77 650 regulator

I have a solid state voltage regulator on my 77 650 and Im getting 16 volts @ 4000 rpm. My question is Ive got 7 ohms on the green wire to the regulator, could this be my problem? The manual says replace the rotor, any other checks I should do first? Thanks

Do you have a combined regulator/rectifier? If so follow this flowchart in our Filebase, maybe these tests will show something different.

Charging System Flowchart

Post edited by: OKC_Kent, at: 2006/11/05 17:20

I still have seperate reg /rec installed.

You have a solid-state regulator, but it's seperate from the rectifier?

Does the regulator still have 3 wires to it?
They should be brown, green, and black.
The green wire is to the field coil, and should have about 4 ohms to ground. If it was a lot higher, I would expect the battery voltage to be low. Having 7 ohms is not a big deal if you are able to get 16 volts at the battery, but there is a problem somewhere, because 16v is too high.
I don't know why the manual would suggest replacing the rotor, the rotor does not have any electrical contacts to the field coil on a 77 KZ 650. On that bike, the field coil is stationary and the rotor is just a magnetic-pole inverter. (Much better than the typical field coil setup with brushes.)

There are at least 3 possibilities.
1) The regulator is not fully grounded.
While running, measure the voltage on the regulator's black wire (relative to the battery's negative terminal). It should be close to zero volts within a few tenths of a volt.

2) The regulator is not getting full battery voltage on the brown wire.
While running, measure the voltage on the brown wire relative to the battery's POSITIVE terminal. The brown wire must have the same voltage (within a few tenths) as the battery's + terminal at all times while running. If it's lower than the battery terminal, the regulator will make the alternator put out more power. A good way to check is to put the meter's black lead on the brown wire, and the meter's red lead on the battery's + terminal. That reading should be almost zero volts all the time (while running). If it's more than a volt, you have a bad connection somewhere on the brown wire or the ignition switch or fuse box etc.

3) The regulator is bad.
If you perform the tests in #1 and #2, and the voltage tests pass, then the regulator is most likely bad. If it was the original regulator, I would say open it and adjust it, according to the manual.

Do your voltage tests using the battery terminals directly, not the frame etc.

Post edited by: loudhvx, at: 2006/11/05 22:48

loudhvx wrote:

I don't know why the manual would suggest replacing the rotor, the rotor does not have any electrical contacts to the field coil on a 77 KZ 650.

That one caught my eye too, here´s quoting the Clymer 650 manual on testing the field coil:

"... If the resistance shown is greater or no reading at all, the field coil has an open in it. If the resistance is less than indicated, it indicates a short. In either case the rotor should be replaced."

I believe it´s a typo/slip in the Clymer (not the first one either) and what they mean is that the
field coil should be replaced, not the rotor.

Btw, according to the manual you should see 2.7 - 3.4 ohms between the green wire and chassis with the wire disconnected from the regulator.

Post edited by: OnkelB, at: 2006/11/06 10:26

If your regulator is causing 16 VDC at 4K rpm, replace it asap! Tooooo much voltage will cause your light bulbs to pop if it goes much higher. The regulator is going bad. Shouldn't be much more than 14VDC at 4K rpm.

wiredgeorge wrote:

If your regulator is causing 16 VDC at 4K rpm, replace it asap! Tooooo much voltage will cause your light bulbs to pop if it goes much higher. The regulator is going bad. Shouldn't be much more than 14VDC at 4K rpm.

It doesn't have to be the regulator. It can also be the wiring to the regulator. A low voltage on the brown wire, or bad ground can cause this.

OnkelB wrote:

loudhvx wrote:

I don't know why the manual would suggest replacing the rotor, the rotor does not have any electrical contacts to the field coil on a 77 KZ 650.

That one caught my eye too, here´s quoting the Clymer 650 manual on testing the field coil:

"... If the resistance shown is greater or no reading at all, the field coil has an open in it. If the resistance is less than indicated, it indicates a short. In either case the rotor should be replaced."

I believe it´s a typo/slip in the Clymer (not the first one either) and what they mean is that the
field coil should be replaced, not the rotor.

Btw, according to the manual you should see 2.7 - 3.4 ohms between the green wire and chassis with the wire disconnected from the regulator.<br><br>Post edited by: OnkelB, at: 2006/11/06 10:26

Thanks OnkelB,
...should have known...Clymer.

Thanks for the numbers on the resistance too, I measured a good one around 4 ohms, but that included the wiring and bad connections etc. So, by the numbers, it looks like it should be around 3 ohms.

thanks for the replies, will check the voltage on the brown, the ground is good. Might try the stock regulator too, should the field coil be replaced with 7 ohms?

Going out on a limb here, but I wouldn´t worry too much about the field coil at this point, even if the reading does seem a little high - if you´re seeing 16 volts at the battery the field coil is working, if it weren´t you wouldn´t have any alternator output. Btw, you do measure the field coil with the green wire disconnected from the regulator, right?

I´d try the stock regulator first to see if it makes any difference in the charging voltage. You should see 14-15 V at the battery at high idle (1,600 rpms) with the lights off, raising the rpms you should see no raise in voltage if the regulator is working correctly. As Lou says, unlike the solid state regulator the stock regulator can be adjusted, the procedure is in the manual (pg. 155 if you have the Clymer manual).

Btw, apart from the high readings, are you having issues like bulbs popping or fuses blowing?

Post edited by: OnkelB, at: 2006/11/06 18:27

2 turn signal lamps blew, the bike had a fried harness when I got it and dont want this to happen again. Took a long break from it, still has a few other issues going on. The green was disconnected when I tested it.

I did the test that Loudvhx suggested, brown to positive a little over 1 volt. When I tested the black I get about a volt, also changed to stock regulator with no difference. Will this cause the problems Ive got?