R100GS Omega 400W Alternator Installation
Almost since BMW started building air cooled twins, riders have wanted more electrical power than the anemic factory alternators provided. The problem is even worse today with the availability of heated grips, electric jackets and vests, and high output lighting. Enterprising hacks have arisen that drive automotive alternators with belts and pullies, but the unsightly mess at the front of the motor is more than most of us can stand. Attempts to change out voltage regulators to versions that charge at higher ratings help some, but at the cost of dried out and fried batteries if the bike is used mostly at freeway speeds. BMW has made higher output alternators available in police bikes, but even their 220 watts is pretty impotent. Finally, Rick Jones at Motorrad Elektrik, after years of experimentation and development, has brought to market the Omega, a 400 watt powerhouse that promises to banish electrical charging problems forever. The kit, which sells for about $600, includes a new rotor, stator, diode board, solid diode board mounts, voltage regulator, alternator brushes, and wiring harness, along with a rotor removal tool and all the allen wrenches you'll need to do the swap. You keep your old parts, as both rotor and stator are built on new cores. If you've already upgraded your diode board to a Thunderchild, that will be replaced as well. The eleven diodes on the new board handle the Omega's higher output without the overheating exhibited by the Thunderchild. Rick says you can still use a Thunderchild in an emergency, so it might be good insurance to carry it along if you plan to travel to the ends of the earth.
So how does the Omega system boost power to such unprecedented levels while managing to hide under the BMW engine cover? The secret is in increasing the number of windings in the rotor and stator. This makes the magnetic field generated by the rotor stronger, and provides more wires for the field to cut in the stator. Comparing the Omega (right, above) with the BMW rotor shows little difference,other than increased pole area which might also improve magnetic field strength.
The Omega stator (left, above) has more wires of a heavier gauge to handle the higher currents, but retains the BMW part's overall dimensions. No modifications are needed to install either part, with the exception of moving the alternator cover from the old stator to the Omega.
Enough theory, let's get started with the installation.
Begin by disconnecting the bike's ground cable from the back of the transmission housing, just above the right side foot peg. The lug on the ground cable comes from the factory with a hole, so you'll have to remove the attachment bolt that also serves to secure the speedo cable. Now would be a good time to snip out the end of the eye so in the future all you'll need to do is loosen the bolt to remove the cable. Push the cable aside and make sure it isn't touching anything metallic thus remaking the ground connection. Wrap it in a rag and hook it on the drive shaft boot to keep it from moving around.
Remove the seat and fuel tank so you'll have good access to the top of the motor. Now move to the front of the motor and remove the two socket head screws that secure the cover. The cover should now pop off (there's a steel dowel at the bottom, so you won't be able to wiggle that end). Set the cover aside
With the cover off you'll be able to see the ignition sensor (it's the can at the bottom), the alternator (the next big circular thing above the sensor) and the diode board (perched up under the frame rails at the very top). You'll be replacing almost all the wiring you see with new bits from the kit, so start by pulling connectors off the alternator and diode board.