New regulator, stator tests good, but low charging voltage

[Guest]

My 82 GS1100E is not charging like it should. When I first start the bike and it is at a high idle it produces 13.3V. Once I idle it down to 1200-1400 rpm, it drops to 12.4 volts. I just put a new Compu-fire 40A regulator on it with both leads going directly to the battery terminals. Then I used a good weatherpack 3 pin connector to connect to the stator leads. I measure just 14 millivolts drop across the weatherpack connector on each pin so the connector is making good contact. I also checked for voltage drop on the 2 wires going to battery and no voltage drop is present. With the stator wires unplugged, I get 20V AC at idle and more than 80V AC revved up high. All 3 legs produce the same voltage. I did the test with one meter lead on ground and the other on each of the 3 stator leads while running and I got 0V AC on each stator wire. The stator wires ohm the same to each other and have infinity resiatance to ground. When I connect stator wires to Regulator, the AC voltage drops from 20V at idle to 10V at idle. So, I think I either have a weak stator or a weak rotor. I did notice there is a small crack on the very outer edge of one of the rotor magnets but all the magnets still have lots of magnetism. Any ideas or just roll the dice and pick one?

[posplayr]

Your battery is probably low which is pulling your numbers down. Do the Quick Test.

[Nessism]

Did you wire the stator directly into the R/R, bypassing the factory wiring? If not, this is first thing I'd do. Also understand that the charging voltage should be tested at 5000 rpm, not idle.

One other comment is that no load AC voltage tests on stators is not definitive. I had two different stators that made 75+ VAC but only pushed 13.7 VDC to the battery. Bit the bullet and got a new stator and charging voltage went up to 14.5 VDC like it should be.

[Paul.S]

I forgot to add I tested the battery with a nice electronic battery tester and it tests 100CCA over what it is rated at. I have also tried 3 different regulators. 2 brand new compu-fire units and 1 original new shunt-style unit. They all produce low voltage. And yes, all factory wiring and connectors have been replaced.

[Paul.S]

I think I found the problem. It appears my bike has the wrong rotor. All the pics on ebay of the correct part # rotor and the factory service manual show the rotor to have 6 rivets on the back. Mine has 9 and mine also has 4 seperate magnets. Im not sure as the pictures are blurry but it appears it might only have 1-2 magnets from the factory. So, I found a listing on Ebay for a NOS rotor and stator out of Finland (very expensive) and bought them. I will update once installed. 2018-04-22 14.51.18.jpg

[Paul.S]

Looks like I have a rotor for a GS1100ESD model but mine is the GS1100EZ model. Im sure it would work if it had a ESD stator but it is going back original so parts are not all mixed up.

[posplayr]

IIRC 83 ED has big end cranks and most 82 EZ are small end. If you had an 83 rotor on yours then your 82 is a rare one with big end crank.

If you just bought a 82 rotor it probably will not fit the big end crank.

The 83 rotors and 82 rotor magnet count is all the same.

CCA is not irrelevant but hard to deduce from that why your voltage is low.

[Paul.S]

IIRC 83 ED has big end cranks and most 82 EZ are small end. If you had an 83 rotor on yours then your 82 is a rare one with big end crank.

If you just bought a 82 rotor it probably will not fit the big end crank.

The 83 rotors and 82 rotor magnet count is all the same.

CCA is not irrelevant but hard to deduce from that why your voltage is low.

How can I tell if I have a big end crank? The crank has been welded/polished/balanced/shot peened at Falicon by previous owner so it might not be an 82 crank. I cant get the rotor off either until the rotor puller gets here later this week.

[Paul.S]

The prevoius owner did mention in the craiglist ad that the alternator shaft and bearing were upgraded when the crank was worked on at Falicon. So, I guess I do have that big end crank. And therefore the rotor would of course be different. Are the stators the same between the big end/small end cranks?

[posplayr]

If you go the electro sport you will see all 16v 750/1100 engines use the same stator do all the magnet counts on the Toyota are compatiable.

if you spent 5 min and did the Quick Tedt you would probably get your answer . It is in my signature.

[Paul.S]

I did some research and found the 9 rivet rotors are found solely on the big end cranks. The part # for the stator is also different when using the big end crank rotor vs the small end crank rotor. So I just ordered another NOS big end crank rotor and matching stator. Thanks for the info posplayr! Hopefully I can get the guy in Finland to cancel my prevoius order or I will have some parts to sell... Also, I read through your charging system quick test and I have pretty much covered what you have laid out in the test so my problem should be in the rotor or stator.

[posplayr]

I did some research and found the 9 rivet rotors are found solely on the big end cranks. The part # for the stator is also different when using the big end crank rotor vs the small end crank rotor. So I just ordered another NOS big end crank rotor and matching stator. Thanks for the info posplayr! Hopefully I can get the guy in Finland to cancel my prevoius order or I will have some parts to sell... Also, I read through your charging system quick test and I have pretty much covered what you have laid out in the test so my problem should be in the rotor or stator.

I doubt it.

[posplayr]

https://www.ebay.com/itm/Electrosport-Industries-Stator-ESG021/323218615214?epid=171210220&hash=item4b4154abae:g:REMAAOSwxupa2r3~&vxp=mtr

[Nessism]

The stator is same between 1982 and 1983, so that means what rotor is used won't matter.

From the parts fishe...

This Suzuki 31401-09300 STATOR fits the following models and components:

Suzuki Motorcycle 1982 GS1100ES GENERATOR (GS1100ESD)

Suzuki Motorcycle 1982 GS1100ES GENERATOR (GS1100EZ/ED)

Suzuki Motorcycle 1982 CRUISER - GS1100GL Generator

Suzuki Motorcycle 1982 GS1100E GENERATOR (GS1100ESD)

Suzuki Motorcycle 1982 CRUISER - GS1100G Generator

Suzuki Motorcycle 1982 GS1100E GENERATOR (GS1100EZ/ED)

Suzuki Motorcycle 1983 GS1100ES GENERATOR (GS1100EZ/ED)

Suzuki Motorcycle 1983 GS1100E GENERATOR (GS1100ESD)

Suzuki Motorcycle 1983 GS1100G Generator

Suzuki Motorcycle 1983 GS1100E GENERATOR (GS1100EZ/ED)

Suzuki Motorcycle 1983 GS1100ES GENERATOR (GS1100ESD)

Suzuki Motorcycle 1983 KATANA - GS1100GL Generator

Suzuki Motorcycle 1983 TURBO - XN85-D Generator

[Paul.S]

If you go to Suzukipartshouse.com and look at the exploded diagrams, they list 2 different rotors and 2 different stators for the 82-83 model 1100. They also list 2 different crankshaft ends where the rotor presses on. The rotor that has the 9 rivets is listed for the D model and the D model also has a different stator. The D model (big end crank) has rotor 31402-49330, and stator 31401-09300. The Z model (small end crank) has rotor 31402-49310, and stator 31401-49310.