Rectifier gettng hot

I recently bought a 78 KZ1000, the previous owner parked the bike due to an unresolved electrical problem. The regulator would smoke and the blow the main fuse. I guess the fact that the regulator had a hole blown in the back of it didn't raise a flag to the previous owner. I replaced the regulator with one from another 77 KZ1000 I have. I also checked the terminals for continuity and verified the connections were good. Without the regulator I was getting DC volts as high as 13.8v - 14.6v. Now with a new battery and replaced regulator I'm getting 13.1v - 13.3v, but I noticed the rectifier gets pretty hot. To the touch it's too much, but so is the engine when running. So what's the norm for the rectifier alone temperature-wise?

Post edited by: vasnico, at: 2006/11/29 21:30

Post edited by: vasnico, at: 2006/11/29 21:31

on most motorcycles 13.8v is "normal" Cars run 13.8v also, 14v is what my 05 Jeep Cherokee runs @ anything above 2000rpm's, as far as the temp of the rectifier goes im not sure the normal temp but mine gets pretty warm also when i have a heavy load on the system ie: Lights on,heavy drain on the battery ect.

The KZ's with permanent magnet alternators work a little differently, the more load on the system the cooler the reg/rec will be.

The reg works by converting excess current into heat, so the less electrical power you are using, the hotter it gets.

The alternator puts out full power all the time, so the excess has to go somewhere

Aaah!
I did not know thatm well then I guess I'm in good shape, thanks for the help guys, Later....

What Steell said, but I'd like to add that the rectifier portion also gets hotter as you use more electrical power on the bike. So, even though the regulator portion generates less heat when you use more accessories, the reg/rec will never exactly get cold (probably cooler, but not cold).

Normally, the reg/rec will be hot enough after 20 minutes that you can't grab it, but you should be able to touch it.

Most KZ hit at least 14v, at the battery, with a sustained 3000 rpm. If you can never reach 14v, then you may still have some troubleshooting ahead of you, but we'll be here.

Post edited by: loudhvx, at: 2006/11/30 02:27

loudhvx, have you ever messed with using an aftermarket combination reg/rec on '77-'78 KZ1000? It seems to me that the three generator leads, ground and hot to battery, is all that a generic reg/rec would need. I mentioned that I have two KZ1000's and both are complete bikes. I parted the 77 to fix the 78, but now I feel like breathing life into the 77, but I took it's rectifier for the 78. I have a reg/rec from a Suzuki that has three yellow, one black/white, one red, leads and was wondering about crimping a connector to adapt it to the 77 KZ. What do you think?

Post edited by: vasnico, at: 2006/11/30 09:37

I believe that reg/rec units come in two varieties. The Kaw style uses a wire from the switched VDC source to tell the reg/rec what voltage is on the harness so the reg/rec can vary its output accordingly. The other type has a sensor on the output line for that feedback info... thus a Kaw reg/rec will have three yellow (AC in), black/yellow (ground), white/red (VDC out) and brown (this is the sense from wiring harness connection). The Suzuki lacks one wire so I would GUESS that the red wire is both the VDC out and the sense wire with the black/white being the ground and three yellows being VAC in but I would figure out what bike this reg/rec came from and look at a wiring diagram before installing on my bike. I have made assumptions before (I would assume red is hot and black/white is ground) but have been really wrong as non-Kaw companies may use very different wiring conventions. If the Suz reg/rec is wiring incorrectly you could end up smoking it.

vasnico wrote:

loudhvx, have you ever messed with using an aftermarket combination reg/rec on '77-'78 KZ1000? It seems to me that the three generator leads, ground and hot to battery, is all that a generic reg/rec would need. I mentioned that I have two KZ1000's and both are complete bikes. I parted the 77 to fix the 78, but now I feel like breathing life into the 77, but I took it's rectifier for the 78. I have a reg/rec from a Suzuki that has three yellow, one black/white, one red, leads and was wondering about crimping a connector to adapt it to the 77 KZ. What do you think?<br><br>Post edited by: vasnico, at: 2006/11/30 09:37

Never messed with aftermarket reg/recs, but they should be fine as long as they are for your application. You want to stay away from Honda electrics, and prefer Kawasaki or Suzuki if swapping other OEM stuff.

Here's what matters:
There are two major types of alternators common to most bikes. One uses a permanent magnet and the other uses an electro-magnet. Then they break down further to 1-phase or 3-phase. You need a reg/rec for a 3-phase, permanent-magnet alternator.

You can't tell, by looking at a device, if it's a 3-phase rectifier-only or a 3-phase reg/rec. The rectifier-only can have the same wires as a reg/rec. You need to make sure the Suzuki has a permanent magnet alternator (it's ususally the flywheel on the motor), and make sure there is not a seperate regulator and rectifier.

Then as WG mentioned, the 3-phase reg/recs can commonly have 5 or 6 wires (as can rectifier-only units). Your Suzuki unit has 5 wires so the wiring is pretty straight forward, as you guessed. I'd say it's worth a try. Put a decent volt-meter on the battery while firing it up. It should eventually hover around 14 to 14.5 volts, as you rev the motor. It shouldn't go any higher than that.