I have a 83 GS1100G. When I put a voltmeter on the battery posts when the bike is running, I get voltage readings that jump all over. Within 5 seconds, the readings jump from 14.3, 7.5, 12.6, 14.7, 2.8, 13.2, .... on and on. Ive been reading the forum for weeks trying to figure this out. The engine runs rough when it is on and back fires in puffs. First the bike wouldnt start but it was turning over. I removed and cleaned the carbs. The Bike finally started when I added some starter fluid. Next I checked the coils and got 0 resistance readings. Bought and installed new coils. Removed the spark plugs which are new. They were black coated. Cleaned the plugs real well and had good spark. At this point, the bike would start but still ran rough with puffs in the exhaust pipes and fluctuating voltage at the battery. I installed a SH775 a few years ago. So I checked the stator. The AC voltage from the stators 3 wires were bad. 3 wires read 40-45V while the third read 5V. When I installed the SH775, I connected the 3 SH775 wires to the old R/R wires and connected the black and red SH775 wires to the battery. When I disconnected the stator wires at the original stator harness wires, the connectors were corroded and the ends of the wires were black and melted. When I checked the stator voltages the wires were disconnected from the harness. I checked the voltage at the battery and the readings were fluctuating still (I dont understand that at all). I installed a new stator from RMSTATOR today and retired the SH775 directly to the stator output wires. I ran the SH775 to a ground on the engine block and connected the red SH775 wire to the original red wire that connects to the harness before the fuse box. Moment of truth, the bike started right up but still had fluctuating voltages at the battery and puffs in the exhaust!! The difference before the new stator the fluctuating voltages never jumped above 13.0. After I turned the ignition key off the voltage reading on the battery was 14.4V. I turned the headlight on and the voltage dropped to 12.6. Sorry this is so long but wanted to provide as much information as I can. Please share your thoughts and suggestions. Right now Im thinking that I need to replace the SH775. This has turned into a quest.
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Fluctuating Voltage Readings at the Battery
- Thread starter Nash1100
- Start date
My god, please reformat your text if you want some help. At least put some paragraphs in there.
In any case, either your multimeter has crapped itself, probe leads are faulty or your connections on the bike are shot. Such wildly fluctuating readings are usually caused by intermittent contacts.
You had coils with 0Ω, so likely something has shorted on the bike - which should be handled by a fuse. But somewhere in there you're writing "black and melted", so something bad has happened.
Inspect, clean and replace as necessary all connections on the harness as a first step.
In any case, either your multimeter has crapped itself, probe leads are faulty or your connections on the bike are shot. Such wildly fluctuating readings are usually caused by intermittent contacts.
You had coils with 0Ω, so likely something has shorted on the bike - which should be handled by a fuse. But somewhere in there you're writing "black and melted", so something bad has happened.
Inspect, clean and replace as necessary all connections on the harness as a first step.
I second the art of sentence structure and paragraphs. I started to try and read that then just gave up. Two year olds construct sentences better than that.
Have not experienced such fluctuating voltage.
You said fluctuated when running. And talked about voltage with bike off and didnt mention fluctuations.
Have you tried disconnecting the R/R and then see if fluctuates when bike running??... then will know for sure if is related to the charging system.
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I ran the SH775 to a ground on the engine block
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Engine block? Try to frame or to the battery negative.
Have you checked the connection of the thick black wire on back of engine (top of transmission)?
The stock connection will be to the solenoid mounting bolt with a b/w ground wire from bike harness there too, and is recommemded to also run your own ground wire to there so not relying on that wire in bike harness.
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Thank you Redman so much for the reply and fixing my original post format. The multimeter doesn?t fluctuate when obtaining readings with the bike off. To disconnect the SH775, would I just disconnect the red output wire from the SH775 only? Or do I disconnect the input stator wires too?
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To disconnect the SH775, would I just disconnect the red output wire from the SH775 only?
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Yes. Could disconnect the stator leads also.
If I had to make a guess, I would suspect this fluctuation has to do with having the R/R ground to the engine block, so that current has to go thru engine block, and thru engine , thru mounting and/or engine ground ..... and the R/R is trying to regulate its own output voltage, and the connections are kinda far from the battery. (hard to explain) (and just somewhat making theories here).
To disconnect the SH775, would I just disconnect the red output wire from the SH775 only?
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Yes. Could disconnect the stator leads also.
If I had to make a guess, I would suspect this fluctuation has to do with having the R/R ground to the engine block, so that current has to go thru engine block, and thru engine , thru mounting and/or engine ground ..... and the R/R is trying to regulate its own output voltage, and the connections are kinda far from the battery. (hard to explain) (and just somewhat making theories here).
I?ll disconnect the SH775 wires this afternoon and start the bike. I?ll report the voltage results.
My previous post indicated that I attached the ground to the engine block (my ignorance of terminology). I grounded the SH775 to the back of the crankcase next to the ground point of the battery.
My previous post indicated that I attached the ground to the engine block (my ignorance of terminology). I grounded the SH775 to the back of the crankcase next to the ground point of the battery.
why so far? electrically, given the connection was good it shouldn't matter, but the frame is closer. If your starter spins with strength there's unlikely to be any problem with the original cable....and all the bolts attaching engine to frame ensure that the frame itself is also well grounded...
but for any place you want to ground to, Check the path from that place to the battery negative post....With the bike NOT running, There are two ways to do this...1) with an ohmeter on its lowest setting. The reading should be the same as with the multimeter probes touching each other..say 0 to 2.4 ohms depending on the meter..(this is called "zeroing the meter" many of which do not show "0")
or 2) get a test light and attach one probe to battery positive, the other to the place you want to attach ground. Use a brake light bulb for this or a turn signal bulb. It should be BRIGHT.
The meter itself IS a suspect. MOST Usually at the leads. Wiggle them, change them, test them...
I think you said you had a new stator. So, from that assumption,
... you might have AC loose in the system. This might explain the fluctuating voltage seen...a multimeter needs time to settle and fluctuating voltages will confuse it, . It might also explain a jerky ignition as it "confuses" the operation of coils. This might be caused by your R/R, as you are thinking. A blown rectifier will let AC by.
You might just see this as a flicker in the headlamp or tailight (but it'll be harder to notice there..) when the bike is RUNNING .A test light done the same as "2)" described above may also show it.
But before settling on an expensive new R/R, repair all the wiring problems you described..burns etc and LOOK for chafe points between the stator and R/R. After that, if you have one, swap a spare R/R in...any working one with 3phase connections should work.
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I disconnected the input and output connectors to the SH775. Still had voltage fluctuating readings on the battery with the engine running. Going to borrow a multimeter and test again tomorrow to eliminate faulty multimeter readings. On the bright side the bike starts up quickly like it never has before.
Very weird.... Does it have a headlight loop in the three stator wires? I don't think it'll help but if it does you can remove that & get it out of the equation.
Perhaps the it's electrical noise from the running engine upsetting your meter?
Perhaps the it's electrical noise from the running engine upsetting your meter?
When I took my GS1100E to get dyno tuned they thought I had a bad rectifier. The voltage was all over the place, with very high spiking readings at the battery. It turned out that the plug wires were designed for plugs with the screw on type terminal, not bare threaded like stock, and when he put them on the problem was solved. I am no electrical engineer, so I won't try to explain as I can't, but your situation sounded familiar. It's probably a long shot but thought I would share just in case.
What location on the frame is the best spot for the ground wire? When I verify if my meter is good or bad, I will definitely do your suggestions. As you can guess, I?m not electrically knowledgeable. I?m learning the hard way though. Sharing your knowledge and experience is greatly appreciated.
anywhere within reach of the groundwire that has a solid connection to the frame..ie:"
etc...
If the meter and probes are ok,
Any intermittent "load" will cause variation. You can see this yourself easily with the key on and the bike not running. Turn on a turn signal or brake light. Battery voltage will change as the light blinks.
You can pull the fuses from lights, turn signals, and brake light and still run the bike. This will allow you to cross them off the list. Intermittent shorts are fairly unlikely and will blow fuses if they are really bad but it helps to get all the "unikely" stuff off the list however remote.
However, if the bike is not running smoothly when running on battery alone, check the connections to the "Igniter", particularly to the ground. Also, chafe or connections to the ignition sensors.
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2BRacing
Forum Mentor
There should be a black wire with a white stripe with a ring lug on the end located under one of the starter solenoid mounting screws. There is also usually a similar wire with a ring lug located on one of the the battery box mounting bolts. They are the standard frame ground points.
Use the search function to look for "Single Point Ground" posts by a former member here Posplayr. He advised to collect all the frame ground wires at one point, such as the solenoid mounting screw. The ground wire of the R/R would also be located there, and an additional ground wire from battery -ve terminal to that single point ground (SPG). Leave the thick ground wire between battery -ve and engine case as it is.
I am not clued up on electricals, but according to Posplayr (an electrical engineer) the SPG setup minimises return current flows, which is good for the health of your bike's electrical system.
Bought terminal nuts and installed one on a plug. Couldn?t get the spark plug boot on the terminal nut. Guess the plug wires weren?t meant for terminal nuts. Also learned that the major auto parts store don?t loan multimeters...but they are more than willing to sell a cheap Chinese one for 30 bucks.
Going to borrow a multimeter from a friend to verify mine. Then follow all of your instructions for checking the fuses and ground wires. Will investigate the SPG further. I?ve read many posts on this site about an SPG but couldn?t find a post that instructs/ suggests where to locate the SPG. I?m not going to give up, I enjoy working on the bike but I love riding it.
Just pick a spot on the frame that you can bolt multiple ring terminals too. Run them all to there & a big one back to the battery.... 
