F650 VR Relocation FAQ

edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 05 January 2007, by Winter #1935

• The Voltage Rectifier/Regulator Relocation Project - The Original
• The Voltage Rectifier/Regulator Relocation Project - Alternative #1
• Feedback

For other related FAQs:

• Refer the Voltage Rectifier FAQ for more information on what the VR does.
• Flaying the VR FAQ - for some modifications to stop the VR toasting your battery and the VR wires themselves (see note below, the best solution is to install a GS VR).

The Voltage Rectifier (VR) on the Classic is not located in the most ideal location. The lack of airflow is probably one fact in why so many of the Classic VRs fail. This FAQ contains information on how to relocate your VR to a better spot. (This problem does not affect the GS models, as the VR is located on the RHS up near the bash plate).

by Flash #412

Motivation

The voltage regulator / rectifier (VR) comes from the factory bolted to the top of the rear fender, under the seat, no where near any air flow. This thing has fins for a reason, because it gets hot. Having it stuffed up under the seat does not cool it very effectively. The stock configuration includes a snorkel sticking out of a big hole in the airbox under the right side cover. Removing this rubber snorkel is simple.(See Note 1 Below). You just squeeze it and pull it out of the hole. However, you will then need to take the tops off your carbs and drop the needles (physically) one notch (See Note 2 Below). You can do this with the carbs in place. It is easy but not covered here. If you do that, you get a little more intake noise and maybe a little bit more power. You also get a big place where the snorkel used to be to which you can relocate your VR. This will put it in a position where the fins will get some air flow even at idle, due if nothing else than to the air intake being right next to it. Furthermore, the chimney effect (See note 4 Below) of the fins will be able to work as they will be oriented vertically. The picture below shows the VR in it's original position as well as the Big Hole in the airbox where the snorkel used to reside. The white (burp) tank is for the radiator overflow. We're going to use two of the three bolts mounting that to mount a bracket for the VR.

Method

The bracket I got was made of galvanized sheet metal. I don't have a drawing for it because someone else made it and sent it to me. If I do get a dimensioned drawing, I'll add it here. The burp tank is mounted with three tinnerman nuts. I removed two of them and threw them in my spares kit. I removed the bolts and put them in the trash. I used some REAL bolts and some Nyloc nuts instead. The picture below shows the bracket from a couple of angles. You must be careful that you don't end up with the VR in contact with the burp tank. If you do... the burp tank will quickly get a hole in it, I'm sure.

On thing that happens is that the ground wire (See note 3 Below) will no longer reach the stock mount from the new location. Since I am not using tinnerman nuts, I just scratched the paint away where the ground fitting was going to go in order to make SURE that it is in good contact with the frame. I checked it with a meter between the fitting and the motor, after tightening the bolt. It has GOOD contact. Refer the Misc Electrical Q's FAQ for Ground testing.

After getting the bracket mounted, you can use the nuts and bolts from your original VR mounting to relocate it. (I changed mine to real bolts a while back.) Below are a few shots of the VR in the new position. You can see that the wires snake nicely between the airbox and the frame and reach their mating connectors quite nicely. Notice how the fins are in a vertical orientation for improved cooling in still air. The shot from the top shows how the VR is inside the contour of the side cover. You can also see how there is now additional under-seat storage area. Although I'll probably clean up where the VR used to be and slap some duct tape over the holes before storing more stuff there.

The photo below is not a very good shot. But it was the best I could do. There is plenty of clearance between the side cover and the VR. I am confident that the VR will be much happier and cooler in its new home.

Note 1: On Removing the Snorkel:

• You don't have to remove your snorkel to relocate your VR. I cut my snorkel down about an inch or so, then plopped the VR in front. Any improvement in airflow from the snorkel trim was offset by the VR placement. I didn't notice any difference at all after making the change, so as far as I can tell, I'm in good shape (plus, the snorkel sucks air through the VR fins for additional cooling.) Mark #403

• I did what Mark #403 did. Cut the Snorkel, about an inch off the end, in a curved line. Sucks Air nicely over the VR. Kristian #562.

• If you just trim the snorkle, you are not really altering the airflow characteristics of the airbox, and probably do not need to adjust the carb needles. If you fully remove the entire snorkle insert from the airbox, as Flash did, you are effectively enlarging the intake, and then should consider adjusting your needles as Flash suggests. HsN

Note 2: On Dropping the Needles :

• Quite a few people have puzzled over this comment, because conventional wisdom says raise the needles = richer, lower =leaner. However CV carbs (sometimes called Constant Velocity or sometimes called Constant Vacuum, that the F650 uses) use the pressure differential between the two sides of a diaphragm to raise the slide. The needle is attached to the slide. By removing the snorkel, you lower the effort required by the motor side to raise the slide. You have effectively raised the outside air pressure by removing the snorkel. In other words, for a given manifold vacuum, the slide now rises higher than it did before you removed the snorkel. This means that the needle is allowing more fuel in for the same throttle-plate opening than it was before. To counteract this effect, you need to drop the needle, physically, one notch. You do this by putting the clip in the next higher notch, physically.

Note 3: On Lengthening the (Brown) Ground Wire to Ground in the OEM Location:

• I also lengthened my ground wire to attach to the original frame ground, which I prefer, being more visible and resistant to corrosion, as you did, and in my case I expect no problems. HOWEVER: I used as short an extension as required, of 2 sizes heavier gauge, higher quality wire, and (very expertly) soldered on both the extension and the new, marine grade (higher quality) terminal, sealing the joint in heat shrink tubing. (It's a ground, so that's just for corrosion protection.) So I think I'm OK. If someone were to add an extension with a chunk of thin wire twisted together and sealed with tape..... there could be some interesting problems somewhere inconvenient. HsN

• Actually, I did the same thing. I used larger gauge wire, with good solder connections, and heat shrink tubing. The added length of wire amounted to about 3 inches. Bob#550
  Remount a Success!

• Good call, Bob. We wouldn't have known HOW you extended it had you not said so. Extending the ground wire could be a dangerous idea for the twisted wire and duct tape set. Flash #412

Note 4: Fin Orientation

The Question:

Since we received two more feet of snow, I have decided to relocate the VR before the riding season starts. I've looked at the FAQ, and decided to go with Mark's and Kristian's suggestion to cut down the snorkel, rather than remove it. Now, Flash suggests to mount the VR with the fins in a vertical position. Wouldn't it be more efficient to mount it with the fins horizontal? Any suggestions?

• With the fins mounted horizontally, you theoretically get more cooling by the airflow as the air moves over the fins toward the intake. I do not quibble with that. However, I chose to mount mine vertically for another reason entirely. When there is a lot of intake, i.e.: the bike is MOVING, there is also a lot of air moving around inside the cover as the bike slices through the air on its way down the road. Frankly, I don't see cooling being measurably different in that case whether horizontal or vertical. But, when we get to idle... there is when it might be different, and SURELY when the motor is stopped. Let's take the stopped case first. There is a phenomenon called the chimney effect that says that stationary cooling fins begin to establish a FLOW in still air when oriented vertically. Cooler air enters the bottom and rises as it is heated to exit the top, sucking more cool air in the bottom. When I turn my bike off, I will bet that my VR cools faster with the vertical orientation than someone who did the horizontal orientation. At idle... IS there enough intake to pull air through the fins? I don't know. If there is... then there SURE is enough air to turbulate the area around the vertical fins. Never mind the fact that BMW chose to mount it stuffed under the seat where there is NO air. Yeah, I thought about it and decided that at full chat, there is zero difference in the cooling by orientation. Stopped, vertical is better. And at idle... I believe it is a wash. I don't know about you. But my bike tends to be either RUNNING or parked. I don't sit at idle very long or very often. Flash #412

• Since I try to keep my bike moving, the idle theory doesn't apply to me so much. to be honest, it never occurred to me when I did the install. I don't think there's going to be much difference either way; moving it from under the seat and away from the exhaust is probably the most important thing. if I had to do it again, I'd still rather have the air flowing through the fins when I'm moving, since that's my bike's condition 99.99% of the time I'm on it. For kicks, if you do the math (and I hope I did it right) at 1300 rpms, you drawing about 30 cubic feet of air across the VR every minute of idling, which I would wager is more than the chimney effect. You can't go wrong either way, and I think we've probably given this topic more than it deserves, considering it's mostly speculation. Mark #403

• Sure, the idle CFM swamps the chimney effect. The question we don't have the answer to is... is the turbulence created by the 30 ft^3 sufficient to cool the fins to any measurable DIFFERENCE depending on their orientation. I think not. I agree. This horse is dead. The difference between H or V on the remount is mouse nuts compared to the fact that the VR is no longer smothered. Flash#412

The Voltage Rectifier/Regulator Relocation Project - Alternative #1
by Prof #001, with feedback from Erin & Chris Ratay
November 25, 02

The rectifier is an electrical device that regulates the voltage generated by the stator. On older F650 models the rectifier is located directly under the seat. It is the finned metal object, black in color, and secured with two 10mm bolts/nuts. There are three yellow wires bundled together, one brown wire, and a red/white and green wire bundled together coming out of the rectifier. The rectifier needs cooling for proper operation and this stock location does not provide adequate cooling.

The problem of relocating the rectifier is four-fold:

1. safety from road debris and moving parts,

2. airflow for cooling,

3. avoiding cutting/splicing wiring, and

4. where to drill mounting holes.

After a great deal of consideration and thought, it all came together. All problems were solved by relocating the rectifier on the underside of the flashing on the right side of the bike. Please refer to the pictures as marked.

• Note that on the bike in the photos, the canister has been removed. In place of the canister is the reservoir for the Ohlins shock, but the three vacuum tubes associated with the canister have been removed. Those tubes were attached to the flashing with a plastic “loop” at one point and threaded through the flashing in a “square hole.” This “square hole” and the other for the “loop” are exactly the same distance as the mounting holes in the rectifier – 65 cm or 2.5 inches. Problem #4 solved.

• To do this conversion, first remove the key from the ignition to prevent any accidental current flow. As with any home wrenching, read all instructions and if you feel the least reluctant, get a wrenching buddy or a mechanic to perform the operation. This one is simple. Remove the right side panel as you would for refilling/checking the coolant level.

• Don’t lose bolts or washers.

• With the key out and the seat removed, remove the ground wire (brown) from its mooring using a 8mm wrench. Replace that bolt. Other than the ground wire, there are two sets of wires coming out of the rectifier. With a bit of wiggling the two plastic connectors will unplug. Use a small socket for the bolts mounting the rectifier and a wrench for the matching nuts on the underside of the fender – both 10 mm – unscrew these and remove the rectifier. Don’t loose the nuts, bolts, or little washers.

• Reroute the wires from the bike side by the front of the cooling reservoir in such fashion as to allow maximum length; don’t stretch or yank electrical wires. Problem #3 is solved. With your left hand, temporarily hold the rectifier in the new position with mounting holes matching the “loop hole” and the “square hole” in the flashing – see lower illustration. Mark on the flashing the location of the wires that come out of the rectifier.

• Put the rectifier aside and cut a hole (I used a hand-powered bit from my carpentry tools) about 20 cm (.75 inches) so as to leave a small distance from the edge of the hole to the edge of the flashing. Now cut through from the edge to the hole – this allows the wires to be placed in to a small opening without having to cut/splice wires, thus avoiding more Problem #3.

• Mount the rectifier fins down pointing towards the chain using the original mounting nuts/bolts/washers. Problems #1 and #2 solved. It is necessary to use one larger diameter washer for the “square hole.” Look in your junk drawer for that. Use Loctite. Note in the illustration that the nuts are place on the up side of the flashing; it is easier to use a socket than an open-ended wrench on the underside.

• Relocate the ground on the mounting bolt for the cooling reservoir. The “helmet cable” is mounted in that same place. Problem #3 solved. I removed that “helmet cable.” Useless and it flopped around under the seat doing God-knows-what….!

• Check key/ignition and operation of lights and indicators. Replace side panel and seat and go for a ride!

Feedback

Feedback #1

I hereby nominate myself to be Wingnut of the Week. Last weekend I relocated my Voltage Regulator. I coulda swore I checked the ground's new location to make sure it had continuity with the negative pole of the battery.

When I parked, I put the fork lock on and inadvertently put the parking lights on. About three hours went by and when I went to start the bike, there was just enough power to get one rev outta the battery but I heard the exhaust valve decompressor click and the bike started right up. Whew, so glad I didn't have to bump start, my foot is lame and I had A LOT of pirate gear. I knew battery power was low because the dash lights were dim, but I made it the 12 miles home, with the headlight on (I didn't want to be stopped and the NYC Highway Patrol is on the hunt for revenue). I took the battery into my apt. to charge it up. It was down to 11 volts and none (that's right, zero) of the balls in my hydrometer were floating on all cells.

I looked in my notes and sure enough, this Wal-Mart battery had gone 12,000 miles in 20 months. The original battery crapped out at 13,000 miles in 17 months. I guess I was due for a replacement. Rode the Guzzi to Wal-Mart and bought an even cheaper battery than before (unfortunately, for the same price). I installed the new battery after a proper set-up and initial charge.
Just to make sure, I checked the voltage at the battery while the bike was running, 12.4 volts. This is not right. I grabbed my official Italian-bike ground check wire (standard tool on Guzzis), which is basically a piece of phone wire left by the phone company guys in the alleyway where I park. Put one end on the VR ground and the other on the battery and lo and behold, the battery voltage shot up to 14.25. Hmmmmm, I guess I really didn't check that the new VR ground position was properly grounded.

What I find hard to believe is that the old battery, which I'm certain I killed prematurely, Ged Rest It's Plates, ran for a whole week, 125 miles without being recharged. And those were all city miles, often with headlight on, brake light activated, turn signal on and fan on waiting at a traffic light.

So, for not properly checking the ground I killed my battery, unduly stressed my charging system, and spent thirty-five green USA dollars on a new battery. I think I deserve this week's Wingnut of the Week Award. Thank you. Shank.