electrical issues with 1979 kz750 twin

I just got a 1979 kz750 twin, I am thinking B. I had power issues after I got the bike home. I found a dead cell in the battery. I replaced the battery and was able to start the bike and ride. I rode after work for four or five days. I only rode for maybe half hour tours. Then I was riding and the lights went dim, rough motor sound, and then died. I got the bike home and disconnected the battery. the next morning I jumped into the wiring. I found the ground wire to the back taillights was burned through. I replaced the wire and checked more wiring. I thought I found the problem. I rode with a friend to a metric bike meeting and the bike went down on me again coming back. Stalling out, and back firing. That scared my friend. I was barely able to get home. Today I pulled the whole wiring harness out, and went over all of it. I found more bare wires. I also took out any other wires that were not needed. The bike has, no starter I kick start, no blinkers not needed in Texas, key switch beside the speedo. Only what is needed. Also there is a janky fuse box, with one lead fused. The other two that go into there are spliced together.
I am thinking regulator, but not 100%. Looking for help. I have friend with a parts mecca. I am positive I can find something there. If there is any feedback that you would like to share, I would love to hear back. If there is any other info needed please ask.

The following is from MFolks, it is good advice and will identify most any imaginable problem if each step is performed in the order given. Few tools are needed and perhaps one of the most important is a factory shop manual. They are available from Kawasaki dealers, Fleabay Kraigslist, etc.

This is for four cylinder bikes, but varies in only a few details for twins.


Alternator Testing For the Older 4’s(Z1’s,Kz 900’s, Kz1000’s,Kz1100’s and GPz1100’s).

To check to see if the alternator is working you need to follow these simple steps:

1. Fully charge the battery as this will be the power source during this test.

2. Disconnect the Regulator/Rectifier at the plug that has the six wires in it.

3. Start the engine and let it warm to operating temperature.

4. If you're worried about overheating, position a large fan for cooling the engine.

5. After the engine has reached operating temperature, have a helper assist you, and using a multi-meter, read the output at the three yellow wires (or the alternator output wires)at the disconnected connector.

6. Raise the engine speed to 4000 rpm, and see what the three YELLOW wire combinations(or any alternator output wires) are(1-3,2-3 & 1-2). The output will be around 50 Volts A.C.(Alternating Current). BE CAREFUL, AS THERE IS A SHOCK HAZARD HERE!!

7. If any of the combinations are low or non-existent, the stator(wire windings) are bad and must be replaced.
Some of the older Z1’s and KZ900’s were phase sensitive, so check the wire colors carefully.

8. Using an OHMETER, Check the three wire combinations again, looking for a reading of 0.36 - 0.54 OHMS. If the readings are above or below, the stator may be bad and need replacement

9. Before ordering a new stator, check the connections from the stator as there are electrical "Bullet" connectors that may be damaged or dirty.
Inspect the wiring for signs of shorting or overheating too. www.z1enterprises.com sells replacement rubber grommets for the alternator output wiring, they get hard and could leak oil after a while.

10. Check the wiring coming out of the grommet as there have been situations where the wires were damaged causing a short(I.E. twisted together with insulation damage).

11. The sprocket cover will have to be removed to access the electrical connectors coming from the alternator, the left foot peg assembly and shifting lever will have to come off also.
__________________________________________________________
Alternator Stator Replacement On the Older 4’s
Source for replacement Stators

A. www.electrosport.com (They have a trouble shooting page)
B. www.customrewind.com
C. www.rmstator.com
D. www.ricksmotorsportselectrics.com
E. www.regulatorrectifier.com

1. If by testing either by checking the output voltage from the stator or by using and ohmmeter for resistance and the stator is determined to be bad, replacing the stator is not a difficult job.

2. The motorcycle owner should have on hand a replacement alternator gasket as it will tear on removal and leak if reused.

3. Put the bike on the center stand if possible and lean it to the right to minimize the oil volume that could come out when the alternator cover is removed.

4. Have selection of Metric wrenches and sockets along with Metric Allen keys to be able to accomplish this repair. ¼" and 3/8" ratchets and extensions may be needed along with Allen bits.

5. Remove the gear shift lever, the sprocket cover and possibly the left foot peg assembly.


6. A catch pan for what little oil will be lost should be positioned under the alternator on the left side. Newspapers will soak up any oil lost or some kitty litter will do as an absorbent.

7. Remove the alternator cover fasteners, some bikes use a socket head cap screw(Allen type) and others use the Phillips head type, the #3 screwdriver bit fits best for those. Use a small dish or can to collect the removed fasteners from the parts to prevent loss/damage.

8. The alternator stator is secured to the inside of the cover usually with three Allen headed bolts, Some bikes may have Torx style fasteners, Remove them and disconnect the three yellow wires that have bullet connectors on them from the bundled wires inside the sprocket cover.

9. If your bike has some color other than yellow for the alternator output wires, make note of what goes where as the older Kawasaki’s were phase sensitive in regard to the regulator/rectifiers.

10. When installing the replacement stator, clock or position the output wires and grommet so they fit into the small port under the alternator cover without being pinched or damaged.

11. Tighten the three Allen or Torx fasteners, securing the replacement stator to the cover. I like using the BLUE Loctite # 242 for hardware that can be removed with hand tools.

12. Remove the old gasket from the mating surfaces of the alternator cover and engine case by scraping with a piece of sharpened plastic like Lexan or Plexi-glass as these will not gouge the soft Aluminum
Cases. Avoid using a metal gasket scraper for this.

13. Position the alternator cover, checking for pinched wiring and install the fasteners with a little silver anti-seize on the threads, tightening to the correct torque.

14. Connect up the output wires to the mating female bullet connectors and while you’re in there, check the routing of the wire bundle that runs through there.

15. Inspect for signs of heat damage to the wire insulation and vibration damage too.

16. The side stand switch, neutral switch, and oil pressure switch wiring are all bundled with the alternator output wiring running above and behind the engine output sprocket. This bundle runs in a channel as it goes up toward the various electrical connections.

17. The regulator/rectifier plug on the 80’s bikes usually has six wires in it:

A. One (1)WHITE with RED stripe, this is the bikes main power wire usually 12 gauge in size.

B. One(1) smaller Brown wire, probably 18 gauge or so, the voltage sense wire for the regulator/rectifier, helps keeping it from overcharging the battery.

C. One(1) BLACK with YELLOW stripe wire, part of the ground circuits, maybe 16 gauge in size.

D. Three(3) YELLOW wires, maybe 14 gauge in size, the alternator output wires going to the regulator/rectifier which converts the Alternating Current(A.C.) to Direct Current(D.C.) using rectification, producing the power to run the motorcycle and charge the battery.

18. Reinstall the sprocket cover, again checking for pinched wires before tightening. Install the shifter on it’s splined shaft checking for proper location, and the left side foot peg assembly.

19. Except for the minor oil spill and reluctant fasteners, it’s not a very difficult job to do.

Happy to see my check out guides are popular!

I will pulling the case open in T-Minus 10 minutes. Thank you.

I figured I'd save you the trouble for once.

Every harness I ever pulled out of a bike had countless bare-spots and broken spots. The broken spots may still make contact so they are hard to find, but vibration etc make them open intermittently.

pioughdkz750 wrote:

I will pulling the case open in T-Minus 10 minutes. Thank you.

You will need to leave the case buttoned up until the first 10 steps have been done.

Kawasaki(and probably other bike makers) tend to have tape covered crimped splices inside the harness. Over time the adhesive will react causing corrosion.

On my 82 GPz1100 B2 I redid the FI harness using the tools,skills, and materials I gained from being in the USAF working on F-4 Phantom II's.

The Phantom has/had non insulated crimped splices used in the many and various aircraft relay boxes. After crimping the splice using a special tool, it's covered in heatshrink tubing and then heated with a high temperature heat gun.

This method has no adhesive to react to the splice, and for the most part is water and vibration resistant.

The closest I've seen for the type of work I do is a crimpable heat shrink splice like these:

Heat Shrink Butt Splices From Cable Organizers
www.cableorganizers.com
PART # WIRE GAUGE COLOR PACK QTY PRICE
NSPA-KS5-20 22-24 AWG CLEAR 50 $13.89
NSPA-KS5-16 18-20 AWG RED 50 $13.49
NSPA-KS5-14 14-16 AWG BLUE 50 $13.82
NSPA-KS5-10 10-12 AWG YELLOW 50 $16.48

For harness tape that's non stickey, try these websites:

Dry Vinyl Tape From Tape Brothers
www.tapebrothers.com

Dry Vinyl Tapes are non-adhesive plasticized polyvinyl chloride film tape. Easy unwinding characteristics - tape clings firmly to it’s own backing for tight wrap. High elongation and good strength to permit trouble-free binding of wiring harnesses for the automotive industry. Dry vinyl tape also used for plating applications- high stretch, good “cling” characteristics and great conformability provide for superior masking in hard chrome and other plating applications.

DVT-76B 2 in. x 250 ft. Black Dry Vinyl Tape
2 in. x 250 ft. Black Dry Vinyl Tape
Our Price: $6.54 Per Roll

www.wiringharness.com
• Non-Adhesive Vinyl Harness Tape, made to the original mil-thickness.
• Just wrap it tightly around the wires and knot the end.
• 100 foot roll is enough to do 3 to 4 harnesses complete.
• Available in three different widths, as original.
• Correct for all years (1955 to Present).

Part # Description Price
R0058272 3/4" Vinyl Harness Tape, 100 foot roll $12.00
R0058276 1" Vinyl Harness Tape, 100 foot roll $13.00
R0067108 1-1/4" Vinyl Harness Tape, 100 foot roll $15.00

I wasn't able to charge the battery just yet. I did want to get into the case though. I found that one of the chain stay brackets was broke. The top one. Then the wires looked ok going thru the housing. I will be charging the battery later, and getting more into the beast tomorrow. Thank you for all of the info. I am so excited about this bike. I like tearing into it, like a christmas gift. I also took a couple picks.