What Driving Light For Engine Guard Mounts?

[captmako]

I've seen pics of Airheads with a large single driving light mounted on the top of engine guard. What are those lights?
Look slick in my humble opinion. Might have to add one for my evening soirees.

[PITAPan]

I've seen pics of Airheads with a large single driving light mounted on the top of engine guard. What are those lights?
Look slick in my humble opinion. Might have to add one for my evening soirees.

Think, cheap ones. Not a protected location. Look into the Hella 500 series.

Personally I don't like big light down low except for rain and fog. You don't get a good look at the road---to judge the surface accurately the lights should be as high as possible. But I agree, they look cool and all rallyish and whatnot.

[Ken in Oklahoma]

I've seen pics of Airheads with a large single driving light mounted on the top of engine guard. What are those lights?
Look slick in my humble opinion. Might have to add one for my evening soirees.

If and when you go to select your light, do keep in mind that the airhead charging system is limited. I believe that no stock airhead charging system is rated at more than 240 watts (20 amps at 12V). Also demanding more power from your charging system is harder on it, even if within the rated capacity. (And It is also entirely possible that your stock charging system will have a happy life forever and ever.)

To be clear, I'm not saying you ought not do it. Only you can weigh your needs vs any added risks.

Ken

[captmako]

I've seen pics of Airheads with a large single driving light mounted on the top of engine guard. What are those lights?
Look slick in my humble opinion. Might have to add one for my evening soirees.

If and when you go to select your light, do keep in mind that the airhead charging system is limited. I believe that no stock airhead charging system is rated at more than 240 watts (20 amps at 12V). Also demanding more power from your charging system is harder on it, even if within the rated capacity. (And It is also entirely possible that your stock charging system will have a happy life forever and ever.)

To be clear, I'm not saying you ought not do it. Only you can weigh your needs vs any added risks.

Ken

Ken, how many watts does the stock airhead (mine is '86 R80 - naked) use running with lights on? I surely don't want
to overtax my stock system. Thank in-advance.

[PITAPan]

I believe the stock "big" system came out mid /6 @ 13.5V, 280 watts, 20.74 amp. look at the sticker on your diode board.

You can't "overtax" the charging system. if you have adequate cooling (some of the full faired bikes didn't) you can run the charging system maxed out forever. Probably get slightly greater wear at the alternator rotor commutator/brush interface. The rotor will break before it wears out anyway and brushes get replaced every 100k+- (miles) or so any how. I've run them at max for 20+ years. Replaced brushes in there somewhere. I do clean my commutator every so often.

BUT, if you exceed what the charging system can put out you draw down the battery. The battery will take up the slack for as long as it lasts. I'm doing this currently with a single 130 watt headlight and a dual plug electronic ignition. I slow down at night but I'm still spinning fast enough to get max charging (close to 4k). The large battery on my LWB /5 and /7 will take it all night. Always charged it when I got in so I can't say about just how low it got.

The wiring will take it, if it won't the fuses blow (they better!). With all lights, running them on relays and wiring a feed back to the battery with hefty wire is strongly suggested. More light for your watts, switches last longer, simpler wiring in a certain way. I use one feed, 10 Ga. marine wire to a pair of fuses and a pair of relays for the headlight. I'm hard wired because of the heat sink on the back of the bulb holder and a lot of other changes. Soft wiring (no changes or taps to stock harness) can be advantageous and is extra easy to set up, easy to diagnose and gives quick back up options in case of switch, relay or wiring fault. Eastern beaver has come out with a nice soft wiring kit. You can also just make your own for a tiny fraction of the EB price.

\BTW, the power to make all those amps comes from somewhere, namely your crankshaft. I used to have a VW with a major lighting setup. If I hit them all you could feel the poor thing slow down.

[Ken in Oklahoma]

. . . You can't "overtax" the charging system. if you have adequate cooling (some of the full faired bikes didn't) you can run the charging system maxed Iout forever. . . .

I didn't say "overtax" the charging system. I said in effect that running at maximum capacity can be "hard" on a charging system. And I'll stand by that statement. That a charging system may be running within specified parameters doesn't negate the fact that "elevated" temperatures are harder on electrical and electronic components than lower temperatures. The prime culprit, if we should call it that, would be the diode board, and within that the high current diodes. There's a reason why high current semiconductors usually have heat sinks. The stock diode board diodes are heat sunk, though it isn't the obvious finned extruded aluminum chunks that we are used to seeing on higher power audio equipment. The diodes in our airhead heat sinks are press fitted into a steel cage which is a heat sink, though not as flashy or as efficient as the extruded aluminum types.

The rotor failures, I believe, are primarily mechanical failures of the windings or the attachment of the windings onto the slip rings. There is the obvious centrifugal force as well as the less obvious "squirming" that the windings do with the heating and cooling cycles. And so, yes, the primary failure mode will be that the rotor "breaks". Typically a rotor works until it suddenly doesn't (though I guess the same could be said of the diode board as well).

The diode boards are in a particularly tough environment what with being enclosed in that aluminum engine "shell". And as you indicated a fairing, especially those with the "solid" lower center piece, makes matters even worse. Supposedly there is some cooling of the diode board via vents in the front engine cover and with the "back end" of the diode board being somewhat "exposed" to the starter cavity, but how good can the cooling be with the engine running at, say, about 180 degrees there.

In my post I was careful not to over emphasize potential problems running at full capacity as being disasterous to a charging system. But I would not go so far as to say that a charging system being run at full power would have no impact on charging system durability. In the limit the rating of the charging system, including the diode board, was set by a team of Bosch electrical engineers aiming to define a (by definition) arbitrary allowable load.

Ken

[barryh]

The wiring will take it, if it won't the fuses blow (they better!).

Don't count on it !

Fuses do provide protection to the wiring but only against short circuits or significant overload. They don't generally protect against minor overloads. The problem is that fuses are relatively crude devices. A fuse will take it's rated current forever and modest overloads of 10% possibly forever but at best for something like 100 hours. To get a fuse to blow quickly in say less than a second the current has to be something like double the fuse rating.

Electrical fires can be quite spectacular. I learnt this the hard way in the early 70's when a short circuit on a Triumph Bonneville rapidly turned the wiring insulation into smoke. Cause of the fire was not the short circuit, it was the fuse rating or should I say the lack of. When a fuse blew in those days many riders had a ready replacement on hand. All you needed to do was wrap the fuse in some silver paper from a cigarette packet.

Very Marlon Brando but not very bright !

[bbelk]

When a fuse blew in those days many riders had a ready replacement on hand. All you needed to do was wrap the fuse in some silver paper from a cigarette packet.

A 22 caliber bullet fits very nicely although I have heard there may be some drawbacks to that design as well.

[PITAPan]

. . . You can't "overtax" the charging system. if you have adequate cooling (some of the full faired bikes didn't) you can run the charging system maxed Iout forever. . . .

I didn't say "overtax" the charging system. I said in effect that running at maximum capacity can be "hard" on a charging system. And I'll stand by that statement. That a charging system may be running within specified parameters doesn't negate the fact that "elevated" temperatures are harder on electrical and electronic components than lower temperatures. The prime culprit, if we should call it that, would be the diode board, and within that the high current diodes. There's a reason why high current semiconductors usually have heat sinks. The stock diode board diodes are heat sunk, though it isn't the obvious finned extruded aluminum chunks that we are used to seeing on higher power audio equipment. The diodes in our airhead heat sinks are press fitted into a steel cage which is a heat sink, though not as flashy or as efficient as the extruded aluminum types.

The rotor failures, I believe, are primarily mechanical failures of the windings or the attachment of the windings onto the slip rings. There is the obvious centrifugal force as well as the less obvious "squirming" that the windings do with the heating and cooling cycles. And so, yes, the primary failure mode will be that the rotor "breaks". Typically a rotor works until it suddenly doesn't (though I guess the same could be said of the diode board as well).

The diode boards are in a particularly tough environment what with being enclosed in that aluminum engine "shell". And as you indicated a fairing, especially those with the "solid" lower center piece, makes matters even worse. Supposedly there is some cooling of the diode board via vents in the front engine cover and with the "back end" of the diode board being somewhat "exposed" to the starter cavity, but how good can the cooling be with the engine running at, say, about 180 degrees there.

In my post I was careful not to over emphasize potential problems running at full capacity as being disasterous to a charging system. But I would not go so far as to say that a charging system being run at full power would have no impact on charging system durability. In the limit the rating of the charging system, including the diode board, was set by a team of Bosch electrical engineers aiming to define a (by definition) arbitrary allowable load.

Ken

are you serious?

[ME 109]

are you serious?

You better believe it.
And you'd better not call him Shirley either.

A driving light on the crash bar gives excellent light. A driving light on each crash bar is mo better.
For cool, a 4" sealed beam with a chrome mesh protector grill is tops, especially with a nice domed chromed body.
Those were the days.

My next light will be a 'ridgid industries' roo fryer. Maybe two.
http://www.rigidindustries.com/led-lighting/50111

Best mounted off the crash bars on a faired bike, so there's no light wobble.
Off the handlebars/top end is good for an unfaired bike.
Standard /7 lightmachine will accommodate a 100 watt H4 for most people, unless your an interstate trucker with heated vest, gloves and underwear, driving all night.
But if you are, go led and you're set.