Enduralast rotor upgrade for BMW airheads: First Impressions


The following includes my first impressions after installing an Enduralast 450 Watt system from

Euro Motoelectrics

The bottom line is that from about 1200-1300 rpm onwards, the system puts out 14.1 to 14.2 volts. At idle, it’s between 12.4 and 12.6 volts. I installed a Datel volt meter to give me a constant read-out during riding. I puttered through town this evening and briefly hopped on the freeway. At all points the voltage was constant between 14 and 14.2. Yesterday, after ensuring I had rigged everything up correctly, I wired up an electric vest and a 70 Watt power inverter to the battery. Flicking the high beam on and off at idle makes the voltage blip, but it returns a steady number after a second or so. Since the inverter and jacket didn’t seem to make a difference in the voltage readout yesterday, I did not wire them up for the test ride.
The kit contains a rotor (solid magnet) and stator, a mounting bracket, a rectifier and a set of wires, connectors and eyelets etc. I used only a fraction of this as the kit caters to an array of mounting options. There’s even a rotor puller bolt included.
The installation is relatively straightforward, but you do need to read the manual carefully. The wiring diagram is a no-brainer. Since I am going to move this system to my G/S in a few months, I did not bother removing any of the original wiring. Since none of it is needed in the meantime, I taped up all the ends and left them where they were.  



First job is to remove the original stator, rotor, diode board and voltage regulator. I left the voltage regulator in place, courtesy of two spun screws.

Mounting the rotor is the same procedure as a regular one. Since we’re dealing with a solid magnet rotor, you want to make sure your wallet and credit cards are not in the vicinity. I wondered about the Hall sensor with this thing nearby, but a timing light check confirmed nothing had changed.
The stator is mounted between two aluminums brackets and screwed into place with 3 screws in the same location as the original. No brushes here … this is a “contact-less” system. As with the original stator, you need to slowly easy it into place and tighten the screws in turn. There is one big wire going up and out of the front cover cavity, that’s it. The only other wire under the front cover after the install is the wire to the timing can (for post-81 machines). Lots of space to mount a small box with tools where the diode board was… hmm.
I ended up mounting the rectifier to a frame tube and ran a car-size ground wire to the battery negative. This was pure laziness on my part, as others have installed this rectifier under the tank after removing the voltage regulator. It fits in that space.
The wiring is simple: The voltage regulator plug ground and blue wire are used (with spade connectors), a wire (with provided 30 amp fuse) to battery positive. Two plugs connect the rectifier to the stator, one wire connects to a switched positive. For the latter you need to connect to a wire that gets “hot” when the ignition is on. One of the spades on my coils was hot so I used that.
I spent most of my time trying to figure out where I wanted to mount the rectifier. The RT has less space than other configurations and I could not remove the voltage regulator. In hindsight, I preferred it that way.
During riding I noticed not much difference, except that my stock voltage regulator was reading much higher than before. It’s nice to know that even when you’re loitering through town you’re not draining the battery. I was somewhat concerned that given the strength of the magnet, there would be more drag on the motor and hence I’d have to adjust idle (more fuel consumption…) but that proved to be unfounded. As well, the rotor weighs less than the stock one. I touched the rectifier at the end of the ride to see if it had heated up, but it was cold.
I’m going to eye-ball this setup for a while and decide whether I want to move this over to the G/S. This whole thing started when I contacted John Rayski (Euromoto Electrics) and quizzed him on whether he wanted to have a “guinea pig” for his new system. He was happy to provide me a system, gratis. Next April, I’m off for a LONG trip across Europe to China and beyond. In order to eliminate the need for carrying an extra rotor and diode board, as well have better charging, I want to take this setup. Since it’s on the RT, I’ll put ample mileage on it between now and then to provide me with enough comfort to put it on the G/S.

Another (small) benefit of this system is that the charging light, although powered as with a stock setup, is not required to function for charging to take place.

Pictures of the rectifier mounting



























Comparison of 3 rotors

The middle one is the Enduralast one. The left one is stock and the right one is a Motorrad Electric rotor. The Enduralast is the lightest.


Pictures of another install (used with permission)

Rectifier install on the same GS

Pictures at various speeds on my RT

Note: The digital voltage readout at the left in the pictures below is about 0.2 volts below what I measured at the battery with the same voltage meter. Probably due to some loss as I spliced the volt meter into a switched circuit up front. The high beam is on during the test.

800 rpm

1000 rpm

1100 rpm

1500 rpm

Feb 1, 2006
After a few thousand miles, the next step is to move the Enduralast over to the G/S. I contacted John and got a spare rectifier to take along on the trip. Mounting the rectifier proved unexpectedly easy. I was dreading having to fight for space under the Acerbis tank where I'd only last week managed to squeeze in an alarm system. A visit to my welder netted the simplest of solutions. After debating a bracket welded to something given the tank's hogging of all the frame space, he suggested an aluminums plate right behind the battery. That would allow the battery straps to catch the plate and provide a mounting surface for the rectifier. Since it's about as close as you can get to the battery, this seemed an excellent plan. Below is a pic of the aluminium plate. It's 5.5 X 7 inches. It sits right along the battery (which is the same size) and fits snugly between the battery box and the battery. The rectifier points backwards towards the rear fender. It's completely in the open and does not interfere with anything. I run a full toolbox under the seat, FWIW. The wiring runs downwards. Come to think of this, I should have followed the same system on my RT. I run a smaller diameter Odyssey PC 680 and there is a LOT of room at the front of the battery to do something similar.

Feb 23, 2006
Trip preparations have kept me from playing any further with the setup above until yesterday. I received a spare rectifier from John at Euro Motoelectrics 3 weeks ago. I wired the system up on the G/S and ensured I had matching connections on the spare for an easy swap-in if needed. The pics below link to the unadulterated full-size ones. They are around 2MB each.

As you can see above, the install is complete. You are looking at the left of the bike (R80G/S). A few things still need to be taken care of, such as shrink tubing over a few connectors and protective cable sheathing, both of which I ran out of towards the end of the day. I opted to cut off all the connectors to the rectifiers and replace them with SAE 10 gauge two-prong plugs, as seen in the lower left of the picture, although this one is auxiliary power for an air compressor/electric vest. Maybe overkill, but this allowed me to configure the spare rectifier the same way, so that in case I needed it, it would be much simpler to replace.

The backing plate was measured to fit the battery and sits inside the battery tray at the bottom. At the back, I have 2 counter-sunk screws to avoid contact with the battery case and for security I added 2 strips of bicycle inner tube as vibration buffer. Again overkill as the battery case is rubber mounted. The battery straps hold the battery in place just fine and there's a tad more tension due to the plate, but not much. The fender is the closest thing to the rectifier, but there's about 3 mm of room in between. A perfect spot for the rectifier.

Here's a second view from the left side:

Here's a view from the top. The red wire is an extra ground.

So far, so good. I'll update this page if needed in the future.

Jan 15, 2007

I just returned from a 20,000 mile trip through Europe, Middle East and Asia. The system worked flawlessly. More info at http://www.nohorizons.net

Feb 1, 2008

I installed an Enduralast on my RT as well now.

2012 Update

After the initial success of the Enduralast on the G/S for the 2006 trip, I purchased a system for the RT as well. My RT is an 1983 R80RT. With the system on the RT I started to have a few problems in 2009 and in 2010 it required more invasive action. To follow the ups and downs of the Enduralast process, a few points of note:
- Both the G/S and RT have near identical setups in terms of electrical wiring and both have a PC680 Odyssey battery.
- The wiring harnesses I made for the G/S and RT are such that I can “plug and play” rectifier units between bikes if needed. I initially did this for both rectifier units associated with the G/S in case I needed to swap the spare in.
- Both bikes have Datel voltmeters installed. These are identical and very accurate.
- When I received the initial system from John Rayski in 2005, I also received an extra rectifier unit. In the following, I will refer to system 1 and rectifier A and B. System 1 and rectifier A & B are associated with the G/S. System 2 and rectifier C is associated with the RT.
- System 1 was installed into the G/S on Feb 23, 2006 after testing it on the RT for a while. Rectifier A was installed, rectifier B packed as spare.
- System 2 was installed in the RT on Feb 1st, 2008. Rectifier C was installed (no spare purchased).

A few years after installing system 2, I noticed intermittently voltage spikes, to 18.3 volts for short periods of time. These were not gradual, more like someone flipped a switch on and off. The spikes lasted for about 30-40 seconds before the voltage flipped back down to 14.2 volts, as normal. This became an increasing occurrence and at one point, the voltage “stuck” at 18.3 volts. At that point, I pulled rectifier B (from system 1) out of the spares box and plugged it into the RT (system 2). Strangely enough the voltage issue was still there! 18.3 volts all the time. The immediate analysis was that the problem was not with the rectifiers but somehow associated with the wiring, stator coil, battery or other part of system 2. As a double blind test, I put rectifier A (from the G/S) in the RT and things were normal (14.2 volts). I also put rectifiers B and C in the G/S and both showed 18.3 volts. The puzzling thing here was that rectifier B had never been used earlier as it was just a spare for the initial trip and although wired the same as rectifier A, I had never tested it until I plugged it into the RT.

I sent both rectifiers (B and C) back to John Rayski and although incredulous at my findings, he sent me a new rectifier (rectifier D) for system 2 for free. This was wired up with the same harness as the others, installed and works flawlessly to this day.

In June of 2011, I purchased a new spare for the G/S (rectifier E) and installed it in the G/S, keeping rectifier A as a known-good spare for the 2012 trip. So far, so good.

In messing around with all these issues, I did discover some other quirks of the system. Initially, in 2003, the rectifiers were shipped without decent connectors to the wiring, with John pressing the issue that you had to clip off the attached connectors and attach proper connectors (supplied by John) instead of what came out of the factory. With rectifiers D & E, I noticed proper connectors (SAE trailer plugs) had been used from the factory and given the change, decided to use them. This was a mistake as the black wire into the rectifier seems to very sensitive to voltage changes and I had some issues on system 2 with Rectifier D. I even completely rewired the system front to back with all new wires and connectors, but it wasn’t until I clipped off the SAE plug attached to the white (voltage regulator control light) and black (switched power to activate the rectifier unit), that things went back to happy.

All in all, despite the issues I’ve had so far, I am happy with the setups and can’t foresee any changes here. Hopefully the rectifiers (Italian electronics) don’t act up again.

More information about the Enduralast at the Euro Motoelectrics website: http://www.euromotoelectrics.com/enduralast.html