Tim's CBX alternator - way high output

[dcarver]

New Tim's CBX alternator is outputting 17-19 vdc on my 81 CBX. It's been back to Tim's twice for refurb.
The repair shop Tim's uses said to check voltage on black wire to ground. (Black wire from disconnected OEM regulator, 3 wires, black, green, red/white).


Voltage should be 4 - 9 volts, mine is 11.9, key on.


Per repair shop, if voltage on black wire is high, or voltage reversed, alternator output very well could be 19 vdc or so.
Looking at schematic, I don't see how voltage on the black wire could be anything substantially less than battery voltage. Maybe a bit less due to minimal losses, but not 4-9 vdc vs 12.7


Additionally, my understanding is field current is initially supplied by battery when engine isn't running. After start, output from the diode trio pack is fed back to the regulator, taking the battery out of circuit.

I would sure appreciate any feedback and advice. Even better if someone could take time and measure their black wire to ground, key on?
Complete write up here. https://candybuttorg.ipage.com/cba/node ... omment-910

I should add that Bill has been GREAT to work with, this is NOT a slam on Bill or Tim's CBX. Please don't read *any* negativity into this post, there is none. This is simply a technical issue that I'm learning about and a reach out for help.

Thank You, Don

[daves79x]

The black wire should have battery voltage at all times with the key on. Problems like this only make me more convinced to repair the stock alternator and go with that. Many guys run the conversions without problems, but both systems have their faults. At least you can repair anything wrong with the stock alternator. Sorry, I can't help you further.

Dave

[dcarver]

The black wire should have battery voltage at all times with the key on. Problems like this only make me more convinced to repair the stock alternator and go with that. Many guys run the conversions without problems, but both systems have their faults. At least you can repair anything wrong with the stock alternator. Sorry, I can't help you further.

Dave

Thanks for reply, Dave.

I called the alternator refurb shop and spoke to tech Jesus. They say it tested just fine on the bench with 4-9 vdc of field winding voltage. He also mentioned that he thinks the ZX7 alternator grounds via the case and not through the harness? I have to review my notes..

[CBX-tras]

The Tim's units don't have a dedicated ground like mine did. (green wire). Almost every conversion I've seen doesn't. Kawasaki didn't provide that since it attached directly to the case but, in the CBX it attaches to an adapter plate which attaches to the case. Another layer for the return path (ground) to make a 100% connection that it sometimes doesn't do.
If there's any resistance in any of the circuits, the voltage regulator will see that as a a need to provide more power.
De-pin every terminal in all of the alternator circuits and check for cleanliness and grip to the mating terminal.
Adding a dedicated ground would be highly recommended if you have the skills and materials.

[AshishNJ]

I am going add a ground to mine even though mine provides proper output.

[dcarver]

Alot of water undertake bridge since last post...

https://candybuttorg.ipage.com/cba/node/1034 for way too much info regarding Zx7r Nippon Denso alternator, Tim's CBX wiring harness, and factory wiring.

Summary
. Bench tested alt and it seems fine, using a higher speed drill motor for rpm
. Install on CBX, 17-19 vdc
. Alt is well grounded to battery ground, but ran external wire anyway
. Installed OEM and it works just fine, Thank You.
. Next step will be measuring resistance from CBX Red/White to Black wire with battery disconnected. Thinking that perhaps some high resistance in that circuit is 'tricking' the alternator into thinking battery volts are low, causing alt to output at max capacity.

Might have to wait a day or two...It's 105F outside...

[CBX-tras]

Any resistance in the "sensing" circuit will result in the alternator making more power. (It's the black wire in my photos above.) Check every connection to its source on the bike.

[NobleHops]

What JR said. I had a very similar condition with my Denso alternator, that JR provided, and it was a head scratcher at first. After much troubleshooting (with exemplary support from, JR I’d add) we determined that resistance in my wiring harness from a poor repair I had made was causing the alternator to go full-field as yours is, and that did in my case destroy the battery. A new wiring harness cured my ills. When we restored these bikes we ultrasonic cleaned and minutely inspected and tested the wiring harnesses, including the ignition switch contractor base and the kill switch path on the right handlebar switchpod, plus we frequently replaced the short harness from the 2-wire red connector back to the solenoid with new components and uprated wire, and an ATC fuse. Doing all of those things, with a rebuilt stock alternator, our bikes would charge the battery at idle, which very few CBXs can do without similar service. I will guess that doing the wiring harness service as described will probably cure your ills too.

[Larry Zimmer]

General note: In my years with cars and bikes electrical systems, the most common problem has been a poor ground somewhere. Not always the problem; BUT, the most common of problems. And, it doesn't take much. A good thought for all m/c charging systems is to check, once a year, your charging voltage at the battery. If it isn't in the 14.3 - 14.7 range, you might have a problem coming.

[NobleHops]

In this case, I’d just append your note to add, “at 2500 RPM after the bike is warmed up.” Best we’ve seen at idle after the full zoot service is about 13.5v.

[CBX1000FAN]

Very interesting... I had a similar issue last week. After checking as much as possible, I accidentally saw that one of the "male" pins (yellow wire) in the connecting plug from the alternator to the regulator is not all the way in - it was pushed back (maybe the connector is just old). I pushed it in - approximately 3mm with a long nose pliers and it seems I solved my issue. Regards.

[AshishNJ]

Did OP figure out the issue yet?

[AshishNJ]

Huh, my fingers are too fast, double posted :) . Learning from this thread, I added a ground to denso just like JR’s pictures.

[dcarver]

Did OP figure out the issue yet?

No, I have not. Put the rebuilt stock one back on and it's working fine... I imagine this winter I'll get back to the issue.

[dcarver]

https://candybuttorg.ipage.com/cba/node/1010
Here's everything I've tried so far..