'78 kz1000 dim lights at high rpm

Hey everyone,

I have a '78 that has a bit of an electrical issue. I just purchased the bike, so bear with me as I'm still finding out everything about it (as in parts the PO added).

The issue right now is that at high RPMs the bike's lights fade away to the point where I shift early during night riding so I can see where I'm going. The dash lights practically turn off above 4000. When I really start to wind it up the bike feels like it loses power around 6000 rpm.

It has a set of dyna coils and a BUNCH of extra circuits that I'm still trying to sort out. I believe it has a relay supplying power to the coils, but have yet to confirm that by tracing the mess of wires in there.

As a bit of background, I just bought it and it is currently naturally aspirated, but it once had a turbo. I'm really excited about it. It is a 1075 8:1 with a falicon crank and APE studs/parts throughout.

Anyway, just wondering where I should start troubleshooting the issue. I plan to really dig into the problem tomorrow, but figured I'd ask for some pointers first.

Thanks,

Seth

get your multi meter

while running bike connect meter to battery and watch volts as you rev the bike.

On my bike.........my battery reads 12.8 volts at idle and at 4000 rpm it reads 13.8 to 14.2 volts.

this will show if the bikes stator is working and charging battery.

Possibly weak battery.

At higher rpm, the ignition may be consuming more of what a weak battery has to offer.

If not already done, would service the battery, charge it overnight at 1~2 amps, then have it load-tested.

Would also inspect and assure integrity of the ground connection where the battery negative cable attaches to the rear of the engine. The lug may be corroded or there may be corrosion between the lug and engine that's interfering with the ground connection.

Good Fortune!

Battery cables can sometimes get internal corrosion, reducing the current carrying capability. if they feel "Crunchy" when flexed, replace them. with larger (bigger diameter) cables. 6 AWG (American Wire Gauge) welding cable should be more than able to provide a good conductor.

4TheKZ1000 wrote: get your multi meter

while running bike connect meter to battery and watch volts as you rev the bike.

On my bike.........my battery reads 12.8 volts at idle and at 4000 rpm it reads 13.8 to 14.2 volts.

this will show if the bikes stator is working and charging battery.

+1 I would check it first. Sounds like your bike is not putting enough charge into the battery to keep it up and at high RPM's, the ignition load is eating up all the available juice and loading the system voltage down.

Just ran into that same problem on my 900.Found broken stator wire coming out of cover right at the rubber grommet very hard to see. Tug on each wire alittle not to hard though.Steve

Actually, when the engine is running the battery is a drain, not a supply. The charging system (R/R & stator) provides the power for the entire system when the engine is running. The charging system recharges the battery for the power it used while starting the bike, then the battery just sits there.
In your case, the charging system is not supplying enough power (power = voltage x current) to run all the electrical components, and the battery is being called into play, something it is not designed to do.
The 14.5 volts you see at the battery is not the battery voltage, it is the charging system voltage, which attaches to the battery to recharge it when it needs recharging.

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 reported to be 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. Also check from any of the three YELLOW wires to ground, this will show if arcing took place. Check only with the engine off !!

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, as it may gouge the case.

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.

Ok, new info.

Battery is charging right now for more testing tomorrow.

I found and fixed a few little issues that seem to have made the lights better. The problem seemed to be with the right side signal light ground washer. When i checked the 3 way female ground connector in the headlight bucket I noticed 2.88 volts vs ground. I pulled the ground pin out of the headlight connector and grounded it against a bolt into the frame. The lights instantly brightened up.

I tinkered with the nut holding that signal on and it caused the lights to flicker. I tightened it up and the lights are definitely brighter.

I'm thinking the bad ground was probably getting worse at high RPM due to vibration.

None of this explains my perceived loss of power at 6000 rpm, nor does it make any sense to me that a loose ground washer on a signal stalk could cause my ground circuit to be at a higher voltage than actual ground. Shouldn't the circuit have a ground strap to the to the frame or battery at some other point? Wouldn't those washers only be needed to ground the signal, not the entire circuit to the frame? Any ideas??

The BLACK with YELLOW striped wires, are part of your bikes ground circuit. A cable goes from the Negative(-) battery terminal, to an engine mounting bolt, check there for corrosion. All grounds must be clean and tight, for maximum current transfer. Sometimes, taking a M6 X 1 tap, to the holes that have a nut welded in the frame, will help the grounding problems.

Cleaning grounds is always a good idea on an old bike. DeoxIT D5 is also excellent for cleaning your connectors.
However, root cause of the losing power above 6k is your charging system. You will need to run through the procedure listed by MFolk. I prefer Ricks stators.