'79 KZ400 charging

[Brendan W]

My son picked up a mint '79 KZ400 with 4000 on the clock. It's single phase charging and the original four wire r/r has been replaced with a five wire. Battery voltage at 5000 rpm rises slowly to 16V at which point I stopped the test becasue the rise was really slow. The shop manual says r/r is defective over 16V. My gut is to replace the r/r but what with and is it possible the wiring of the fifth ( sense wire ?) is causing the problem. Earthing is good. Drops on pos line to batt is 0.15 V and on the earth wire it's zero. Any tips appreciated. Apart from the r/r and the conversion to halogen headlight everything appears stock.

[Steve]

Not sure what the fifth wire would be, unless it is a sense wire, as you suspect.
Is it connected? If so, to what?

If you can release the fifth wire from whatever it's connected to, try touching it to both terminals of the battery while watching a voltmeter to see if anything changes.

What to replace it with? Not sure if the three-phase Polaris unit would work, but I don't see why it wouldn't. Posplayr might have some insight on that.

.

[posplayr]

Since it is a single phase alternator look for a compufire r/r off of a wrecked Harley. 99% are single phase. The only 3 phase are aftermarket. I have lifted them up for under $50 if not less.

http://www.ebay.com/itm/02-Big-Dog-Bulldog-COMPU-FIRE-REGULATOR-RECTIFIER-/191334572480?pt=Motorcycles_Parts_Accessories&hash=item2c8c6de1c0&vxp=mtr

http://www.ebay.com/itm/91-03-Harley-Sportster-Compu-Fire-Voltage-Regulator-91C-947-/221529113557?pt=Motorcycles_Parts_Accessories&hash=item33942a03d5&vxp=mtr

[Brendan W]

Thank you both, again, for you replies. I'll do a bit of research into these things and try Steve's suggestion.
I had forgotten how much fun a light twin is

[trippivot]

KZ 400 has a 3 phase AC dynamo -- but it has a electrically charged field coil - Which means you have to have a good battery to make power come out of it. There is a complete Kawasaki manual here at www.kz400.com start at page 154 for the overview of the system and read thru 160 which will show you how the brown wire has to be common for the regulator and rectifier.. CB 750 SOHC has this type of system also.

[Brendan W]

KZ 400 has a 3 phase AC dynamo -- but it has a electrically charged field coil - Which means you have to have a good battery to make power come out of it. There is a complete Kawasaki manual here at www.kz400.com start at page 154 for the overview of the system and read thru 160 which will show you how the brown wire has to be common for the regulator and rectifier.. CB 750 SOHC has this type of system also.

Thanks for the input but I'm lookig at p.220 of the '78-81 manual with a single phase permanent magnet set up. Not saying I don't have the earlier set up- been around old machines too long for that- but I only have two yellow wires from the alternator - so far anyway

[Brendan W]

Levelling off at 14.4V now. All I did was clean the R/R plug and poked a bit at the fifth wire where it disappears into the harness. Hopefully that's that for the moment.
She started misfiring badly and difficult to start. Primary coil resistance is 2 Ohms. Borrowed one from the GS and she fired straight up. ( 4.4 / 12.6 K).
Cleaning plugs, kill switches and so on as we go chipping away at the 1 volt drop to the coil. Happy days.
Plugs are very sooty. Don't know if it's the coil or the fact that it's fitted with 8s but 7s are specified. Would one step on the heat range make such a difference?