Suzuki GS Stator Problems - Bad Design.

[chips99]

Hi,

I don't have stator problems and I know people do have
problems with the Stators on some bikes but I didn't
know Suzuki "To save expense in the regulation circuits
Suzuki decided not to regulate all three phase inputs (all
three wires coming from the stator), but only ONE"

Is this true?

I found the info below for the 1982 Katana but it list this
problems for most early 1980's suzuki Motorcycles on this
website:

http://www.electrosport.com

BRAND: SUZUKI
MODEL: GS1100S Katana (GSX1100 Katana) GS1000S GS750S
YEARS: 1982
CATEGORY: MOTORCYCLE

TECHNICAL ISSUE DETAILS

Suzuki's GS models all use a permanent magnet alternator
system for charging the battery. This system consists of
a stator with three output leads and a regulator/rectifier
which rectifies the stator AC output to DC and regulates
it to 14.4Vdc to charge the battery. Problem however is
that the way Suzuki handled the regulation on these bikes
is not very good. To save expense in the regulation circuits
Suzuki decided not to regulate all three phase inputs (all
three wires coming from the stator), but only ONE. One of
the three wires from the stator (YELLOW) feeds directly into
the rectifier circuit without ANY regulation. One of the
three stator wires (WHITE/BLUE) feeds into the rectifier
AND has a regulation circuit attached to it. The third
stator wire (WHITE/GREEN) feeds into into the bike wiring
harness, connects inside the headlight to the handlebar
switch and comes back from the handlebar switch as a
WHITE/RED wire which connects directly into the rectifier
bridge without ANY regulation. Inside the handlebar switch
the connection between WHITE/GREEN and WHITE/RED is made
when the lights are turned on (which is not an option on
US models, so the connection between these wires is continuous).

NOTE: the stator output is identical on all three wires. The
three different colors are not needed, it does not matter how
you hook up the stator wires as long as you hook them all up.
The result of this cost cutting is an unbalanced load on the
stator (the stator wants to see an equal load on all three phase
outputs) which causes premature stator failure. Our replacement
regulator/rectifier regulates on ALL THREE PHASE INPUTS. This
means that the load on the three phase outputs of the stator is
equal, greatly improving the system and its reliability. Our
ESR models for these Suzukis therefore have THREE YELLOW INPUTS.
And it does not matter which YELLOW wire connects to which stator
output wire. We recommend removing the loop through the wiring
harness and connect the WHITE/GREEN stator wire directly into
the regulator/rectifier. If you replace the OEM stator with
one of our ESG stators you will notice also that the output
leads of this new stator are all YELLOW. We also recommend
checking all electrical connections in these bikes. The
connectors are not that great, and the bikes are fairly old
by now. Clean the connectors one by one with some contact
cleaner and make sure the bullet style connectors are tight.
Our faultfinding chart: Fault Finding Guide will be a great
help in diagnosing when you have a charging problem on these
Suzukis.

[rustybronco]

Hi,

I don't have stator problems and I know people do have
problems with the Stators on some bikes but I didn't
know Suzuki "To save expense in the regulation circuits
Suzuki decided not to regulate all three phase inputs (all
three wires coming from the stator), but only ONE"

Is this true?

No it's not true.
on some models that have the ability to switch off the headlights, the headlight switch would disconnect ONE phase of the stator when the headlight was off, the two others would be up, running and regulated. the same when the headlight was on, except all THREE phases would be regulated.

[flyingace]

First of all, I don't think this is about the weakness of the stator, but of the R/R. I think they mean the design of the R/R rectifies the current OK, but the voltage regulation is only applied to one of the poles. This is not my understanding of how these things work. I thought the current was rectified first, then regulated on the way out.

Is there an electrical guru out there who can understand what Electrosport is saying?

[posplayr]

I did a quick read and I think they are referring to the number of SCR's that the R/R includes. Each SCR is basically a switch which directs current back to the stator instead of allowing it to flow to the GS charging system and battery. The SCR is controlled by a circuit that measures the voltage of the battery comparing it to an internal reference voltage and turning the SCR on (shorting) when the voltage is too high and opening it (allowing it to pass) when it is too low.

Some of the earlier R/R had this single SCR design. There are later units that used three SCR'sGS1100E's for example). It seemed to change year to year. The single SCR is more failure prone, because if all three stator winding are putting out too much current (due to high RPM), the single SCR shorts only one of the legs to make up for too much coming out of all three.

If there are more SCR's then the shorting of the stator legs is distributed across three and so each SCR is stressed less and the single stator leg that was being shorted is now stressed less because of equal distribution of the pain (across all legs) of shorting to stop the stator from outputting power.These SCR's operate on the same electrical power signal that the full wave rectified does.

The benefit of the FET based design is that it is also balanced, but in addition there are not voltage drops for both diodes and SCR which generates more heat in the R/R. On the downside the stator is stressed incrementally more because there is a larger voltage drop across the stator with FET (i.e. the FET it is a better short). This is only incremental and represents a perhaps an increase in power in the ratio of 1-(15-1.5)/(15-0.7) or a 5% increase. On the other hand power dissipation of the R/R might drop nearly in 1/2.

[reddirtrider]

I think Electrosport is playing word games and not being fully honest in describing the Suzuki R/R's. If they have a truely superior product, why the need to disseminate missinformation.

Let me add that I would be surprised indeed if their R/R wasn't better. After all, 30 years later if they couldn't they shouldn't be in business.