78 KZ650 Recifier problem

Looks like my rectifier is blown. It's the type with 4 wires: two yellow from the stator, one black and yellow ground and a red/white output. If I test each yellow to ground on the rectifier, one yellow seems ok but the other is open (lots of ohms) in both directions.

I assume this is a single-phase alternator. It only has two wires coming out of the stator.

I do get over 60 volts AC between the two yellows coming out of the stator at 4000 RPM. At that rpm, with the rectifier connected, the batter reads 12 volts. Headlight is dim.

This thing has a rectifier/regulator. The dealer says it's not available but I can get one from Ebay for 130 bucks. What about making one? Is it a bridge rectifier together with a zener diode? Anyone have a design for one?

Post edited by: GaryG, at: 2007/07/19 15:04

Lou. He'd have a design I think.

GaryG wrote:

Looks like my rectifier is blown. It's the type with 4 wires: two yellow from the stator, one black and yellow ground and a red/white output. If I test each yellow to ground on the rectifier, one yellow seems ok but the other is open (lots of ohms) in both directions.

I assume this is a single-phase alternator. It only has two wires coming out of the stator.

I do get over 60 volts AC between the two yellows coming out of the stator at 4000 RPM. At that rpm, with the rectifier connected, the batter reads 12 volts. Headlight is dim.

Sounds like what I'm working with. It's single phase.
Have you actually load tested the battery? What does it show after a 90 second load?

It may have taken out the regulator.

I may be able to get you a good used regulator. I had a chance to swap one in for testing.

Another option I thought about. Back when I thought I might need one "someday."

Go to NAPA, and look at the small engine books. They have pictures of replacement parts.

I saw a PN 7-01695 voltage regulator. Rated at 10,13,14, & 16 amp. Listed at $74.99. Kind of looked like it might work, maybe.

Maybe someone with more guru than glue for expertise can follow up with this idea.

Or give plans for a build up.

:lol:

Found one from Z1enterprises for 84 bucks. Not in stock but they will have it to ship next Mon. or Tue.

Real helpful guy on the phone, too.

If you can find a circuit diagram, I would suggest making one. I made one for my 77 650 last week. It was worth it.

Yes, it's a single phase, regulator/rectifier combo with no dedicated "sense" line.

Here's the plans for the regulator portion:
www.geocities.com/loudgpz/GPZvRegMagnetField.html
This is a 3-phase version with a dedicated "sense" line, but it's basically the same thing. You'd leave off one of the phases, and tie a wire into a 12v source.

Here's the plans for the rectifier portion:
www.geocities.com/loudgpz/GPZdiy3phaseRectifier.html
It's also 3-phase, but just leave off one phase.

As you can see, it get's a little complicated and would be difficult to make it nice and small. It's also not dirt-cheap, and the SCR's are not Radio-Shack available. These types of reg/recs are plentiful and have many versions out there. They are also relatively cheap (under $100). Many bikes use the same type, but with just a different mount and connector. Single-phase models can often use a 3-phase model as a substitute. The addition of a "sense" wire is pretty trivial. Because of all these factors, it's just makes more sense to buy one than to make one. That's why I never fully built a working example.