Lamp theory & specifications, lamp substitutions,
relays, updating the /5 headlight (in various ways),
fuses, LED instrument lamps, large headlights,
special sockets, heavier gauge wiring,
HEADLIGHT MODULATORS, flasher.....and LOTS MORE!
There is a lot of difficult-to-find information in this article.
Copyright, 2014, R. Fleischer
Preface and a wee bit of lamp theory:
There are NINE (9) parts to this very long article.
I suggest that you, at least once, read the ENTIRE article!
This article covers Airheads lamps rather well. The information is also applicable to most motorcycles!!
I believe that LED headlamp conversions are NOT, at present, OK for installation inside or in place of stock incandescent headlights/housings, nor for H4 headlights/housings. Focus and light pattern problems. There are folks that don't care.
There are PROBLEMS in using HID headlamps, particularly with turn-on times, when going from low to high beam and when, in particular, the high beam is HID. There are one-bulb HID lamps, of course, but they still have lengthy turn-on to full power time. It may not bother you. There are also reflector and focusing problems that are, or can be, severe. The stock reflector and lens are not OK for most HID conversions of just the LAMP, but there ARE a few conversions for HID that are adjustable, and work SOMEWHAT better.
For a SEPARATE, ADD-ON LED or HID lamp, in its own housing, I have no objections.
Article 24B discusses the headlight relay, the internal diode, the handlebars switch, and how they all work together. It is NOT so simple, and that article's information is POSSIBLY needed, at least sometimes, to fully understand using larger wattage lamps, relays, ETC.
Vacuum vs. gas-filled bulbs (source: Don Kilpstein & Snowbum):
In the beginning years of making lamp bulbs, even as far back as carbon filaments in Edison's day, incandescent bulbs were made with a vacuum inside them. Air oxidizes the filament at high temperatures. Later, it was discovered that filling the bulb with an inert gas such as argon or an argon-nitrogen mixture slows down evaporation of the filament. Tungsten atoms evaporating from the filament can be bounced back to the filament by gas atoms. The filament can be operated at a higher temperature with a fill gas than with a vacuum. This results in more efficient radiation of visible light.
So why are some bulbs still made with a vacuum? The reason is that a fill gas conducts heat away from the filament. This conducted heat is energy that cannot be radiated by the filament and is lost, or wasted. This reduces the bulb's efficiency of producing radiation. If this is not offset by the advantage of operating the filament at a higher temperature, then the bulb is more efficient with a vacuum.
NERDY: One property of thermal conduction from the filament to the gas is the strange fact that the amount of heat conducted is roughly proportional to the filament's length, but does not vary much with the filament's diameter. The reason this occurs is beyond the scope of this article. However, this means that bulbs with thin filaments and lower currents are more efficient with a vacuum, and higher current bulbs with thicker filaments are more efficient with a fill gas. Sometimes, premium fill gases such as krypton or xenon are used. These gases have larger atoms that are better at bouncing evaporated tungsten atoms back to the filament. These gases also conduct heat less than argon. Of these two gases, xenon is better, but more expensive. Either of these gases will significantly improve the life of the bulb, or result in some improvement in efficiency, or both. Often, the cost of these gases makes it uneconomical to use them. At this point you probably better understand why the small diameter quartz glass H4 headlamps get so very hot, and why getting finger oils on the glass can limit the life of the bulbs.
Part 1. Headlight lamps, INCLUDING the /5 headlamps; relays and switches, ETC.
Special note: You may run into these two situations at some time:
(1) In the USA we drive on the RIGHT side of the road. In some areas of the world they drive on the LEFT side of the road. Light output from a headlight is shaped by three things; the reflector, the lamp internals, and the glass lens. These things are different, in most instances, between, say, USA and UK headlight assembly parts. Unless you have the correct parts, your road illumination will be POOR...or you will blind oncoming drivers.....or both. In various ways.
(2) The /5 did not come with a halogen H4 lamp; many have been converted. BMW no longer offers a kit for this, so most use the lamp assembly parts from a R65. The stock original /5 lamp was 40/45 watts, and very different in light pattern from the H4 halogen that came later. If you have a stock /5 glass, and install a common 9003 style H4 lamp, the diffusion is not pleasant for you as a rider. There are some special H4 lamps that will work with the stock reflector and glass, and they are listed in this section.
BMW stock lamps are arguably quite decent for your bike; except for the UNconverted (that is, STOCK) early /5 headlight lamp & lens/reflector assembly. The /5 (and many non-USA cars of the era) used a 40/45 watt (usually) non-halogen lamp, and these vehicles ARE vastly improved by upgrading the lamp, lens, and reflector to H4 halogen lamp items; by using the original BMW conversion kit parts (NO longer available); or, parts from an R65;....or using a special 64198 lamp, which is a 55/60 Halogen, made by Osram, and that lamp's particular construction and filament will work with the stock /5 reflector and lens. P45T is the /5 base size, and is a TAB type. For a chart of all sorts of equivalent numbers, such as 48884, and generic description, sketches, ETC., see:
NOTE AGAIN, part number 64198. There ARE other lamps of the H4 type with P45T bases.
The /5 and other 'foreign' vehicles of the era, that used the P45T base, are numerous. The P45T original lamp is not all that easy to find; and you may not want to use it anyway. The P45T base has NO TAB and the base is 45 mm in diameter. The H4 halogen lamp used on your later model BMW Airhead uses the P43T base, which is 43 mm in diameter. THAT base DOES have a locating tab. The locating tab is needed due to how the H4 lamp is constructed, in particular how the light beam is 'cut off', for high beam versus low beam. There IS a plastic adapter available, a ring with many notches, etc., that can be inserted into the /5 headlight, that allows common H4 lamps like the 9003, to fit. Those plastic rings are probably going to be very difficult to find, and probably expensive (perhaps $20-$35). If you can find them, they are OK to use...BUT!..... truly proper light beam characteristics are NOT had with the /5 reflector and outer glass, no matter what bulb or adaptor ring is installed. HOWEVER, that is a much less expensive method of obtaining a stronger light output. To find such an adaptor, search the Internet for something like this: P43T to P45T adaptor.
Note that the light pattern, using the original /5 housing parts, especially the front glass, will not be the same as later models, but you may find the light beam to be quite adequate, and certainly with an H4 lamp element, it will be much brighter. I suggest NOT using lamps more powerful than the 55/60 watts. It is true that the /5 had a high temperature rated socket (often used for high lamp wattage conversions on later models), but the wiring may not work well with 80 or 100 watt lamps...so, if you intend to so equip your /5, be sure to re-wire the headlight with larger gauge wires, and use relays to avoid overloading switch contacts.
HINT: Early headlight chrome rings were not screw/clamp fastened. Many have been lost along the road. It is best to fashion a method to secure them at the very bottom if you are using the early rings.
Be aware that while the 9003 headlight lamp is a generic number, the Euro lamp versions are generally of better quality, light pattern and output.
At this point, I thought it appropriate to give you some nerdy headlamp information. International specifications are not the same for the H4 headlamps as for USA specifications. You will find the information in this paragraph to be generally hard to come by. International H4 lamps are rated at 1650 lumens on the high beam and 1000 lumens on the low beam, both at +- 15%. Note that the specification has a maximum power drain, and it is 75 watts on high beam and 68 watts on low beam, and these specifications are for 13.2 volts. That 13.2 volts is more important than a quick glance tells you. For the USA, the equivalent lamp is called a 9003/HB2 or H4, and the lumens are 1580/910 +-10%. The draw is specified as maximum 72/65 watts but at 12.8 volts. You will find the drain about the same or somewhat higher at the European 13.2 volts. If you are 'lucky' your bike's system has a voltage of 13.8 to 14.4 AT THE LAMP (turned ON, of course). This raises the drain in watts, but increases light output, but can (and may not) decrease life. A regular incandescent lamp, such as nearly every lamp in your motorcycle, except the H4 or other Halogen lamp, has a life that goes down on a steep curve, as voltage rises over the rated voltage. BUT, in the other direction, a quite modest DEcrease in light is had with a QUITE MODEST DEcrease in VOLTAGE,.... YET!...that results in a HUGE increase in LIFE. BUT: The Halogen lamp is MUCH less affected in these ways. Halogen lamps should be run at 13.8 to 14.5 volts; they are very differently constructed and the halogen gas in them creates very different specifications for life expectancy. In fact, running a halogen lamp at quite too low a voltage will DEcrease their life. Halogen lamps continuously replate the lamp element as molecules of the filament boil-off. A simplified explanation. NOTE ALSO, that the voltage at the headlamp itself will be lower than the voltage as read at the battery. By how much depends on your bike's wiring size, condition of contacts and switches, etc. ...if you have added headlight relays....and, of course, at what voltage the alternator voltage regulator is set for. All things considered, the European headlamp bulbs perform better. If you have a headlight modulator, that USUALLY actually increases the lamp life, which is very different from any effect a modulator might have on a NON-halogen lamp.
You probably have an Airhead with the high beam flashing switch on the left end of the handlebar. That switch is part of the Hi/Lo selector.There is a peculiarity. The Hi/Lo switch section, in the stock bike wiring, handles the headlight's full current flow. That is why one or two relays are added if you install a headlight that is over maybe 70 watts, so that the switch does not wear out quickly. BUT, the push-to-flash section is a partially separate circuit. Thus, just how you wire up your relay (s) is important.
The best 'nearly stock' H4 lamp I have found, to be used with stock or with one or two relays, is the Osram lamp 64205, it is rated at 70/65 watts. It has a very nice output, at 1350/2000 lumens.
Very well made lamp, and just perfect on the beam and color; even though the catalogs call it an 'off-road' model (mainly because it has slightly higher wattage than standard). I think it will generally be OK to use this without adding a relay(s), but relays will improve light output and lengthen switch life. The H7 version is 64217 for those of you with auxiliary lamps that use H7, or, have other motorcycles.
Brighter yet is the higher powered 64206 at 80/85 watts and 1750/2400 lumens. ((The standard legal lamp is 64193 at 60/55 watts)). The rated life for these lamps is 100/200 hours when at 13.2 volts, under normal automotive type use. Expect somewhat less on a vibrating bike. If your lamp runs at 14.2 volts, the lamp life MAY be shortened, but I prefer that voltage for lamp performance. A headlight modulator (on the high beam) probably EXTENDS the life. Due to a peculiarity of how H4 Halogen lamps work (redeposition of material back on filament, etc) the temperature of the filament MUST be adequate for this to work well, and the LIFE of those lamps with voltage changes is NOT changed much as it is with smaller non-halogen lamps. Halogen headlamps will last a goodly number of hours on a motorcycle, if the voltage AT THE BASE of the lamp when the lamp is ON, is 13.8 to 14.3.
Here is a place that seems to stock these lamps; I have no experience with the company:
Blue-colored lamps, PIAA lamps, etc: The blue-coated lamps and other high priced trick lamps may SEEM brighter, but if you are in an oncoming car, you may think differently.....claims of 100 watt equivalent light output for 55 or 60 watts of power are dead flat wrong and TOTALLY misleading. If the lamp REALLY did that, it would burn-out VERY quickly. PIAA advertising is, in a lot of instances, bogus.
Part 2. LED's (Light Emitting Diodes)Bright 12 volt-rated LED lamps that fit the indicator sockets on some BMW motorcycle instrument pods are now available reasonably priced. Some give insufficient light output, particularly the beam is too narrow....there is not enough light to the sides.
PART 3. Interesting things about lamps, their life, etc.
If your motorcycle has just one stock rear running lamp, and it fails, then you have NO light to the rear at all, unless you have running lamps that have been added. Conversion of the turn indicators to have an additional running lamp function is not difficult, and an article is in this website:
When a common incandescent lamp fails it is almost always because the filament broke from being thinned or stretched/sagged, all from usage, over a long period of time. You can generally identify a lamp that is close to dying as the filament is visibly sagging. This is particularly noticeable in the turn signal and taillight and braking lamps. Thus, regularly, you should visually inspect the lamps. This is highly recommended for the rear running and brake light(s) and the front turn lights.
ONE LAST WAY to think about these things:If your voltage regulator is set for 14.9 volts at 70°F (this is when measured directly at the battery terminals, and is also the absolute upper limit voltage for most types of batteries), you might expect MUCH less life on your lamps. They will be "somewhat" brighter though. Probably 14.2 is a nice value for most batteries as a compromise, when one also thinks of battery life (most batteries have a longer life if the charging is set for 14 to 14.4, as opposed to lower voltage). The 13.8 that is often found will extend lamp life, and reduce how often you add water to the battery (assuming a flooded type battery). You can expect your BRAKE and TURN lamps to have REDUCED life as voltage to them increases. I recommend 14.2 to 14.4 volts for the readings AT the battery TERMINALS... for battery life, lamp performance and life....etc.
PART 4. Equivalents &/or substitutions (see PART 1 for headlamp numbers & information)SUBSTITUTIONS ARE JUST THAT, AND MAY OR MAY NOT BE TOTALLY EQUIVALENT. Various lamps in the airhead can be substituted USUALLY WITHOUT problems. One can purchase the original European lamp numbers at most autoparts stores; and, in general, the Euro lamps are better in several ways. However, there can be times you WANT a substitute or have to use one, for a variety of reasons. It may be an emergency burn-out; it may be you want a brighter lamp; it may be you want better performance, ETC. When I list a substitute, it means you will have a usable useful lamp. In many instances below I describe the differences, and what that means.
The rear running lamp, BMW 07-11-9-978-227, rated at a NOMINAL 12 volt and 5 watts, can be substituted by a very commonly available 97 lamp, which is rated at 13.5 volts at .69 ampere, which means that at THAT voltage, it would draw 9.3 watts, and, of course, it will draw less at 12 volts.
Regarding the substitution of 193, 194, 168, 161, 158 .....in the instruments. These lamps are called style T 3-1/4 and are used at the tachometer, speedometer, turn signal indicator, GEN. :
158 lamp = 2.80 watts, .20 ampere, rated 500 hours, a.c. (some rated at 13v and .24 ampere), about the same light output as 193 & 194.
161 lamp = 2.66 watts, .19 ampere, rated 4000 hours, a.c. Depending on where used, possibly Emergency use only.
168 lamp = 4.90 watts, .35 ampere, rated 1500 hours, a.c. This is a particularly good sub for the GEN lamp (/6 and later), as its characteristics ever so slightly enhance the starting of charging.
193 lamp = 4.62 watts, .33 ampere, rated 5000 hours, a.c. (rated at 14 volts too).
194 lamp = 3.78 watts, .27 ampere, rated 1500 hours, a.c.; a bit less light than 168.
2825 lamp = This is a 5 watt Euro spec lamp, but commonly found in the U.S. .....12 volt rated, not 14 as most of the above lamps. The 2825 lamp draws 0.4 ampere, and is brighter than 168 and 194, and a very nice, if slightly pricey, replacement for them. NOT super long life. This lamp develops too much heat, IN MY ESTIMATION, for anything but the GEN lamp usage.
2821 lamp = 12 volt rated, not 14. 0.25 ampere, light output fair, only a slight bit more than the 194, and not super long life, but longer than the bright 2825.
ANY of these bulbs will work adequately, the 168 & 2825 being a slightly better choice for the GEN lamp, wherein you want charging at the lowest rpm point where charging begins. Just a WEE tad of help though. You WILL gain more low rpm electrical output (at the cost of slightly lower maximum output) by using the latest 2.8 ohm rotor, & using the last stator type using the 14.2 volt electronic regulator. For the GEN lamp, one could also consider doing the resistor modification which will help charging slightly, and eliminate a charging problem if the lamp burns out (rare as that is). http://bmwmotorcycletech.info/genlampresistor.htm
Be cautious about the 2825 in other areas....due to the heat developed.
In general an E- prefix means European standards.
Instrument lamp: #07-11-9-978-279, 12 volt, 2 watt. This is usually the more difficult lamp to substitute.
12 volt, 21 watt BMW #07-11-9-978-370, substitute is common #1156. The 1156 lamp is rated 12 volts, 2.1 ampere, some books have it as 12.8 volts, 27 watts, 1200 hours (a.c.) (you will NOT get that number of hours)....which is a BIT brighter...you probably won't notice. The 1156 lamp is also available sometimes in both copper and plated bases and sometimes in aluminum. Get the silvery colored one if you can. The 1156 has two guide pins directly opposite each other and has a single contact base, and ONE filament. The Euro number for a close enough lamp is 7506. The 7506 is RATED at 13.5 volts, for a "12 volt system". That lamp is typically called a 21 watt lamp, and the Euro rating is 150 hours. You won't get that many hours, probably, but it is vastly more accurate specification for life, than the 1200 hours specified for similar lamps like the 1156, and even some 7506. These lamps are for one-function use, such as just a turn signal, or just a brake lamp. There is a 6 volt version, which is number 1129.
The 1157 lamp has the pins OFFSET in distance from the base; one pin is lower and one higher than the other. This was done so the lamp can only be installed in one position, not 180° around the other way.....and allows the lamp to be used in a dual contact, dual-function arrangement, in which one side of the lamp is much higher powered than the other. The high power section is the brake lamp, the low power section is the running lamp section. For practical purposes, the 1157 lamp is the same or similar to the 2157 and 7528. The 1156, and 1157 or 2157 lamps are close enough to the Euro lamp equivalents (7506 and 7528) to be used most any time as substitutes. They are not true equivalents. DO NOT confuse yourself about the 1156 single contact base. NOTE that the European lamps with SILVER COLORED BASES are generally to be preferred over the American brass bases. For those who have converted their turn signals to add a run function, the usual lamp used is the double contact lamp, common #1157 or 2157. The Euro number 7528 is better. For the conversion to turn/run, the lamp is wired for the TURN function to be the high power filament of the lamp, and the run function is the lower powered filament.
These lamps vary a bit in the filament rating and light output, but the truth of the matter is that it makes little difference, and how the specifications were done makes this a bit complicated to understand; but this article has, earlier, explained it adequately. Both the Euro and American lamps are the same size, have the same basic structure, but the way they are rated electrically and for light output is a bit different, which makes things confusing. Just go ahead and use whatever one you want. I am well-aware that others think differently. NOTE, however, that the Euro lamps have fewer problems with poor electrical connection of the base in the socket. You can clean socket and lamp contacts with a common pencil eraser. If you are in a humid and/or salty environment, give a faint poof of Caig contact treatment to the lamp/socket before installing the lamp. Still, the brass bases give more problems, particularly with the K bikes which have sensitive bulb monitoring electronics.
The two lamp sections are:
(1) 12.8 volts, 2.1 ampere, 27 watts, 32 CP, 1200 hours.
(2) 14.0 volts, .59 ampere, 8.26 watts, 3 CP, 5000 hours.
If your average speed is 40 mph, 1200 hours would give you 48,000 miles on these lamps. I doubt you will get 10,000. But, that is normal for any highly stressed turn & brake lamps, stock or not. NOTE: some manufacturer's rate the 7528 lamp high power (brake or turn) section at 13.5 volts and 1.85 amperes, and the low power (RUN) section as 0.44 amperes.
K-bikes: The rear running lamp might be an old #1077, the present number is 5008, and the lamp is 12 volts 10 watts 0.83 ampere. BMW number was 07 11 9 905 337.
The rear brake lamp is rated at 21 watts, 12 volts 1.75 amperes. The present number is 7506. There is another rating, unlikely to be on bulb nor package, and that rating is 25 watts, 13.5 volts, 1.86 amperes. The BMW number is 63 21 7 160 789
Especially on K bikes, but also seen on Airheads, is incompatibility of the socket plating with the type of metal used on lamp bases. The EURO lamps have the proper metal, and it is silvery in color.
Part 6. Back to Airheads information
Osram Miniwatt #64111, also known as Sylvania 39431, and Philips 12023, halogen, 5 watt. This lamp may be OK for use in the eyebrow too, as I've discussed above.
Osram Miniwatt #64113, Philips 12024, halogen, 10 watt. This lamp is brighter than you think, because it will be used in the hole of the headlight reflector.
Osram Miniwatt (number??); Sylvania #64115; Philips 12452; Napa-Wagner 47835; Hella 78165; halogen, 20 watt.
The 64111, 64113, and 64115 all are the same size of physical lamp, they use a Euro base style called a BA9s, and have a 9.3 mm diameter bulb and MOL (length) of 33.0 mm. All of these lamps are nominal 12.0 volt rated. These halogen lamps are not overly common, and prices vary CONSIDERABLY....even 2:1. You can find them by using Google.com by simply entering something like this for a search term: 64111 lamp
There are many possible other lamp substitutions possible for various places on the motorcycle. I have information available on many lamp numbers.
The actual drain and power/light output of a lamp depends on the ACTUAL measured voltage at the lamp itself.
Here is a handy 'quick list' for the various lamps used on various BMW models, that Joe ('Cuda) conveniently posted on the Airlist Feb. 26, 2014....but this list does not include the American part numbers, and I have/do, in this article, in other areas:
2721 W1.2W W2x4.6d Gauges, ~5mm dia bulb
2821 W3W W2.1x9.5d Gauges, ~10mm dia bulb
2825 W5W W2.1x9.5d (not for Airheads, too hot)
2827 WY5W W2.1x9.5d (not for Airheads, AMBER marker)
3893 T4W BA9s Parklight (& GS gauge)
3898 --- BA7s Clock/Volt & /5 (aka A-1272)
5007 R5W BA15s Tail Light
7506 P21W BA15s Turn or Brake
7507 PY21W BAU15s (not for Airheads, AMBER Turn)
7528 P21/5W BAY15d Brake+Tail
7951 R2 P45t-41 45/40w Headlight (/5)
9003 H4 P43t-38 60/55w Headlight (aka HB2)
Part 7. ....more on wiring, lamp life, etc.
Versatile relays that can work fine for most functions in your motorcycle, such as switching lamps, running horns, starting, etc., are the Bosch (now Tyco) 330-073, rated at 30/40 amperes and 12 volts, SPDT, 5 pin, with tab for screw (tab area can be removed); or the Blazer DF005 or DF005W which also has a tab/screw mounting.
There are OTHER considerations:
There are some things not usually discussed about changing the wiring, adding relays, ETC., ....besides the need to do it neatly and foolproof, so that the bike can not burn up. On THAT subject, one must avoid poor connections, bare wiring, places rubbing could compromise the insulation, and, of course, have a FUSE! In almost every instance of adding one or two relays; you will want a direct to battery connection via a fuse. Did you know that BMW, like most vehicle manufacturers, does not generally fuse the headlamp circuits?
BMW could have used larger gauge wires for the lighting, but elected not to. In the following, some is repetitive from information earlier in this article, but is explained differently!
The light output of a lamp is DEcreased if the voltage AT THE LAMP BASE is lower than optimum. Typically, in an Airhead, with reasonably decent wiring, switch contacts, etc., the headlight will see up to ~ 0.8 volt less than the battery terminals will show. This is less voltage than the voltage shown on the fairing voltmeter, if you have one of those and it is accurate (usually they are accurate for the point at which they are connected, which is NOT the battery). Those voltmeters usually show 0.3 volt lower than a direct battery terminal measurement. The decrease in headlight output for a decreased lamp base voltage is quite noticeable, and is one of the two main reasons for adding relays and a direct, fused, connection to the battery. The relays are so-wired that the headlamp can not be turned ON without the key, exactly like the stock function.
Lamps used in vehicles are not all rated at 12 volts. Some are rated at 12.8, or 14.0, sometimes some other voltage. Some foreign, German too, lamps ARE rated at 12 volts nominally, but the WAY they are rated and tested amounts to about the same thing as U.S. lamps, in effect, so I will treat them the same, although they ARE differently rated. Yes, I know that the Europeans and the U.S., has used slightly different voltages on some, at times...but the principal here holds up. The 14.0 volt rating is typically used for lamps that are ON all the time the engine is running. The headlight is a special case though, and is not thusly rated. The 12.8 rating is generally for higher drain lamps that are used only for short periods, such as turn signals and brake lights. These lamps usually have a much higher rated wattage than other small lamps, such as clearance and running lamps and dash lights, and hence will put more of a load on the system, and typically the engine is idling, or soon will be, or producing little electricity from the alternator, and the manufacturer's KNOW that the voltage AT THE LAMPS will thus be quickly reasonably close to that 12.8, and hence that is the rated voltage. I suspect that the lamps are overpowered on purpose, so they are brighter. A case could be made by nerdy engineer-types about the faster lighting-up, or the transient period from higher system voltage to the decreased voltage after a few moments at idle, rather than cruise rpm...but I won't get into that here. The headlamp is a special case, and has complicated ratings, not easily found in specification books.
When you raise the system voltage, whether by an alternator conversion that increases the voltage at idle and above, or, by higher voltage regulator settings, larger gauge wires, relays, etc.....you can expect shorter lamp life. That is the tradeoff. OFTEN the shortening of lamp life is unnoticeable! The DRAIN in watts will also be a bit higher. That is fairly negligible. You may find that all the special wiring and relays, for the stock lamp, do make a difference, but not a great difference. You can find out how much difference light output MIGHT be, before adding relays, etc.... by turning on the headlight, and then ADDING, temporarily, and momentarily, a heavy duty (large gauge, perhaps #16) wire from the battery + terminal.... directly to the energized headlight terminal. BE SURE you identify the correct terminal! Do this at idle rpm, and also do it with the system at an rpm (and battery fully charged) that has the maximum system voltage. You will see the difference. For a truer idea, add a grounding wire of 16 gauge to the lamp common terminal. Be careful! Don't mix up wiring and terminals. If you intend to increase the headlamp wattage size, the effect is even considerably larger. You will probably LIKE the changes!
If your bike has larger voltage drops than normal, you probably need to attend to the various connections, plugs, sockets, even relays and ignition switch, etc. One of the worst places for problems is the red wires connections at the starter relay, and also any slightly loose starter motor solenoid terminal nut that the large gauge battery wire connects to. Other places often having problems are the connections at the diode board......most of them!...but especially the larger red wire connection at the right side of the diode board, as you face it from the front... it must be TIGHT fitting onto the spade. Same for the three stator push-on wires.....and if anal, check the diode board end of those.
Those who are, perhaps, running heated clothing, or maybe some extra lighting, and are running at or near the limits of alternator output, and do not wish to spend the $$$ for a larger alternator conversion, can consider a headlight modulator, which will save quite a few watts (in effect)....besides adding to your safety (and annoying oncoming drivers, or them if in front of you...SOME will undoubtedly say). Those with a lot of additional headlight power and/or heated clothing SHOULD have larger aftermarket alternators.
These clever headlight modulators come from a company called KISAN (KisanTech). They are simple to install, since they are a wafer affair that simply plugs into the rear of the headlamp bulb, then you plug in the regular cable. There is NO wiring to connect to power or ground, etc. The Kisan unit has another cable, that is thin and long enough, it plugs into the wafer unit on some models, and the other end of the cable is the photocell, a Federal requirement. The unit automatically works on only the high beam because of how the plug is made; and, will not operate at night due to the photocell. The photocell circuit has multiple sensitivities and you program the unit, if you have to (usually not), by simply turning the ignition key rapidly on and off per the small booklet that comes with every unit. Directions for the Kisan light sensitivity has varied slightly over the years, so be sure to read the instructions that came with yours. I like the design, obviously, since I have installed dozens. I also can recommend another type, from EasternBeaver.com. That company sells a relay kit that is nearly plug and play...easy installation, and fused too. I do not recommend their standard relay kit for the highest power aftermarket headlights. I am not sure if Eastern Beaver is still selling modulators. Because there are several types of headlight bulbs used on motorcycles, one has to get the proper Kisan model. They handle up to a 100 watt lamp. In operation, you still have the various stock functions of your bar switches. Light output is improved with a headlight modulator only by using a heavy duty relay. You don't HAVE TO do that, however, as the light output increase is rather modest. HOWEVER, if you are using a high wattage lamp (over 70 watts), then it is a must to install a relay, to protect the bars switch. You can do this with one or two Bosch relays yourself, or just buy EasternBeaver's modulator with relays. If just wanting relays on the stock or other modulated headlight, they also have a nice relay package.
Due to a peculiarity of halogen bulbs, your headlight, on the modulated high beam, will probably last longer.
Part 9. Additional Resources, comments, etc.
http://donklipstein.com/That website has a lot of lamp information, SOME REALLY GOOD stuff, and lots of things besides lamps. If you are the really curious type, you may want to read all the sections of that website. Here is one particularly interesting page on LAMPS: http://donklipstein.com/bulb1.html. NOTE that I do NOT agree with some of what is on that website. For instance, he goes into depth on light output, voltage lowering for increased life, etc. His conclusions leave out an IMPORTANT fact ...that you may not care, IN YOUR HOME, if a 100 watt incandescent lamp puts out less watts. THUS, if you are in that category, which he does NOT MENTION, you certainly WILL save money by using a 130 volt rated lamp, running it on 110-120 volts in your home. He makes some conclusions about minimizing costs that are not necessarily true. THESE and some other conclusions, I do not agree with.....but the articles are a very good read!
Versatile relays that can work fine for most functions in your motorcycle, such as switching lamps, running horns, starting, etc., is the Bosch (now Tyco) 330-073, rated at 30/40 amperes and 12 volts, SPDT, 5 pin, with tab for screw (tab area can be removed); or the Blazer DF005 or DF005W which also has a tab/screw mounting. Some relays used on certain models at certain places contain one or two diodes internally. Those can be added, externally, if you do not wish to purchase BMW's $$$ relays.
to 02/03/2003: clarifications: headlamp shell, use of 9003 in /5; minor additions to descriptions; headlamp & eyebrow lamps usage; add socket & harness numbers.
04/17/2003: add .htm title; clarifications here and there.
07/13/2003: /5 large alternator information clarified; add 2825, 2821, and some notes on these types; resources URL's.
09/15/2003: lots of clarifications and includes LED indicators information, more links.
11/22/2003: Clarify 20 watt lamp and part numbers
01/03/2004: revise in several places for clarity, add section on wire gauges, relays, and in-depth lamp life considerations. Add -24 ID to top of article
04/03/2004 : Greatly expand section on side headlight shell information; also add #64198 for /5; edit entire article a bit.
08/25/2004: minor updates, comments on 2825
10/29/2004: add part 3.
07/05/2005: lamp information updated for 64115
03/23/2006: slight updating
03/25/2006: more lamp substitutions for BMW -279.
03/26/2006: final extensive editing
02/07/2007: minor editing, mostly for clarity
01/08/2008: fix URL's; add Eastern Beaver information; and revise the modulator section
06/26/2008: add Osram 64205 information
11/03/2008: add more information on PIAA and other headlamp bulbs
06/21/2009: Recheck article. Minor clarity improvements
07/13/2009: Add hyperlink to article with the federal modulators law
08/28/2009: Add paragraph in two places on lamp sockets and their numbers.
09/15/2009: add a bit more information on the 64205 and 64206 lamps....and later in the day, add more information on high temperature sockets for H4 lamps....and, more, on 09/16/2009.
10/21/2009: Add sketch of H4 lamp base and revise article for more clarity.
12/05/2009: Add Signal Stat information
02/18/2010: clear up wrong or misleading information on the 4 watt lamps; add the -576 later part number.
04/20/2010: remove mbz hyperlink
11/17/2010: Clean up article of typos, extended line lengths in certain places, clarity, etc.
05/09/2011: Add information on Eastern Beaver's ceramic sockets
07/04/2011: Add K bike rear run and brake lamp information
05/13/2012: Add information on headlight specific lumens @ specific voltages, update other areas (minor)
06/08/2012: Expand the section on 1156, 1157, 7506, 7528 lamps, to explain the confusion as best I can.
09/18/2012: Fix typo on 7528 lamps (in one place was listed as 7527) and expand the alternator voltage and current on that 7528, as not all manufacturer's rate it at the same voltage. Add QR code and update Google code
01/07/2013: Add more information on voltage, life, Euro versus USA, and explanations.
05/16/2013: Review and update article.
11/16/2013: Change URL for the H4 lamp sketch, to eliminate a space that confused some computers.
01/14/2014: Add link for HID lamps, from Daniel Stern.
02/26/2014: Add Handy Quick List
09/14/2014: Review. Fix possible problems with understanding voltages at lamp base versus life.
08/13/2015: Add small amount of information on /5 halogen substitutes and a link to chart/sketches/etc.
10/13/2015: Revise and update, almost every area of the article. Reduce SOME redundancies, condense some areas, update certain technical lamp specifications, ETC!
03/06/2016: Metacodes, layout.
08/21/2016: Update article. Metacodes, scripts, H.L., layout, improved explanations, clarity.
© Copyright, 2014, R. Fleischer
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Last check/edit: Sunday, August 21, 2016