Rectifier Mod, adding Heat Sink
 

Dear Fellow CBR owners,

I recently had an issue where my '93 CBR wouldn't start after work one day. I got a jump from someone, but saw that the bike wasn't charging correctly (I have an aftermarket voltmeter installed). I had to try and get home, but strongly suspected I wouldn't make it home. And I was right. About halfway home it stalled. I pushed it into an abandoned parking lot and called for my son to come rescue me. He arrived with jumper cables and we let the bike battery charge up for about 15 minutes. Got it started and got it home. I suspected the infamous Rectifier. I sniffed around the left side of the seat cowl...and sure enough...smelled that unmistakable smell of cooked electronics. So apart came everything to get to the Rectifier. It was indeed cooked, as was portions of the connector. Testing the Rectifier proved it was damaged. So I ordered a new one, but decided to modify things to keep the new Rectifier cooler. I purchased an inexpensive aluminum heat sink and some thermal paste. I cut a piece of the heat sink sized to match the Rectifier, and drilled matching holes in order to mount it under the Rectifier. I cleaned up the connector by scraping away the burned plastic from the individual connections. I generously covered the bottom of the Rectifier with a coat of thermal paste, and using .4" inch longer bolts attached the Rectifier to the heat sink and mounted the assembly to the bike in the original location. This mod should help keep the new Rectifier cooler. Total cost was around $22 for heat sink, thermal paste and 2 longer bolts. And there's plenty of room under the seat cowl for clearance.

https://cimg5.ibsrv.net/gimg/cbrforu...0bd9ad23bf.jpg
https://cimg6.ibsrv.net/gimg/cbrforu...30d2725cf8.jpg
https://cimg3.ibsrv.net/gimg/cbrforu...b6dec0bebe.jpg
https://cimg4.ibsrv.net/gimg/cbrforu...870f7047db.jpg

Great job, thanks for the heads up, I'm sure others will find it really useful 👍

These are also good:


https://cimg5.ibsrv.net/gimg/cbrforu...fb2869f818.jpg

From what I've read, this one provides more current to the battery than the original unit at low to moderate revs.

A word of caution...there's a huge amount of electrical current coming up those yellow wires from the alternator, and it's looking for any excuse to short itself and then burn itself!

Make sure your electrical connections in the junction box are absolutely perfect. Don't ask me how I know this!

Cheers,

Dennis

Thanks dmoh for the heads up.
I think one of our other members got one from there recently as well and seems to work well.