Hot Reg/Rec

[vintagemcyclegu]

I am working on a problem with my 80 XS1100SG. No charging voltage and no headlight. Field coil 3.5 ohms, stator coil 0.4 ohms. Reg/rec gets really hot is this normal?. Also headlight does not work. changed headlight relay and check inline diode OK. Checked all ground contacts all are fine.

[vintagemcyclegu]

Stator AC

How can I measure the AC coming from the stator.

[81xsproject]

Being that the reg-rec also triggers the headlight on these bikes and that you have no voltage, it very well could be the issue. Check the connections from the stator to the unit. Not only would it be a way to rule out the issure, but upgrading to a newer mosfet type unit will provide much higher and more stable charging voltage. You can find them on most new bikes 2007+ and some slightly older ones. The wiring is very universal (3 from the stator, 2 to the charging system). The trick for finding one is looking at the code stamped on the side. It should start with FH and not SH (ex FH001A). You have to redo the connector (I used the one off of my old unit) or wire it in directly. You can also buy a new Shindengen for something like 120. I have more info posted HERE.

[DAVINCI]

How can I measure the AC coming from the stator.

The reg/rec does not trigger the headlight, the stator does. IDK, man, the guy asks a simple question and you give him an electronic science project?

vintagemcyclegu; You need field coil current to generate voltage at the stator. You can check field coil operation by turning the key on, there should be magnetism at the alternator, enough to attract a feeler gauge or paper clip.

To answer your question, there is a connector behind the fuse box, three white wires. The ones that go downtown toward the alternator are the stator wires. Disconnect it and run the engine. Assuming you have field coil current, you should see 7-10 volts AC between each wire and ground. The voltage should rise with RPM's

[vintagemcyclegu]

I have another question

I measured the voltage on the plug that plugs into the Reg/rec from the main wire harness. Measuring the three white wires (which I assume is three phase AC voltge) was 11.1, 10.7 and 11.0 VAC. This tells me I have a bad Reg/Rec BUT why dosent my headlight work which gets gets its voltage from one of the white wires from the stator. The diode checks good and my tach works great. Very puzzeling. Thanks.

[bikerphil]

Relay might be toast, you could try unplugging it and jumping the red/yel and blu/blk wires and see if the headlight comes on with the key in the on position. The bike doesn't have to be running.

[DAVINCI]

Gee, is the bulb any good?

[skids]

The reg/rec does not trigger the headlight, the stator does. IDK, man, the guy asks a simple question and you give him an electronic science project? vintagemcyclegu; You need field coil current to generate voltage at the stator.

Well, actually the headlight is powered by the battery which is charged by the alternator, and the wire from the stator just switches on the relay. But your suggestion to check magnetic field is a quick and dirty check.

[81xsproject]

The reg/rec does not trigger the headlight, the stator does. IDK, man, the guy asks a simple question and you give him an electronic science project?

I like science

Well, educate me then. What are the 2 extra wires (green and brown) for that come off the OEM reg/rec?

[DAVINCI]

OK, I'll indulge you, but only because I think the hydraulic clutch mod is the **** Now as soon as I get the $ I'll tackle that

Brown = hot to field coil

Green = return from field coil.

The regulator controls the green-to-ground to adjust the alternator output

[vintagemcyclegu]

Problem solved

The problem was in the reg/rec. With the bike running I unpluged the reg/rec 5-pin plug (the one that comes from the stator) and my headlight came back on, so apparently the bad reg/rec was pulling down the stator voltage enough to affect the headlight. With a new reg/rec I will be on the road. Who has the best plug and play reg/reg around. Thanks.

[TopCatGr58]

See the For Sale Forum, the Parts/services by members sticky thread, scroll down to find GEEZER's REG/RECT unit, best you can buy, much stronger than OEM or generic, provides charging levels at much lower rpms!!

T.C.