Funny charging ?

[OLIVER69]

Hi Guys
i m new to the forum and GS world , just bought a 1100 GSX (1981 model I believe ) , replaced the battery and checked the charging system ... we have a funny situation

new battery
at idle 12.7-12.8.12.9
at 2500 13 to 13.7 or so
at 4000 does not go up never goes in the 14

with lights on at idle 14.0 to 14.5
with lights on at higher rpm charge is dropping to 13 ...

something is not right ... any ideas ?

Oliver from Italy

[fastbysuzuki]

If you are getting 14-14.5 volts at idle with the lights on then your charging system looks ok, a loss of voltage at higher rpm generally means you have dirty contacts in you charging system wiring you need to clean them all and ensure your earths are good and clean.

[steve murdoch]

Have a look at the test from Poly to get some better readings.

https://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST&p=1272192#post1272192

[Redman]

Hi Guys
i m new to the forum and GS world , just bought a 1100 GSX (1981 model I believe ) , replaced the battery and checked the charging system ... we have a funny situation

new battery
at idle 12.7-12.8.12.9
at 2500 13 to 13.7 or so
at 4000 does not go up never goes in the 14

with lights on at idle 14.0 to 14.5
with lights on at higher rpm charge is dropping to 13 ...

something is not right ... any ideas ?

Oliver from Italy

Oliver,

Welcome to TheGSR.

THe fact that the voltage goes up with RPM tells you the charging system is working some (as opposed to being completely failed). THat 13.7 is high enough to keep you going, but could/should be higher for better results. If you have some bad connections, they are heating up and that can become worse problem. Big suspect could be the connections between the stator and the R/R. Other suspect could be the R/R output (red) wire where connected to the bike haresss wiring.

Also check what is called the OpenCircuit voltage of the stator. Disconnect the stator, and check AC voltage between each set of two legs, total of 3 readings. SHould be about 70 VAC ( let me again say "AC").

One minor point to discuss. In US was no GSX in early 80s, but I understand are pretty much the same as the US models. But in US could not turn off the headlight 80 and after.
In US, on years that could turn off the headlight, and with stock wiring, when turn off the headlight there is an extra contact in the headlight switch that opens up (turns off) one leg of the stator. So when turn on headlight then have all three legs of stator.

BUt even still, In general, the charging system doesnt put out much with engine at idle rpm. So, I would not expect to see that high of voltage at idle. Maybe just from reving just before. See if it stays that way.

Also, is it a 1100G (shaft, two valve per cyl, round cam caps) or is it the 1100E (chain,4 valve per cyl, rectangular cam caps). I suspect it is the E that was called GSX (GSX1100E) (GSX1100EX if include the model year designation).

[hannibal]

One minor point to discuss. In US was no GSX in early 80s, but I understand are pretty much the same as the US models. But in US could not turn off the headlight 80 and after.
In US, on years that could turn off the headlight, and with stock wiring, when turn off the headlight there is an extra contact in the headlight switch that opens up (turns off) one leg of the stator. So when turn on headlight then have all three legs of stator.

This was my first thought. Not sure if the stator is failing and can't produce enough output with just 2 of the 3 legs. Maybe with the headlight on and the third leg working it can produce more output.

[allojohn]

Yep, mod the stator removing the leg to the light switch and connect all three legs directly to the R/R, then do the quick-test.

[OLIVER69]

Thank you guys for the welcome ! so yes its a gsx1100 e dohc 16v

i tried today the stator test its pushing 60V at a steady 4000 rpm all same on all 3 wires

meanwhile the diode test on the R/R I don't think it went too well it was always 1v so from the chart I found on the forum should be bad ...

a friend will help me tomorrow and we ll try to perform all tests again just to rule out my incompetence

all help + suggestions it is welcome

ciao

[OLIVER69]

Thank you Redman for your tips
I think we found the problem , we checked again and ran the red output wire from R/R direct to BAT+ and black to BAT- and looks like it is charging as it should.... 14.8 at 4000+ rpm , so tomorrow back in to the garage to fix the problem for good !