Has anyone rewound a '77 KZ650 generator?

I did see any posts from others in the past, so I figure I'd ask.

The armature in my 77 KZ650 has some burned spots and measures 1 to 2 ohms higher than the upper limit in the FSM.
I'm also getting intermittent charging current. Performing the test in the FSM sometimes yields 3 amps at 4k rpm, but sometimes it only measures 1.5 amps. Same goes for the voltage, sometimes I get 14-15 volts at 4k, sometimes it doesn't go higher than 12V.

I just got the bike running again, so I haven't done any cold vs hot tests.
Tomorrow morning I'll try the FSM procedure from a cold start.

With rewinds costing about $150, and used/NOS units going for $250-500 I figure I could try my hand at rewinding the armature and maybe field coil. Has anyone successfully rewound their stator/armature/field coil/generator?

What country are you in? In the USA new stators are available for $75 - $150, other than OEM which is more of course.

Edit: on second thought, does that bike have one of those funky field coil thingies? All bets are off if that's the case.

I'm in the US.
Yea. It's the field coil model.

Can you convert to a standard type permanent magnet generator? If so, I'd do that. I'm not sure what's involved but engine covers and rotors are dime a dozen.

On a semi-related thought... If I had a bike with a permanent magnet (1980 KZ750G), for which dynamos are expensive and tough to locate, could I swap a 3-phase stator and flywheel? I know that would require a different R/R, but otherwise would there be a problem? The 3 phase are much more plentiful.

It will require some research. Supposedly, some of the Kz's with field coils can be swapped to permanent magnet alternators, but I know some can't, at least not easily. I thought the 650 was one that could be swapped with some alterations to the newer alternator cover.

Things to check:
Make sure the alternator cover for the two types can swap. Sometimes the bolt pattern is different (as on the Kz400). The cover holds the stator for the permanent magnet. Check the location of the locator pins... hollow pins that the bolts go through.
Make sure the crankshaft end is the same for both types. They need to have the same taper and length etc.

BTW, the field-coil type is more efficient. It only takes the horsepower that it needs, much like a car alternator. But it is more robust than a car alternator because it doesn't use brushes or slip rings. This meant that they could make it more powerful since it will handle a wider range of loads without wasting power. Usually I see these systems provide really good voltage even at idle.

The downside was that I believe it was more expensive to produce, and is a little more complicated.

The mechanical regulator is problematic if neglected. A solid-state replacement would be the way to go.

I see you've done some tests. Did you do the regulator bypass test? That's where you connect the brown wire to the green wire, where the regulator is located (and have the regulator out of the circuit).

rift.sawn wrote: On a semi-related thought... If I had a bike with a permanent magnet (1980 KZ750G), for which dynamos are expensive and tough to locate, could I swap a 3-phase stator and flywheel? I know that would require a different R/R, but otherwise would there be a problem? The 3 phase are much more plentiful.

This swap is much more common on the 650's with permanent magnets. It is electrically/magnetically feasible, but the big question is physical alignment and mounting. The later 650's and the 750-four have 3-phase, permanent-magnet stators that swap into the 1-phase, permanent-magnet, 650 motors easily.

This type of swap usually can use the same alternator cover.

I'm not sure on the 750 twins. Is there a 750 twin with a 3-phase stator for permanent magnet alternator's? You may have to just get it and see if the overall dimensions are the same for the 1-phase and 3-phase stators. What matters is the outside diameter, and the distance from the cover so it aligns into the rotor at the proper depth.