F650 Voltage Rectifier FAQ

compiled & edited by Kristian #562
by Kimon, Mark #403, Chris #782, Flash #412, November 2001
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 31 December 2006, by Winter #1935

For other related FAQs:


This FAQ is about the Voltage Rectifier or VR. If you were just looking for the VR Relocation FAQ, which helps the VR Keep Cool and helps stops it failing out in the first place, click the link to the VR Relocation FAQ. It's one of the hardest things to think of and one of the easiest (if not one of the more expensive) to fix.

Note: VR Problems on Fuel Injected Models
Problems related to the VR on Fuel Injected Models (GS, Dakar and CS) are not known (December 2006). Classic model bikes are more likely to experience problems with the VR. However just because you have a Fuel Injected bike, does not mean you will not encounter a failed VR.
Why does this not happen on the FI models? On the FI models, the VR was relocated to allow more effective cooling (down to the bottom right of the engine). The VR on the of the FI models is just plain better.
The Best Solution!

Okay, so you have worked out you need to fix your VR (either as a pre-emptive maintenance, or because your VR is stuffed). What solution should you use?

The best solution is to replace the Classic VR with a GS VR and relocate the VR. It may also be a good idea to replace your battery with an AGM battery too - especially if your last battery was fried by the VR.

The second best solution is to flay the VR. For this solution is is highly recommended you also replace the battery with a new AGM battery.

So What (Simply Explained) does The Voltage Rectifier do?

Well, it's actually shown as a combined voltage regulator and rectifier in the schematic. The bike has an alternator that puts out AC, and it always runs at full output. The VR converts that to DC, and bleeds off excess power to maintain constant voltage. (That's why it's always so darn hot.) As opposed to an alternator with a voltage regulator that controls exciter/field windings in the alternator.

Generally a generator produces for 1/2 the electric cycle while an alternator produces for the entire cycle. i.e. an alternator has electricity flowing "both ways" while a generator will only let electricity flow "one way" - since the production of this electricity is done in the same means (a stator/rotor of copper/magnets rotating within a cylinder of copper/magnets), the alternator is much more efficient since it is grabbing "all" of the electricity being produced (i.e. when the 'north' side of the magnet runs by a loop of copper, electricity flows in 1 direction, when the 'south' side of the magnet runs by a loop of copper, it flows in the opposite direction).

Since the systems within the bike run on DC, one of the jobs of the regulator is to transform AC to DC with a rectifier of some sort. The other would be to produce the constant 13.5-14 v. that we're all happy to see the alternator "producing."

It makes sense to me (but be warned, I'm somewhat feeble minded) that the alternator is producing more electricity at 5K rpm than it is at 1K rpm. The regulator is the device whose responsibility it is to make sure that we see a (relatively) constant voltage coming out of the alternator. In casual observation of my own voltmeter, it seems like I get about 13.0 volts out of the charging system when it's idling (and the battery is charged), and 13.5 volts when I'm running around with higher RPMs. Seacuke, #1214, F650GS, California,

There are two types of Alternator:

(1) The constant magnet. Here a magnet turns inside a set of charging coils. The output is rpm related, up to a max. When the output is more than what is "used" and the battery can "consume", the rest is shorted (to "earth" -the frame). A total waste of energy, but cheap to build. That is what the F650 has.

(2) The other alternator type has an electro magnet turning inside the charging coils. Here the charge is controlled by the "power" applied to the magnets. That is what all cars and some other bikes have. (All BMW boxers have this type)

Both of these generators need a rectifier to convert the AC to DC.

A generator also has electro magnets turning inside a set of charging coils but here the output is DC. This design was used at a time when rectifiers was expensive and unable to handle large outputs. The generator output is much more RPM dependent. The alternator can produce a lot more power at low rpm`s than a generator of the same physical size.
Haakon#626 (Norway,12-1999- F650GS)

The VOLTS available from our permanent magnet alternators don't go up with RPM, in fact, if you have lights on and a bunch of electric clothing hooked up, the voltage might even go DOWN at higher rpm. Why? Because the power demand that the IGNITION places on the system varies directly with rpm. Cheap to produce. (Great for the manufacturer.) Burns up VR's now and then. (That 's the customer's problem once the warranty period is up.) Flash#412

See also Electrical Misc FAQs - DC Electrical Basics, particularly for feedback on Power Draw

If you want some more detailed information see Electrex Site, which now has new tech info pages. We have the charging system described in Figure 1.

Here's a summary of Electrex information, chopped and edited from applying to VFR charging circuits to apply to us. Of special interest is paragraph 3 and 4, as to why some particular bikes are prone to failure. (Not good news I'm afraid.) The electrical troubleshooting chart on their page gives some expected outputs for the AC parts of the alternator coils.

Voltage Rectifier / Regulator Operation

This link s to a very nice schematic and theory of operation for the VR of a Suz*k* GS400E, which I believe is interchangeable with the one in the Classic (except for connectors).

Pay special attention to the last two paragraphs. THAT is why we have the VR flay. The flay essentially connects the "Monitor" input to the "Battery" output via a relay that is activated by the ignition switch. The reason is that the "monitor" input is returned via several connectors and contacts inside the ignition switch. This causes a voltage drop back at the VR which fools the VR into raising the output to an artifically high level (which then boils the battery).

I suppose if your VR fried and you're handy with a soldering iron, you could build your own replacement following this schematic. Flash 412 (CO)

VRF Regulator Rectifier Basics

Inside there is a six diode full wave rectifier, and every phase input can be switched to ground through a thyristor. The thyristors are switched by a regulator circuit that measures the DC output voltage. We call this a shunting regulator. It is a very simple system, and doesn't work very efficiently. But it does the job while not dissipating too much heat. That is why most OEM manufacturers still use this setup.

First of all the regulator relies on it's heatsink. That in itself is not bad , as long as there is good thermal contact between the diodes and thyristors inside the unit to the housing, and as long as there is a good airflow.

Quite often when a regulator/rectifier fails, a new one will fail after a fairly short time. It is a recurring problem (not on all bikes, but has been seen quite often). The stator has 18 poles, 6 per phase. Each pole has (I don't know exactly) about 20 turns of copper wire on it. Between the phase outputs of a delta wound system you will have 120 turns. Because of the hot spot in the engine, the copper winding's insulation starts to fail after some time. Most likely that will be somewhere from one layer of windings to the next layer on a pole. This usually happens only under load and when the unit is hot. Imagine a few of these shorts in between the phase outputs. You will have not 120 turns but say 50 or 60. The complete charging system will still be able to reach 14.4 V DC, it is rated for about 400W.

When you have a transformer with only a few thick windings, you will get a low voltage but higher current output. The same happens in the VFR Delta stator. Those 60 turns will give a much lower Vac but a much higher Iac. And diodes in regulator/rectifiers don't like high currents. If they are rated for 35 Amps, as most diodes are in this application, they can handle that whenever they get sufficient cooling.

When they run hot, the max current they can handle drops down quite a bit, which makes dissipate even more heat, and finally one of the diodes fails! Electrex stators are wound in star. The total power output is about the same as the original (lower Iac times higher Vac makes about the same... I know this is simplified, there is more to it....). But there are always two phases in between the phase connections. (=240 turns) The Vac is higher, and the Iac is lower. Even if there would be a short in between some layers of turns (I haven't seen that happen) you still wouldn't have the current output of the original stator, which is what destroys regulator diodes.

So far this is still unproven, but seems correct. It is difficult to prove, as you need to check the original stator for shorted windings whenever the systems is under load, and very hot. And it doesn't need to do it all the time even! Bikes that have had a few failing RR's stopped frying them after replacing the stator.

One last thing:

Problem #3:The output of the Voltage Regulator/Rectifier (VRR) is fed through the wiring loom and some sort of junction box to the battery. Make sure you have perfect connections here. I found a number of problems with voltage drops over these lines. Check the fault finding chart on http://www.electrexusa.com. It will guide you through the process. The best thing to do, if you see any voltage drops in between the VRR and battery (we are talking high current here, so any bad connection will give a significant voltage drop) is to feed the output of the VRR straight to the battery terminals using a (good quality) inline fuse.

Where is it and What does it look like?

On the Classic, It's located here under your seat, is a grey 2 x 2 square aluminium-looking device with a bunch of fins on top and a heap of wires coming out from underneath it.

MAKE SURE ALL THE WIRES ARE KEPT WELL AWAY FROM IT: WHY? It gets HOT. See the Electrical Misc FAQs - Tracing Problems Where the Fuse Blows all the Time.

Is there another name for this thing?

It is often (incorrectly) termed a Voltage Regulator which is partly true because it DOES regulate the Voltage, but also rectifies it. It's also actually shown as a combined voltage regulator and rectifier in the schematic. The bike has an alternator that puts out AC, and it always runs at full output. The VR converts that to DC, and bleeds off excess power to maintain constant voltage. (That's why it's always so hot.) As opposed to an alternator with a voltage regulator that controls exciter/field windings in the alternator. Flash aptly calls it a rectumfrier, because it gets so darn hot, which is why he suggests to move it. See the VR Relocation FAQ.

Failure and Testing

What are the symptoms of it failing?

So How do I test it?

  1. For Best Results, make sure the bike is good and hot. Don't check it cold. You will need a Voltmeter, which you can buy from your local electronics store.
  2. The Voltmeter photo shows a setting of 20V. Depending on your voltmeter, depends on if this is what you require. If you are unsure what setting to use, start at the highest setting, and work your way down (in this case 1000 volts, then 200 volts ...)
  3. Start the bike and make sure it is good and warmed up. Heat can affect your results, so make sure you measure the voltage not just once the bike is warmed up, but try measuring it after 30 minutes of riding if you can.
  4. Either attach the probes to the battery, or get a helper to hold the voltmeter probes to the battery.
  5. Rev the engine to 3000-4000RPM.
  6. The voltmeter should read about 13.8 to 14.5V
Volts @ 3-4K RPM Test Outcome
Less than 12.0V VR is dead - under charging
Less than 13.8V VR probably dead - under charging
Between 13.8V and 15.0V VR most likely okay
Above 15.0V VR most likely dying or dead
Above 17.0V VR is dead

Normal VR Test Results

Rider Bike Off @ Idle Few mins @ Idle > 2500rpm Comments
Ike647 12.1V 13.0V @ 1100 14.1V @ 1100 Rises to 15.0V @ 2500
Drops to 14.1V after 45secs
Bike sitting for 5 days
Chris #782 12.6V 14.4V @ 1700 14.75V @ 1250
14.96V (with lights)
14.50V (lights+horn)
13.80V @ 3000
14.85V (lights) @ 4000+
New battery, freshly trickle charged
Harl #380 ? ? ? 14.18V @ 3000
14.34V (no headlight globe)
14.34V (headlight pluged in)
14.18V after stopping motor
Colorado Bob #1297 12.98V ? Idle Speed: 1500 15.5V (fan on)
15.13V (fan+high beams)
14.93V (high beams)
RPM: 3200
15.02V (fan+high beams+brakes)
14.9V (fan+brake lights)
14.88V (fan+low grips)
14.95V (fan+high grips)
14.58V (low grips)
14.6V (high grips)
Engine warm to start
14.5V dropping to 13.3V within
5mins after turning bike off
Kristian #562 12.37V 12.13V (no headlight) 13.56V @ 1550 14.20V @ 2mins
14.62V (lights on)
14.19V @ 2000
14.25V @ 2500
14.26V @ 3000
14.30V @ 3500
14.33V @ 4000
Bike sitting at work for 4 hours
Drops to ~9.00V when starting
Fan came on @ 2500 due to heat
Kristian #562
(2000 model GS)
12.72V ? ~13.60V 14.08V @ 2500
14.09V @ 3000
14.07V @ 3500
14.06V @ 4000
14.06V @ 4500
Todd #389 Comments

Just comments for future reference: I've been riding around with the VR completely disconnected, both plugs, just on battery power on my slightly injured battery.

After charging it fully, and making a start (bike always starts as fast as I can remove my finger from the button), the voltage is remarkably steady.

The CDI must use considerably less than 1 amp.

Running the bike for 1.5 hours my load voltage with ignition running (with bike running) only dropped from 12.5 to 12.3 volts. (No headlight and only a few minutes with running lights (I have the Euro switch), modest brake light use, and a couple of minutes of radiator fan use.)

After stopping the bike and restarting it 4 times, the battery was recovering while running and the voltage was above 12.2 volts and rising.
Still get the same (acceptable) test readings (both BMW and Electrex test specs) off the stator, even when tested quite hot.
The voltage was quite steady as long as the radiator fan (or headlight, running lights) wasn't on.

The fan is a serious drain. Not sure what voltage the CDI quits at, maybe 11.2-11.5 volts?, but if you were running on the open highway, you could run a long time, maybe all day and charge at night.
Obviously this experiment does not apply to the FI or ABS models.
Sure makes it hard to tear it apart for rewiring when it still runs so well - except in traffic (it's like 95 degrees here every day).

Mark #403 Comments

If what is being said is true, about 14.8 vs. 15.3, maybe that's why some people are having to add water a lot, and others, like me almost never have to add water.

My regulator runs at about 14.3v most of the time, can jump up to 14.8. but never sees 15v. maybe there's a quality control problem with the rectumfiers.
I did confirm what someone else said. A GPS reads about 0.4V lower than correct. It was explained as being due to the diode, but I don't know what the hell that means...nonetheless, I confirmed it.

The voltage meter reads higher. also, the Garmin III+ is somewhat inaccurate, in that it isn't consistently 0.4V under, but floats between 0.3-0.5V under.

Kristian #562 - '00 GS Comments

Used my own patented in-the-FAQ-already Middle Section Faux-Tank off procedure. Took some photos for proof. You owe me a few beers.

I found the info on the accuracy of my Digital Multimeter. For DC Voltage it is: +-(0.5% of rdg + 2 digits). And it reads in hundredths. So, if it read 15 volts, then it could actually be from 14.95 to 15.09 if my math is correct. 1999 BMW F650-SE.

Why does the voltage creep up after first starting?

Is a high AC voltage good for the bike?

So what does turn 80 volts/whatever into 14.5 volts/whatever, if it is not the Voltage Regulator/Rectifier?

Fixing the VR

Is there an aftermarket source for this Rectifier?

by HsN

Our VR problems are no worse than most (Nippondenso VR equipped) bikes. So of course there must be aftermarket RR's available, which there is. Note that this ours is a COMPLETELY different system than the R and K bikes. On the Honda VFR sites, the VR failure is common enough that one of the sites has a remarkably thorough survey form at: http://www.troutman.org/vfr/rrsurvey/ and the best summary of Honda VFR VR problems, much of which applies to the F650 can be found here: http://www.yft.org/tex_vfr/tech/rr-maintenance.htm.

I think most of the internals of most of the (3 phase permanent magnet) VR's are similar, it's just a matter of a few details, like the capacity (amperage) and the connector plugs. (Obviously, there's a GREAT difference between the positive green voltage sensing wire of the OEM Classic VR and the negative green wires of the of the GS VR. As in Bzap!) At one time I would have believed it was mostly the connectors, but now that I realize the Electrex doesn't come with any, that's a moot point.


SX Electronics

I found that these guys in Greece actually make a Regulator for the F650, the "SX7 80" for 80 Euros.

They use the same regulator on the:

However none of the Hondas, including the CB400 Four, use the SZ7 Model.

I suspect that most of the time when the websites say "minor modification is required" they are talking about changing connector plugs. An interesting comment clipped from the SXelectronics.gr website:

According to the widely adopted design of similar products, the alternator works always in full power so the engine has always the load of the full powered alternator. The regulator rectifier we manufacture, operates in such a way that only the current needs of power are loading the alternator, so there is no extra power drawn from the engine. Other benefits our products offer, are the low operating temperature of the regulator rectifier and a small increase in the power of the engine.

My comment - this sounds interesting, a VR with a different internal design. I believe our regulator is the shunt type - always on full, bleeding power off as needed to a resistor where it dissipates as heat. As opposed to a switching VR (the SXelectronics type), where the VR just switches off the power when it's not needed. (If the VR switches off the alternator input to the rectifier wouldn't it run MUCH cooler than if it switches off the rectifier output (DC) into the VR?). Either way, the circuitry is more complex than in the OEM VR. HsN

Off Another Bike?

In a 2002 Sprockets Chris & Erin Ratay wrote: "FYI: We confirmed we can use a regulator from a Honda CB400 -- it is exactly the same shape, with mounting holes in exactly the same places, and 6 wires. Price for BMW part here is probably around $125, the Honda part is US$55. The only diff is the color of wiring - 4 wires are the same: 3 yellow, 1 red-white; for use on BMW, need to swap positions of the brown (earth) and green wires - Honda uses green for earth."

Note that Erin & Chris did NOT actually change to that regulator. Their problem lay elsewhere.

I did some research on this subject because you have to ask the question "Well, the wiring, VR size etc may all look OK from the outside, but is what is inside the VR up to the 280W output of the F650 alternator? So, you have to check the Capacity of the Charging System of the bike it comes off

Here's the results of that Search, in the CB400 Rectifier FAQ.

Has anyone actually USED another VR or Stator?


Hombre sin Nombre has. Here's what he's go to say about it:

After installing $307 dollars of Electrex parts, I had the joy of noticing the dreaded dashboard cluster crack. There's a crack starting in the lens of the idiot light cluster, bottom right hand corner. It continues into (and is probably caused by) a larger crack in the black plastic dashboard itself. POS is 3 months out of warranty, and I keep the bike inside the house, rarely park in direct sun, never splashed it with gas. Check out the bottom right corner of your idiot lights and the nearby dash with a light you can hold at an angle.

Continual problems like this (and the receding valves) make me consider finding a different bike, one that I might keep longer and have fewer problems with, but that I might find parts for 10 years from now. I have no idea what bike that might be. Right now there are few bikes that suit my purpose and interest me, and even fewer locally available choices.

I figure I'd share a couple late comments FYI that might be of interest on the Electrex stuff - I have not yet energized it, tho' I hope to tomorrow. I have a fairly complete chart of test values on the new VR if you want me to work it up into something readable sometime. (Also from a KLR Test Manual, with an alternator and VR similar to ours.)

Electrex isn't in any hurry to ship anything, they didn't Insure, and they don't pack except to throw it loose in a cardboard box. For the price, at first glance I was disappointed in the products. The connection wires on both units seemed of poor quality, certainly no better than OEM. (While unmarked as such, turns out they might actually have 105C rated insulation.) Both bags are marked "Made in Europe".

The stator was discoloured with a slight patina of rust, despite being in a heat sealed bag. It also showed evidence of having been dropped several times, with several impact cracks in the (thin with lot's of pinholes) epoxy coating on the coils and chips in the epoxy and varnish covering the laminated plates of the ferrous core. Not nearly as good looking (wraps, epoxy, and insulation) as OEM - looks like another product of Bulgaria.

Sloppily made, it's hard to push into place. I did my prep to the bolt holes, flattened most of the large lumps of varnish on the mating surface, and pulled it into place with it's mounting bolts. (Then removed the bolts and did the Loctite and torque thing.) You'll have to shorten the woven insulation sheath without nicking the wires, and the wires themselves are a foot shorter than OEM - no slack in the new installation. But they do include some plastic sheathing, and a new plastic plug and not too horrible brass terminals in order to match the plug in the bikes harness. The stator was within 2 bags. The inner one had it's tag cut off - the remnant says ..."within the EEC." But the good news is that the outer bag for the G07 stator lists: Honda VT500 Ascot, VT600 Shadow, VLX600 and Yamaha XV535 Virago, XZ550, XV700/750 TDM850, XV1000 Virago, XV1100 (no F650 listed). So it would suggest that with a little attention to detail, stators from these bikes should fit our Rotax, as might their voltage regulators. The Electrex stator might be one gauge lighter wire than the OEM - assuming more windings per coil, that might indicate higher output voltage, with lower amperage.

The VR comes with bare wires and no terminals - I guess they figure by the time you're looking at saving 20% off OEM prices you've long since burned off your original terminals and have installed your own, so you can solder on whatever to match. It has no markings on the bag except BMW F650 1997-00. Note that it doesn't say 1993-96? Maybe it was packaged for the USA. It's similar in size, heavier fins, but the cross section for the bolt holes is thicker, so longer bolts than the OEM bolts are needed to mount it. Otherwise, it will mount in the same holes as OEM. Between the bolt holes and the terminals, some prep needs to take place before it can be installed on the side of the highway.

The Stator wires are unfortunately a foot shorter than OEM - no slack in the new installation. But it's just long enough, if you route it touching the carburettor bowl (a big no-no for wires running 75 volts that have a tendency to melt) and shift the entire wiring harness forward 2-3 inches. And I have slightly longer (1-2")harness wires to the plug, since I replaced all mine when I burnt the first VR. Little did I know that I'd later wish for 6" of slack. The alternator plug used to sit on top of my battery - now it sits underneath and in front of the battery vent - not the best place for open plugs. And speaking of plugs, the plastic plug was not the exact mate to the other OEM plug. Easily adaptable.

Sure hope it gives me lower voltages!

Don't be in any hurry to buy Electrex stuff - after only being installed a month/800 miles, while sitting in traffic, the Electrex VR overheated and exploded, coating the seat/fender/burp tank and intake snorkel with burnt epoxy, melted rubber lava, and oily slag. (At this point, the bike lost it's ability to idle also - might just have been low voltage.) Never had one fail that badly before. At least it didn't melt the side cover or burp tank. I haven't done any diagnostics yet, as it took me 2 hours to dissemble and clean the mess enough to bring it inside, as the burnt stench is too sickening to have on the porch. (I don't mind the mess, but the stench is nasty, and it sprayed and dripped everywhere.)

Because of the 4 hour time difference, I was able to call Electrex. They have no idea how to handle a warranty claim, suggesting that I might mail it back, and they'll examine it, but maybe I should talk to their head technician (Ritzo) who wasn't available, and who did not return my call in 4 hours. No hurry, because they have no more VR's in stock, on backorder with unknown delivery date. ("Business is so good, we just cannot keep inventory in stock, it goes out as fast as it comes in, but we'll put you on the list for later if we get some.") Looks like AT LEAST another 3 weeks, IF I'm really lucky.

This will mean that for 2002 my bike will have been down 3 full months waiting for parts. My next bike will be JAPANESE. Might not have style, but at least it will run. I've had 2 strokes that were more reliable.

When the VR first blew, while stopped in traffic, all I noticed was that the bike started to smell funny. After a few minutes, I lost my idle, it dropped to about 900rpm, but the bike ran fine and restarted OK. At first I thought that I had blown a head gasket, and was burning coolant/antifreeze. But the coolant and oil are OK, and I discovered the VR mess. Then I figured the idle changed because I was riding on a dying battery, badly discharged by riding with a dead VR. But today while testing, with the VR removed, battery full charged, bike starts right up, but the idle is still way too low. Nothing in the air cleaner, plug caps and coils have proper resistance. I'm digging thru things but I'm clueless why the VR incident would affect the idle. I'm finding no wiring problems, no loose connectors or battery terminals. The idle has always been very constant - I've only adjusted it once in the last 15k miles. I was riding without a VR for a couple weeks, 200-300 miles, a while back, and that had no effect on the idle whatsoever, nor would I expect it to.

Can I use a GS Voltage Regulator on the Classic?

GS VR - The Size of it

GS VR - The GS Wiring:

On The GS VR:

GS VR ON the bike

Haakon#626 having now checked, the Output wires from the VR are :

GS VR - Post Installation

GS VR Installation

Instructions and images by PhilMills, more photos taken from other conversions.

This writeup covers replacing the OEM voltage rectifier on the F650 "Classic" with a voltage rectifier from a 2000-or-later F650GS and relocating the VR outside of the seat pan. The final result will look like this.

Parts Required


NOTE: The molex pins and pin tool can be readily located at Radio Shack (or similar stores). Example: 4 pins, plus a connector to throw away later.

A. Removing the Original VR

  1. Remove seat and left- and right-side panels from the motorcycle.
  2. Disconnect the battery - both positive and negative terminals. If your VR has failed, then it's very likely to have damaged/destroyed your battery in the process, so this is a good time to check and possibly replace your battery with a "maintenance free" one (see the BATTERY FAQ).
  3. Locate the VR under the seat. Remove the two bolts holding it down. Save the washers for use later.
  4. The VR is connected to the rest of the motorcycle in 3 places - detach them: - Grounding cable to the frame - Connector with 3 yellow wires (goes to generator/alternator) - 2-pin connector that eventually leads to the battery
  5. Remove the old VR from the bike.
  6. We will reuse the yellow-wired connector attached to the VR: this is a 4-pin connector with only 3 of the pins in use. Mark the connector to indicate which of the 4 pins is empty. Use the pin tool to pop the pins free from the connector. Retain the connector shell, discard the old VR.

"VR" for the remainder of this writeup will refer to the F650GS voltage rectifier.

B. Prepping the new VR

  1. Use the razor knife and a lot of care to remove the black wrapping and electrical tape from the wire bundle. The GS rectifier has 3 yellow wires going to one connector, and two each of red and green going to a second connector.
  2. Cut off the OEM connectors - leave as much wire as possible on the red and green wires, leave 6" of the yellow wires. No source has been found for the mating ends of these connectors, so they aren't useful for this job. Strip 1/2" of insulation off of the ends of the bare wires.
  3. With the 3 yellow wires:
    1. Crimp on the molex pins. Use some solder to keep them in place and ensure a good connection.
    2. Insert the pins into the connector from the old VR making sure to leave the originally-empty pin empty.
    3. Tape these wires together for neatness.
  4. With the 2 red wires from the VR:
    1. Use the crimp connectors to attach a length of red ignition coil wire to each of these wires (we need to extend them to reach the battery from the VR's new location).
    2. Take one of the ring terminals and connect it to both of these extended wires (both red wires into the same ring terminal).
    3. Tape these wires together for neatness.
  5. With the 2 green wires from the VR - repeat the procedure for the red wires, but use the green ignition coil wire lengths.
  6. Coat the wire connections and entry into the ring terminals with liquid electrical tape to waterproof them.

By this point, the new VR should have:

Now we will prepare the motorcycle for relocating the VR - the new location will be outside of the seat pan, adjacent to the coolant overflow tank for the radiator.

C. Removing the snorkel

  1. Loosen all visible/reachable bolts that hold the airbox top and bottom halves together.
  2. You should be able to seperate the airbox halves enough to easily remove the snorkel from the airbox.

At this point you must decide whether you'd like to modify or completely eliminate the snorkel from the airbox. If you eliminate the snorkel, you will need to drop the needles in the carberator by one notch. Modifying it will not require any carb modification that I am aware of.

D. Modifying/replacing the snorkel

  1. Take the razor knife and cut away the outer two "ribs" from the snorkel - this will reduce its overall length by roughly 2".
  2. Replace the snorkel in the airbox, but don't tighten the airbox back up yet. A flat-head screwdriver may be useful for getting the snorkel back into position.

E. Mounting the new VR

  1. Locate the bolt that holds on the helmet holder cable - remove that bolt, discard the cable. There is a washer on this bolt - leave it in place against the overflow tank (my bike was dirty enough that it just kind of stuck there). Discard the original bolt as well.
  2. Take the new bolt, thread it through the VR (fins on the VR go OUT from the motorcycle), add three washers, add the spacer, add the remaining washer (the one that remained from the helmet cable).
  3. Feed the wires from the VR through the frame of the bike into the seat pan.
  4. Thread the bolt into the hole with some blue Loc-Tite (you might consider replacing the threaded clip here with a real nut - while I haven't had any issues after 3 months of street riding, rough roads or off-road use may require more tightening than the original clip can handle).
  5. Adjust the VR to ensure clearance between the VR and the overflow tank and between the VR and the snorkel (if you're not eliminating the snorkel) before you tighten down the bolt.
  6. Tighten the airbox bolts back up.

F. Connecting the wires

  1. The yellow wires from the VR (with connector from the old one) connects back where the old VR's yellow wires came from. Before making the connection, put a blob of dielectric grease in each of the female connectors to prevent corrosion.
  2. The red wires connect to the positive battery terminal (apply dielectric grease to the ring terminal from the VR, any other wires going to the positive terminal, the terminal itself and the terminal bolt).
  3. The green/brown wires connect to the negative battery terminal (same procedure with the dielectric grease).

Start the bike up - hopefully everything works. Put the plastic and seat back on.

Alternative Relocation

Misc Questions

How can I prevent it failing (for as long as possible)?

  1. Get a sealed Battery (See the Flaying the VR FAQ for WHY)
  2. ALWAYS make sure your battery level does not drop too far.
  3. Move the VR to a Cooler Place.
  4. Consider adding in a Relay and a Diode as per the Flaying the VR FAQ.
  5. Make sure the Ground Wire is Properly Connected
  6. Don't Wash it with Cold Water when it's HOT.
  7. Keep it clean and uncovered. i.e. Don't put any cloths or anything over it or close to it that will prevent airflow (in the Stock Location).

Surely if it's Overcharging the Battery, this can't be good for the Battery in the Long-term?

Does Submerging it unduly affect it?

If it fails, can I completely disconnect it so I can get home?

What else could it be if it is NOT the Voltage Rectifier?

What's the Chances of it happening to me?

VR Autopsy

An Autopsy of a Classic (Funduro) F650 Voltage Rectifier / Regulator - Failed Classic VR

Yesterday I took Chris from Santa Cruz' dead VR to the Failure Analysis lab and we x-rayed it. I have some pictures that I will include in the final report. The cause of failure was a lead that came loose from what was either a capacitor or diode. It looks like the component spilled its guts, too. We couldn't see much more, shooting through the aluminum heat sink.

Chris in Santa Cruz sent me his dead VR for an autopsy / reverse engineering. This is a composite of two x-ray pictures of the unit, as received, shot through the heat sink. The three vertical bars are connected to the phases (yellow wires) of the alternator. These have diodes stamped into them that engage the two horizontal buss bars in the middle. One bar is ground (brown wire) and the other is positive "12V" out (white/red wire). The green "sense" wire is the small one running up the right side to the regulator portion.

See those blobs near the top of the picture? We thought those might be capacitors or diodes. Take a CLOSE look at the one in the middle phase. That doesn't look right. So we zoomed in on it and saw what is probably the cause of failure for this unit, an open circuit.

X-rays have to have a lot of energy to go through metal. The VR is potted in some sort of epoxy. We figured we'd have a better view if we got rid of the metal and the epoxy. An infrared spectrograph indicated that this epoxy was a highly cross-linked compound that probably would not respond to solvents. Sometimes you can heat up an epoxy and it sort of melts, allowing you to remove the potted components. Not this epoxy. This would likely heat up until it started to "decompose" which is a fancy way of saying "catch fire." So I sawed off the heat sink.

This allowed us to shoot lower energy x-rays through the epoxy in the hope of seeing more. We did. If you look very closely in this picture, you can see evidence of circuit board traces toward the right end. And there are clearly a few components there.

Lowering the beam energy even more means that you can't see through the buss bars as well. But you CAN see the traces in the circuit board more clearly.

Since the key to this thing is that regulator board, we decided to remove it. This was done with a vise and hammer and screwdriver. The potting epoxy was laid down in two stages and didn't adhere to itself homogeneously. So we could split it.

And then out came the regulator, dipped in white nylon. Here is the regulator. There are two transistors, three-terminal devices in the lower left quadrant. There are three resistors, on the left side, probably of two values. In the middle section are two other components. The one at the top appears to be a diode and the one below it is probably a resistor. We guess that the diode is a zener diode for a voltage reference.

We played with the beam energy a little bit to see if we could get any other clues

We thought we saw a number and found that we did

These three terminal devices are either transistors or silicon controlled rectifiers.

We did mass spectrometry on the white stuff (in red below) and found it to be a pretty good match to a known sample of a polydimethysiloxane compound (in blue), commonly called silicone.

Paul didn't have any of the hexo-flouro-bad-shit-solvent on hand in the lab that will dissolve most silicones. So we tried heating it in an oven to 150 degrees C for awhile. Some of the lighter aromatic stuff left, making it a bit more brittle. But it didn't melt or liquefy at all. If we heated it up much higher, the solder would start to re-flow. Silicone is real easy to carve with a sharp knife. So, Exacto-time it was.

Failed Electrex VR

Finally talked to Ritzo at Electrex.