FZR400 charging system

teazer

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I dusted off the wife's FZR400 and fired it up and as I blipped the throttle the headlights got brighter and then less bright as the revs rose. So I grabbed a multimeter and checked and the battery had a loose ground lead, so I tightened that and got a charging reading of 15v and sometimes higher.

The R/R also got pretty hot all things considered. It's a little 4 terminal device with no ground lead. Just three alternator leads plus a charge the battery lead.

ebay has R/R from about 20 bucks but I an tired of buying garbage, so I'd like to get one that works. As it happens, I have a 5 wire from an 04 GSXR600 lying around here somewhere that I'd use if it works.

So before I burn the bike down, any reasons I shouldn't just rearrange the 4/5 wire connectors and fit the GSXR unit?
 
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teazer

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I removed the seat cowl to get at the R/R and as might have been expected, the 4 blade terminal is showing signs of overheating.

Replacing the connector is easy but I'd like to fit an R/R that's a few decades newer if possible. Any thoughts about the GSXR600 unit that's taking up drawer space?
 

teazer

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Ah well. So far so good. I had to change from the 4 pin (3 charge and one battery lead) to a 5 pin connector and wire in the ground connection but that was simple enough.

Fired the bike up and she settled down to 13.9-14.5 volts which is a lot closer to perfect than the 15-17volts a few hours ago.

Needless to say, the rear seat cowl didn't want to fit over the larger R/R, so that took a while to make the new bits and old bits play nice together.

Hopefully it will have cured the bike of the tendency to kill batteries every year or so. I'll check the voltage over the next few weeks to make sure it doesn't drain down.
 

irk miller

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The shunt regulator is burnt out, which is why it's overcharging and making the lights bright. It can't regulate power. Sounds like it may be installed in a location that doesn't get enough air. You may consider relocating it somewhere to get better air flow.
 

teazer

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Thanks Irk. Correct that the R/R is rooted, as they say in the land of Oz. The stock OEM design has no fins. Zero fins to dump heat and it's tucked under a seat cowl with not a lot of airflow. It also doesn't have a ground lead, it's internally grounded and from there to the frame through the mounting bolts.

I adapted the wiring loom and the GSXR r/r which has lots of fins and it seems to have fixed the problem. So far so good. Voltage is back where it should be and the R/R isn't getting hot and the connector is all new. I let it sit overnight and fired it up. Once it started voltage at idle was around 12.5 volts and it crept back up to 13.5 at idle over a couple of minutes as it charged the battery. at 3,000 -4,000 it settled down to around about 14.5, so that's all good.

Of course it's possible that the stator may have been damaged, so I'll check the resistance between coils to see if it's in spec.

Just as well I didn't fit a Lithium battery.......
 

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