources.com/garage/gs_statorfacts.htm

Thanks for the tips. I'll look up "the electrix site" and will definitely re-read the Stator Papers.

Randy...

[Billy Ricks]

You can check you regulator/rectifier by following the Suzuki procedure below.

With the r/r removed from the bike, fins pointing up and terminals facing you, the terminals from left to right will be A, B, C, D, and E.
Negative probe on A and positive on B you should get 6-7.5 ohms.
Negative probe on A and positive on C you should get 6-7.5 ohms.
Negative probe on A and positive on D you should get 6-7.5 ohms.
Negative probe on A and positive on E you should get 50-70 ohms.

Then switch the negative probe to terminal B and place the positive probe on A, C, then D, you should get no reading. Positive on E should read 6-7.5 ohms.

Switch negative probe to C and positive to A, B, then D, you should get no reading. Positive on E should read 6-7.5 ohms.

Switch negative probe to D and positive to A, B, then C, you should get no reading. Positive on E should read 6-7.5 ohms.

Switch negative probe to E, positive to A, B, C, and D should give no reading.

The numbers have to be within range. It doesn't take much of an out of range reading to lead to the wrong output.

[randyshipp]

You can check you regulator/rectifier by following the Suzuki procedure below.

Excellent stuff! I'll definitely give this a try! This site is amazing...

Randy...

[Boondocks]

Re: Several charging system diagnostic questions

...The Clymer's manual says (for GS850 models only), one should open the fuse box and remove the two fuses attached to the orange/green and orange/red wires. This is problematic, since it's not possible to see inside the fusebox to tell how the fuse holders are wired in. I thought I'd be clever and check out the wiring diagram at the back of the book. Sadly, there's not one that says "1980 GS850GL". In any case, none of the diagrams for models similar to mine even show ANY O/G or O/R wires in the whole bike, let alone going into the fuse box. Now, I can see O/G and O/R wires on my actual bike, so I know I can't trust the wiring diagrams now. Sigh. Without cutting apart the wiring or the fuse box, how can I tell which two fuses they mean? And why do they want them removed before doing the tests with the voltmeter?...

I have a 1980 GS1100ET and on my wiring diagram the O/G would be the Signals fuse (turn signals, horn, etc.). The O/R would be the Lights fuse. On my bike these would be the uppermost two fuses in the box. I suppose that the manual was setting up a situation to test the electrics without any load (except the ignition fuse which is necessary to run the bike).

[randyshipp]

You can check you regulator/rectifier by following the Suzuki procedure below.

With the r/r removed from the bike, fins pointing up and terminals facing you, the terminals from left to right will be A, B, C, D, and E.

I had a little trouble with this. (First of all, getting the R/R off was nowhere near as simple as Clymer's led me to believe! I assume I was correct that removing the battery tray is the only way to access the screws holding the R/R on?)

Anyway, With the fins pointed up and the *wires* facing me, I observe a rectangular area from which five wires protrude. That rectangular area is filled in with some kind of resin- or epoxy-like material. The wires are not neatly lined up in a row, so it's not really clear which is B, which is C, etc. Can you reference these by wire color? Also, any way to identify the OEM piece vs. a replacement? Thanks!

Randy...