1979 Suzuki GS850 acts like it has no power.

[jjtravis1]

I have replaced the battery and got a new r/r for it but it show a reverse bias of 1.8 so I'm thinking it's bad. But for some reason the bike acts like it has no power anywhere even though my multimeter shows a good charge to most systems. It's getting frustrating when not even the horn works.

 

[tom203]

Explain reverse bias...
"shows a good charge to most systems." just where are you measuring this "good charge"?

is this a new to you bike? or old friend behaving badly?

 

[LAB3]

Mine did the same thing last weekend, turned out the stator tested bad. Sure enough when I pulled it out it was melted in one spot and shorting, I'd test the stator.

 

[Redman]

I have replaced the battery and got a new r/r for it but it show a reverse bias of 1.8 so I'm thinking it's bad. But for some reason the bike acts like it has no power anywhere even though my multimeter shows a good charge to most systems. It's getting frustrating when not even the horn works.

Welcome to TheGSR.

Good that you have a muiltimeter.

Explain "revers bias". Do you mean you are measuring voltage output (red wire) of the r/r with it disconnected? If so, that is of no use.
HAve r/r connected, Measure battery voltage with bike off ignition off headlight off, then again at idle headlight on, and at 4000 rpm headlight on (for more detail find the "quick test", or report voltages here).

Explain no power everywhere.
Use meter, measure voltage at the fuse block, black lead on battery negitive and red lead on various points on the fuse block at first. At some point, maybe the main fuse, move the black lead to some ground wire on the bike, say, the black/white wire at the fuse block and see if get the same voltage reading. If it is much less, then is a grounding problem that will effect everything. If about the same, then you know the wiring harness black/white wire is well grounded and can then proceed, and put the meter black lead on about any convienet ground point or any convient balck/white wire. THen later, in your probimg around, if happen to measure no or low voltage somewhere, before deciding that something is bad, check your self by moving the meter balck lead back to the battery negitive.

Explain acts like no power everywhere but meter shows good charge to most systems.
Again, let me say, when measuring voltage (using meter red lead) at some place in the system you are concerned about: Lets be concerned about where you have the meter black lead. Try taking the reading with black lead on nearby black/white wire, and try again on a frame ground and try again on battery negitive. THe reading should all be about the same. If they are, then you can use withever is more convenient at the time (but check again if you think is a problem with what you are measuring). If they are not the same, then the problem is with the ground wiring, and maybe not a problem with the item you were trying to take the voltage reading.
(this is hard to explain to someone that doesnt understand it. But once you do understand it, is easy, but still hard to explain.)

Does it crank over with the starter button?

Does it start?

You say you replaced the R/R. I assume because was some problem with the charging system. How did you check the stator at that time? Or did you replace the R/R because of this "acts like no power".....?

Every Suzuki 850 is shaftdrive.
Prior to 1980 was the one model, GS850 (had kick start, headlight on/off). 1980 and after (no kickstart, no headlight off/on) was the GS850G and GS850GL .

 

[jjtravis1]

the r/r is from what I understand is only supposed allow electricity flow one way at at around 0.5 volts. it does that but it also is allowing electricity to flow backwards at 1.8 volts when it should be open line. all fuses test good. but I have no horn, no turn signal, no light, no dash lights. it's like the battery is not there power. oh and I can't start it either.

 

[tom203]

Disconnect this new r/r from the harness.....is there enough battery juice to power dash lights? You can use a NON running vehicle to jump the bikes battery for testing.
Is this a new to you bike??

 

[Steve]

Let's go back to basics. How are you checking this reverse bias?

The only way to properly check the rectifier portion of the R/R is to have it out of the circuit. Then, with the red lead of your meter clamped to the red output wire and the meter in diode check mode, touch the black meter lead to each of the three stator inputs. Note the readings. Now reverse the leads, put the black meter lead on the red output lead and touch each of the inputs with the red meter lead. In one set, you should see "OL", indicating overload, in the other set you should see about half a volt, maybe .6 or so.

Now repeat those tests on the black/white ground lead of the R/R. This would be a total of 12 readings. If any one of them fails, the rectifier portion of the R/R is bad. The only way to check the regulator portion is to start with a good regulator section and have the bike running.

.

 

[jjtravis1]

That's what i did. Foward bias was 0.5. Revers bias was 1.8.

 

[jjtravis1]

It has a new battery with full charge but no lights.

 

[Redman]

the r/r is from what I understand is only supposed allow electricity flow one way at at around 0.5 volts. it does that but it also is allowing electricity to flow backwards at 1.8 volts when it should be open line. . . . . . .

Ah, you are talking about the diode test function .... AH, okay, that reports in terms of volts (but is not the r/r putting out volts). Yes, Do THAT with diode check function with the r/r disconnected. Proceedure as Steve said.




About "seems like no power anywhere" :
If battery is good and well charged (volts at 12 point something), then you could disconnect the r/r, and check for "power everywhere". THis will prove to you that the r/r can not cause the "no power everywhere", well unless the battery is completly flat from not being charged, or the r/r is making a direct short to ground and in the process of melting down your wiring harness (which you havent said).
So, disconnect the r/r , charge the battery, and check again for "power everywhere".

When checking the charging system, first measure battery voltage with ignition off, then again with ignition on, then again at idle, then again at 4k rpm. Report here.

 

[bwringer]

The diode or resistance checks on many multimeters don't apply enough current and/or voltage to give a reliable indication of the diode's actual function.