Omega 450 FAQ

Straight FAQs About the Omega 450 Alternator

Q : What are the advantages of the Omega alternator over a stock system ?

A : Performance, reliability, and cost. The Omega alternator is able to provide superior battery charging ability at lower engine speeds, with the battery getting 14 volts from 2000 RPM and up. It is also capable of easily supporting up to 32 amps worth of accessories such as extra lighting and heated gear, while still being able to maintain a full charge in the battery.

The Omega system introduced in 2002 was the first widely available, factory - made improved charging system offered for the BMW air-cooled Boxer - only after 32 years of of really needing one! Over 750 units sold are now in the field, the one with the highest miles on it now has almost 200,000 accumulated. There are several out there on motorcycles being ridden around the world, right now. Others have already come back from those trips.

The component parts of the kit are all improvements of the corresponding original parts, designed and built to withstand the requirements of operating with THIS system, with long - term durability being of primary concern.
There is even some compatibility with original charging system parts.

The Omega system includes a fail - safe 330 ohm resistor circuit for the generator warning light, which, on a stock system, will prevent alternator function if the bulb blows. The addition of the by-pass resistor circuit allows continued charging even if the warning light bulb blows, which actually is a pretty rare occurrence. This is a peace of mind addition that can prevent a $1. 50 bulb from causing at the least a huge inconvenience, and at the worst a very expensive rescue when the battery expires in a difficult place.

Have you priced the BMW genuine parts for alternator repairs on a stock system ? Prepare to be shocked : these are the new parts equivalents of the ones replaced in an Omega kit. *

Alternator rotor $488. 40
Stator 208. 54
Brushes 7. 15
Diode board 125. 55
Charge return wire 24. 50 ( YIKES!! For a simple piece of red wire, 5" long, with 2 connectors! WHY? )
Stator wire set 16. 66
Y wire 2. 94
Diode mounts 24. 44
H/O voltage regulator 132. 34
Diode ground wires 5. 68

TOTAL AMOUNT, $1036. 02
*Source : Max BMW On - Line parts store, 10 Jan. 09

Considering the modest 17 amp performance available from the stock replacement parts from BMW, their astronomical prices have become ludicrous. Why pay more for such reduced expectations ?

Q : What makes the Omega able to produce so much more current than a stock system ?
A :
The most critical factor in AC current production is how fast the magnet poles of the rotor can be moved past the coils of wire in the stator. Since the electromagnet rotor is attached directly to the BMW crankshaft, the alternator can only spin as fast as the engine, unlike a remotely-mounted alternator turned by a belt and pulleys which makes it very easy to spin the alternator much faster than the engine by varying the size of the pulleys. The direct - drive alternator design is great for compactness and mechanical simplicity, but is totally dependent on having enough engine RPM for adequate charging.
The Omega alternator higher output is achieved by making the rotor diameter much larger ( 81mm versus 74mm, stock). The larger diameter means the circumference of the rotor is spinning faster, thus switching the magnet poles at a higher rate for a given RPM. Larger wire in the stator windings and a much more efficient diode board completes the overall improvement in current generation.

Q : Will the stock wiring handle the increased output ?
A :
Yes, no problem - the current is still regulated, and all heavy load - carrying alternator wires are replaced with new, larger gauge wires.

Q : What are the advantages of the Omega over other types of charging systems ?
A :
The Omega is based on the Bosch - type excited field alternator, a very well known, time - proven design used in millions of cars, trucks, boats and aircraft for the last 50 years. This system only charges as much as the battery needs to keep it at roughly the same voltage at all times, working only as hard as it needs to.

The rotor winding is supplied with varying amounts of current from the regulator to change the strength of the electromagnet ; the stronger the magnet and the faster it spins, the greater the charge produced. Modern, solid - state regulators can control this activity very closely. Very seldom is the system called upon for sustained maximum charge, so the parts are generally unstressed in keeping the battery charged. As extra loads from more consumers may be applied to the battery and begin to lower its voltage, the regulator just raises the charge rate as needed.
The separation of the diode and regulator components makes for an easily diagnosed and serviced design, familiar to mechanics. The voltage regulator or diode bridge may be individually replaced, as needed.

Other alternator designs have used permanent magnets spinning past coils to generate AC current. These are very simple systems, typically used in low RPM applications that have minimal electrical requirements. Since the magnetic force doesn't change, output is basically always at maximum above a certain RPM. Then, the problem becomes what to do with the excess current, beyond what's needed to keep the battery charged. In old, crude designs the excess current was fed through a diode and directly to ground via a large, finned aluminum mount that looked like a miniature cylinder head. The excess current was wasted as heat, in the airstream.

In more modern designs, the voltage may be controlled with solid-state devices that are supposed to cut the peaks off the voltage waves, above a certain value, and so limit the amount of current that then has to be rectified with another set of diodes before it can charge the battery. If these functions are poorly controlled, stator overheating damage can result from sustained high RPM operation, especially with a marginal battery. Usually, these regulator / rectifier functions are all wrapped up in one box that controls both. If either side fails, it cannot be easily repaired and the whole unit gets replaced.
Heat, whether produced internally by electrical activity or externally by location, is still the enemy of all electronics. This applies to magnets, as well - only the best engineered magnets using rare-earth materials are able to maintain their full strength for years and years when subjected to heat.

Q : Doesn't the Bosch design alternator still need brushes ?
A : Yes.
So what ? Brushes are cheap at under $10 a set, and last for 75,000 miles or more. A new set of no-solder, easy - install brushes are supplied with the Omega kit.

Q : What parts make up the Omega alternator kit ?
A :
Rotor, stator, brushes, diode board with new wiring, diode board solid mounts, solid - state voltage regulator, generator light bypass circuit, rotor puller tool, and a 6mm allen wrench.

Q : Can I use any of my stock parts ?
A :
The original voltage regulator and diode board will fit and work with the rest of the Omega system. The original regulator will not allow the battery to charge as fully as the one that comes with the kit, 13. 8 V versus 14. 2 V. The original diode board might deteriorate if asked to endure the full capacity of a heavily - loaded Omega system for a long time, but for a diagnostic tool or a get-home fix it would be fine.
The original stator housing ( the round, aluminum casing that has the brush holder mounted on it ) is re - used.

Q : What makes the Omega parts so much better ?
A :
The diode board is constructed on a high - temperature printed circuit board, with 8 solid-state Mitsubishi diodes set in a massive finned aluminum heat sink. All 4 mounting points are ground paths, so the sore spot of the original design is avoided entirely. All new, heavier gauge wires are attached to the diode board and a new B+ wire for the charge current return path is included.

The rotor is made from forged steel, for extreme rigidity and better magnetic properties. Each rotor is precision balanced to a speed much higher than a BMW engine would ever be able to attain.
The stator frame steel laminations are precision laser - cut, not stamped, so that they are flatter and more can be stacked into the same available height.

The voltage regulator is a solid - state design that has the upper control voltage set at 14. 2 volts, which is the ideal voltage for optimum function of ALL electrical equipment on the bike. Modern sealed batteries will especially be happy with this higher setting.

Q : What about rotor and stator interchangeability ?
A :
Nope, they're special because of their larger diameter than stock pieces. They have to be used as a set, no intermixing with original parts is possible.

Q : So what do I do for a replacement if I'm in a ditch in Timbuktu and need a rotor ?
A :
Buy and carry a spare, if you're into total self - sufficiency, for less than half the cost of a new, stock rotor. Or, call Motorrad Elektrik World HQ on your satellite phone and we can express ship a spare to any recognizable, permanent address.

Q : What modifications to my bike are required to install the Omega system ?
Zip, nada, nil - The installation makes no changes whatsoever to the original wiring harness or engine cases. Except for the soldering of the new stator wires to the existing stator housing terminal block, it's a bolt - up process. No grinding, cutting, rerouting, or re-wiring. Take the old parts off, bolt the new parts on and plug them in with totally compatible connections.

And, as easy as that is, we can make it even easier if you don't want to do the soldering bit yourself : you can just send in your stator housing to Motorrad Elektrik, and we'll be glad to do the entire stator / brush install for free and send it all back together, so it comes out of the box and goes right onto the bike.

Q : Can I install the kit myself, or will I have to pay a shop ?
A :
I dunno - how good of a mechanic are you ? Can you read and comprehend written instructions ? It's really quite simple, but then again some people should have to get a license to posess tools. View the complete installation instructions and see what you think.

Actually, it's well within the capabilities of most Airhead owners, if you have any familiarity at all with what's lurking under the front engine cover. There's been at least a couple of successful stone novice installations done by people who did not know their bike came with a tool kit. No special tools are required beyond the one that comes with the kit, basic hand tools are all that's needed. We're always happy to answer questions, it's never a problem to provide more information if anything is unclear.

If you do pay a service provider to install the kit, anyone who calls themselves a BMW Airhead mechanic and takes money for it should be able to do the installation in an easy 3 hours or so. Less, if it's a model that does not use the goofy rubber mounts under the diode board - they can be quite time - consuming to change.

Q : Do I need to change the coils or do anything to the ignition system ?
A :
No changes are required to the ignition system at all. The Omega alternator is compatible with all years of original ignition systems as well as Dyna and Boyer aftermarket ignitions.

NOTE: The web site for the Omega ignition system, made by a German company that has no connection whatsoever with Motorrad Elektrik, claims that the Omega diode board is incompatible with their ignition system. While there are several of our customers known to be using the combination of Omega diode board and Omega ignition with no problems reported, you may experience different results.

Q : What models can be fitted with the Omega alternator ?
A :
There are essentially only 2 versions of the kit, to fit all models from 1970 through 1995. 1970 through 1976 models have a 105mm diameter stator / crankcase interface, and all 1977 through 1995 models have a 107mm diameter.
The original stator and housing used on the /5 models from 1970 through 1973 is considerably smaller than the Omega stator, and this makes the original stator housing unusable for Omega installation. To mount the Omega on a /5, a 1974 through 1995 stator housing, BMW part #12311243002, must be used. The original /5 brush holder assembly is exactly the same and fits the later housing. This was exactly the same part on all sizes of engines made from 1974 through 1995. The housings can usually be purchased used, fairly inexpensively.