Alternator Alternatives

[Bob Buehler]

Actually im about to pull the motor out of the 79 and put in the 82 so I can ger the FI turbo system and motor in something. So how have you been Jeff. Are you still able to ride.

[Bob Buehler]

Hold still Bob, I haven't posted about this yet as I am on the road, but your trouble does not likely lie in the regulator, more likely in the wiring connections. Take the red connector apart and look very closely at the wires and insulation. I'm going to bet they are starting to look toasty.

As J.R. explained it to me, there is a black signal wire that goes to the alternator, and if it senses less than 12 v it will signal the alt to go full field. As I learned, this alt is cable of putting out as much as 15.4 volts if asked, and if it does for long, it will toast your battery, and some wiring besides. Pop the cover to your alt, measure the voltage at the black wire, and compare it to the battery voltage. If it's 2 or so volts different, then that indicates some meaningful resistance somewhere in your wiring harness.

So my advice to you is don't waste your time troubleshooting your alt before you thoroughly inspect and renew the connections on your wiring harness.

I looked and there is a black wire in the block connector (female side on the wiring harness) but niether of the two wires comming out of the alternator are black. I will open it up and see what is inside the alternater.

[Jeff Bennetts]

The last time I saw you at the St. Clairsville rally my knee was causing me so much pain I couldn't concentrate, so my riding has been limited to around town. I bit the bullet and had a full knee replacement this Spring, hopefully I'll be back in the saddle next year and I'll put on another rally in Southern Ohio.

PM me your new contact info.

Sorry for the highjack, carry on.

[Bob Buehler]

Hold still Bob, I haven't posted about this yet as I am on the road, but your trouble does not likely lie in the regulator, more likely in the wiring connections. Take the red connector apart and look very closely at the wires and insulation. I'm going to bet they are starting to look toasty.

As J.R. explained it to me, there is a black signal wire that goes to the alternator, and if it senses less than 12 v it will signal the alt to go full field. As I learned, this alt is cable of putting out as much as 15.4 volts if asked, and if it does for long, it will toast your battery, and some wiring besides. Pop the cover to your alt, measure the voltage at the black wire, and compare it to the battery voltage. If it's 2 or so volts different, then that indicates some meaningful resistance somewhere in your wiring harness.

So my advice to you is don't waste your time troubleshooting your alt before you thoroughly inspect and renew the connections on your wiring harness.

So I checked the voltage at the black wire without the bike running but the ignition on and you get nothing. The red lead shows the battery voltage of 12.43.
Once you start the bike both the red and the black wires show 13 the 14 and once it got up to 15 when the rpms got up to maybe 2000.
So does this suggest the voltage regulator is faulty or could something else be wrong.

[NobleHops]

Sorry Bob. Was traveling.

Pop the cover on your Denso alternator. near the center of the plate you see with the cover off, there should be a single wire on a screw terminal. JR rewires these things, so I'm not 100% certain yours will be black, but it is on the ones J.R. does. Put the red lead on your multimeter on that, the black to a good ground like one of the rear engine hanger bolts. This is with the key on, bike not running. Note the voltage.

Next, measure the battery voltage, red multimeter lead to positive batt, black to neg or good ground.

If those two aren't very close, like .25V then you have excessive resistance in your wiring harness. In my case, there was in excess of 2V difference between the two and my alternator went full-field trying to charge what it saw as excessively low battery voltage, and it went into overdrive to as much as 15.4V and bad things did result (ask me about the battery I bought today).

Read some recent posts by KoolBiker (Aris H) on the tortuous route the ignition voltage has to take to make it to your coils, this is part of the trouble. Check and renew all of those connections if those measurements indicate a problem before you chase your tail elsewhere, then remeasure and see if you have remedied the problem.

Please report back what you discover.

N.

[Bob Buehler]

Thanks Nils, I pulled the cover late last night just to see what was under it. So I just checked the voltage and I got 11.78 across the battery and 11.70 on the black lead in the alternator. I think I must have drawn the battery down a bit last night starting the bike for the first time in several months. So I'm not seeing excessive voltage drop in the wires. I also checked the other lead (red and it showed 11.68 or something very close to the black lead.

This leads me to the next question of how to test the voltage regulator or adjust it.

[NobleHops]

OK then, that's a big variable accounted-for, that's good. I do not believe that can be adjusted, only replaced. When I was chasing my tail with mine J.R. sent me a known good regulator and I swapped it in which was fiddly but not hard. You're now out of my depth on troubleshooting at this point I'm afraid, but as you say, if it's sensing 11.78 at the regulator and the alternator output is not up in the 14.4 range or so measured across the battery terminals when the bike is at 2K RPM+, clearly the problem lies with the alternator or the regulator within.

[Bob Buehler]

So I think what you are saying is that I should probably just go ahead and order an new voltage regulator.

So the question is what year. I know it is a ZX9 alternator. I purchased it from James Elliot about 2004 maybe. I think Stephan was building them and James purchased a few to resell. I am going to guess it is a 2000 year alternator or there about.

Does anyone know how to determine what alternator it actually is.

[Bob Buehler]

Ok this is definitely not the route to take. I just spoke with a kawasaki dealer and they said a 1996 zx9 alternator was something like $900 and the voltage regulator alone was $325. There must be another way. Can I just put a resistor in line to drop the voltage coming out of it.

[daves79x]

You might take it to an independent alternator mechanic (we have a couple around here, you should be able to find one) and see what regulator might work, or if they can troubleshoot further. Might be just a bad diode.

Dave

[Bob Buehler]

That is definitely worth a try.

Hay dave can you PM Denis McCartney phone number if you have it.

[EMS]

Used Kawasaki alternators of that vintage can be had for around $50.-
Chances are that they are still in good working order. Only drawback is, they are not polished. For which you would have to invest in several pounds of elbow grease.

[Bob Buehler]

Some thing to think about. Called Tim's and got all the info I needed.

[Bob Buehler]

Just and update for anyone who needs the info in the future.

Tim's pointed out that it most likely is a zx7 alternator and he has seen one other produce the same problem. He had me call Rick Motorsports Electric with the Denso part number (21001-1115). Ricks had the voltage regulator (30-502 their part number?) for $75.

I took Daves advice and dropped it off at a local shop for more testing since I did not want to buy a part that I could not return.

I keep the thread update for anyone that might need help in the future.

[Bob Buehler]

The shop tells me the ZX7 alternator that I was using on my cbx has a rotor with a resistance of only 2.8 ohms and it should be 3.5-4.5 ohms and this is why my voltage regulator failed.

Apparently that rotor is not one that can easily be replaced or re wound so here we are thinking about shopping for a used one on ebay.

First, if anyone has one, I'll be happy to purchase it. Rather give my money to another cbx guy on here.

Second, the shop suggested looking at the aftermarket goldwing alternators since they appear to be very similar. He thought the cost was around $100. Has anyone seen this done.

What or why did we all start using the ZX7 and ZX9 alternators as the replacement units in the first place.