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TOPIC: KZ 650 Electrical Troubleshooting - Help!

KZ 650 Electrical Troubleshooting - Help! 08 Jul 2020 09:26 #830094

  • Forrest
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My 77 KZ 650 B1 has been a great runner for the last 11 years that I have owned it. Except for this past year. Allow me to explain and some of you may have a solution or where to start:
- New Battery, fully charged.
- It would run for 20 miles or so then exhibit stumbling behavior almost as if it was running out of gas. It would then just cut out leaving me to coast dead stick. No electrical signs at all when turning the key.
- Trailered home and charged the battery.
- Went for another ride, and the bike exhibited the same behavior except in about 1/2 the distance, maybe 10 miles.
- Checked fuses, ok. Checked battery, still charged.
Do I have a ground issue or a bad voltage regulator or rectifier?
I could sure use some help! Thanks in advance.
KZ RIDER RELAY FLAG CARRIER #55
1977 KZ650B Ready & Fit to Roll Anywhere!
1974 F7 175 -first bike and still own
2002 ZRX1200R -Red the faster color
2011 Concours 14 -Now a Snarling Wolf in Sheep's Clothing!

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KZ 650 Electrical Troubleshooting - Help! 08 Jul 2020 09:54 #830095

  • F64
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Grab your meter

Ok a few tests.

meter on DC V

red meter probe on positive battery post(the post will be the metal part of the battery the cable attaches to)
black meter probe on negative battery post
Note voltage

Turn bike on
Note voltage

Raise rpm up to 4000rpm
Note voltage

shut bike off
81-KZ440-D2. Louis Dudzik's GM HEI ignition module converted 2015--no issues, Motogadget m-unit blue.

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KZ 650 Electrical Troubleshooting - Help! 08 Jul 2020 18:53 #830136

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Hi Forrest,
Just for reference, the 1977 charging system is different from all other Kz650 charging systems.
It uses a field coil without brushes. The field coil is stationary and bolted to the alternator cover with those three screws in a triangle pattern.
The flywheel is a magnetic-field inverter.
The regulator has three wires and controls the field coil in order to control the output of the alternator.
The rectifier is separate from the regulator and 5 wires, three of which are yellow or possibly white.
The stator is also stationary and is a big ring surrounding the flywheel. It is also mounted to the alternator cover.
The system performs better than the other years, but is complicated.
There are quite a few tests you can do with a voltmeter.

You will need a decent battery that is holding a charge.

After doing the voltage test F64 spelled out we can detail further tests.
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Last edit: by loudhvx.

KZ 650 Electrical Troubleshooting - Help! 08 Jul 2020 19:23 #830139

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Take a look in the Kawasaki Service Manual. It describes how to test the charging components, and if there's a charging system problem it should help you pinpoint it. If you find that the charging system is working fine at least you can eliminate it as a possible source of the problem. I had a problem with my 1977 KZ650-C1 and using the instructions in the manual I rather easily discovered I had a bad rectifier. I replaced it and the problem was totally solved. If you don't have a manual there is an electronic version for the 1977 KZ650 on KZRider. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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KZ 650 Electrical Troubleshooting - Help! 16 Jul 2020 16:00 #830831

  • Forrest
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Thanks guys! I will give it a go in the very near future.

P.S. Loud, You should grab Lawrence and some others, get out of the city, come out by me for a ride and cookout! I have some nice roads nearby.
KZ RIDER RELAY FLAG CARRIER #55
1977 KZ650B Ready & Fit to Roll Anywhere!
1974 F7 175 -first bike and still own
2002 ZRX1200R -Red the faster color
2011 Concours 14 -Now a Snarling Wolf in Sheep's Clothing!
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KZ 650 Electrical Troubleshooting - Help! 18 Jul 2020 09:55 #830922

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That sounds great. I think Lawrence was putting another Kz together.

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