These have virtually no heatsink, overheat and fail frequently, and are the reason this page exists. Symptoms range from over/undercharged battery, to refusal to start in hot weather, to various burned out parts. Replacement with a newer style 4 or 5-pin regulator is highly recommended.
OEM part number: 47X-81960-A2-00, 47X-81960-A3-00
Used on: FZR250, FZR400 (89-90 at least), FZR600 (89-94), many others
These have 5-pin connectors, and need to be converted.
Some of these have slanted pins (as in the photo), others you might need to grind down yourself, depending on your installation.
These have 4-pin connectors and same mounting holes, but bigger heatsink (see picture). You will need longer bolts to mount them, but no conversion needed otherwise.
Confirmed for FZR250, FZR400. Very likely to work fine with FZR600, too.
These are used on many different bikes, and you should be able to recognize it by just looking at the parts fiche and comparing with the photo (new one on top, old one below). Cost varies significantly between manufacturers, generally under $100.
Do NOT USE this upgrade VR (top in photo). IT WILL fail very quickly.
Your electrical components will be toast. Hopefully it will only KILL your bulbs. More than likely the inadequate VR WILL take out ALL of your electronics. It's a know FACT that an overcharging VRR can cost over $700 to repair & replace the burnt out electrical components.
Why spend around $70 for a (proven) unreliable VR?
Upgrade to a YZF/R6/R1 VRR @ all costs.
Please ignore the advice of replacing your faulty VVR with the one shown above (top in photo) Which is also fitted to 125cc motorcycles with FAR less electrical components!
There are several ways to use the new connector with the old wiring.
Use 14 AWG or thicker wire.
There should be no significant difference between horizontal/vertical mounting. If using the original bracket and plate, you will need M6x1.0-30mm bolts/screws (metric! - might not be available in regular US/Canadian hardware stores) and at least one regular washer and a lock washer.
The Voltage Regulator (referred to as the VR from now on) on pre-95 FZR600s has a reputation for crapping out and causing all kinds of stupid problems. I went through my entire fuel system and even overhauled the carbs, only to find out that the problem was actually my VR. For those not aware, the VR takes AC current generated by the stator and converts it to DC current that can be used to charge the battery and run the ignition and other electrical. This process causes the VR to generate a LOT of heat (you would probably be able to cook a steak on the VR by just letting the bike idle). The problem with the older style VR seems to be that it is not designed to properly dissipate heat and eventually it cooks itself. One solution to this problem is to replace the old style VR with a VR from a 95 or newer FZR600, YZF600, or R6. The VRs from these newer bikes use big honkin' heat sink that does a better job of moving heat away from the electronic bits of the VR.
Before you go ahead and drop some coin on a new VR and parts you may want to verify that the VR is indeed faulty. The following flow chart was put together by Naeslas and should allow you to verify that the VR is the problem and not some other part of the electrical system. I also recommend reading through this entire procedure before you start tearing into things so you have an understanding of what the process will involve.
Unfortunately this swap is not a bolt-on operation. The new VR is bigger than the old one (thanks to the big heatsink) and the plug is different (5-pin plug vs. the old 4-pin plug). Fortunately, the modifications required to use the new VR are pretty simple; I figured it out and I consider myself a mechanical moron. I completed this mod in an afternoon, which included more trips to the hardware store than I care to admit to.
Specialized tools are not needed for this mod; here is the list of what I used (as close as I can remember):
Here are the parts that I used, aside from the VR itself you should be able to get everything at your local hardware store (Home Depot and Ace for me).
BEFORE GOING ANY FURTHER, DISCONNECT YOUR BATTERY! WORKING ON YOUR BIKE MAY BE FUN, BUT IT SHOULDN'T BE ELECTRIFYING:!:
The first step of this mod is to locate and remove the old VR. The stock location of the VR is behind the left side rear fairing. There is one bolt securing the fairing and three penetration-style attachment points (not sure of the exact name, but this seems descriptive). You may need to loosen the two top bolts for the taillight surround (right behind passenger seat).
The VR is mounted to an aluminum plate near the rear (alongside the passenger seat). Disconnect the plug from the VR and remove the VR and mounting plate. Keep the mounting plate, you will be reusing it. Thoroughly pulverize the old VR with hammer, explosives, or whatever is handy. This step is very important because it will prevent the old VR from ever harming another fizzer.
The mounting plate for the VR attaches to a bracket that is welded to the subframe. I removed this bracket to allow more clearance for the new VR under the fairing and because one of the welds was already broken on my bike. I used the file and dremel (w/ grinding wheel attachement) to remove the remaining metal from the welds. I then used sandpaper to clean up the area where I would be remounting the plate directly to the subframe. This should ensure a better electrical ground. Note: removing the bracket will require that you drill the subframe to remount the plate. I should say here that I don't know how the subframe will be weakened by drilling two holes in it. It doesn't concern me too terribly; my gf doesn't like riding backpack on the FZR and she doesn't weight that much to begin with. If this makes you nervous you can probably can reuse the old bracket (you read this all before you tore off that bracket, right?). If you go that route, you will need to grind down some of the fins on the heatsink so they don't contact and damage the fairing when it's all put back together (see Yamaha_George's version of this mod for details on this).
Next you will want to modify the mounting plate. I chose to rotate the new VR 90 degrees CCW to the orientation of the old VR. The idea is that the fins of the heatsink on the new VR will be aligned horizontally to hopefully get better cooling from any airflow under the fairing. You will need to drill two holes (3/16”, may need to go slightly larger if bolts don't fit nicely) near the top of the plate where the plate will mount to the subframe. I believe I drilled 1/2” from the top of the plate so that it would sit flush with the top of the subframe. You will need to drill one 1/2” hole where the VR will mount to the plate. You can reuse one of the existing holes as the other mounting point for the VR, place the VR on the plate to mark out where to drill the three holes. Also mark out the area of the bottom section of the plate where the VR port will sit. Use a dremel w/ cutting wheel to remove this section (clean up with file as needed).
Once the plate is done, we will drill the holes in the subframe where the plate will bolt on. Position the plate where you would like it on the subframe and mark off where to drill. This should be approximately where the old plate was positioned.
Before we mount the VR to the plate, use aluminum foil to fill in the depression on the bottom side of the VR. This should help improve heat transfer between the VR and the mounting plate, using the plate as an additional heatsink. I used regular kitchen foil and folded up several sheets until I had filled the depression. If you can find an aluminum plate to fill this void it would probably work even better. Some people have used thermal paste (for CPU heatsinks) between surfaces here to further improve the heat transfer.
Now that everything is drilled we can mount the VR to the plate and the plate to the subframe. Use the 1/4” hardware to mount the VR to the plate in the following order (top to bottom): bolt, flat washer, VR, mounting plate, flat washer, lock washer, nut. Use the #10 (3/16”) hardware to mount the plate to the bike in the following order: bolt, flat washer, mounting plate, subframe, flat washer, lock washer, nut. Don't crank down on the frame bolts just yet, we'll be attaching the grounds to them momentarily.
Next we will hack off the old 4-pin wire harness. We will then lengthen the four wires so they will reach the VR port. The wire extensions should only need to be 6-8” to reach; with the VR mounted you should be able to guesstimate. Strip a bit of insulation off each end of the extension. At one end of each extension, crimp on a female quick disconnect. Use a butt splice at the other end to connect the extension to one of the four wires that were previously attached to the wiring harness (you will need to strip the wire ends here too). The three white wires are the AC feeds from the stator, the red wire is the positive lead to the rest of the bike. I used a fine point marker to label the insulator of each female disconnect to show what each plug is (A for AC wires, + for the red wire, - for the ground lead we will create next).
Next we will create a ground wire that will run from the VR ground terminal to the subframe bolt. You will need about 8” of wire for this lead; attach a female disconnect to one end and a ring terminal to the other. Remove the forward bolt attaching the plate to the subframe and add the ring terminal on the new lead and the ring terminal from the old VR (black wire located in the wire bundle with the red and three white wires). You can now tighten down the plate mounting bolts.
I recommend filling in the butt splices and and female disconnects with dielectric grease to minimize corrosion.
You can now connect the wires to the VR. The wires are connected as shown in the picture below; the order of the white wires does not matter. I used pliers to bend down the curlies on the connector so they would have a more secure connection to the VR.
I used some more dielectric grease around the Female disconnects to keep water and crap out. At this point you are basically done. Recheck the voltage on the battery with the bike running and you should see the voltage is now within tolerances. If everything is good, clean things up as desired with electrical tape and zip ties. The photos below show what my finished product look like.
A big thanks to everyone who helped me through getting my VR replaced. - Tommyj27