Early this riding season  My reg./rec. failed . The style (a Y wound alternator with 3 ungrounded legs, and a reg./rec. that sheds extra  power to ground by releasing it as heat-thru the blades found on it's surface)  it turns out,  is standard use on about 90% of all motorcycles , only differing in output ,governed by the power needs of each bike, like lighting ,ignition , accessories and battery size.
    While  I haven't found in print anywhere,  the output of your alternator in DC amps ,  I will ASSUME that it is at least 10 amps ,and that the voltage level is around 14 volts. These assumptions are based on factors such as ; to charge the battery the voltage has to be higher than 12v or the current wouldn't flow to it, and after riding to the point the battery is fully charged ,a reading across the battery poles is in the neighborhood of 13.5 volts  ( if the system an battery are in good condition) and the fact that the resistance of a 100ft. of copper wire is about .36 volts.       The fact that the ignition draws very little power, as does the decomp timer ,  turn signals , neutral light and brake light are not on continually ,I have discounted altogether , but all the rest of the lighting systems is , with low beam on it draws 7.5 amps / high beam 8 amps . normal charging rate of a new battery is said to be max. 2 amps , bringing the needed output to around 10amps.(any added power can be provided by the battery with it's 220 cca)
   I am guilty of using LED turn signals ,but they have little affect on my system.  Where the use of LED light can provide better lighting , and last much longer,  the power savings can become a two way street . If you plan on adding additional accessories the power saved can help. I didn't ,so I stopped .  Being that when the battery becomes fully charged ,the regulator needs to dump power,  it heats up , in the stock bike it needs to shed only about 2 amps,  however if you also use an LED headlight which draws about 1.25 amps  ,now  it needs to shed another 4.4amps  ,or a total of 6.4 amps ,  over 3 times  the heat it normally sees.  Heat is hardly a friend to electronics.
    If you intend to use LED's I would urge you to check out regulator /rectifier s that use  Mosfet Technology  these rid the same amount of power, with a decrease of 50% less heat ,  with a cost of a stock regulator from Suzuki , and work with the same type system that  the Savage and most bikes do.

I don't believe the the LEDs means that the regulator has to work MUCH harder, probably just a little bit. I suspect that the unregulated output from the alternator can reach well over 100V AC and just as you say the regulator shunts everything above a certain voltage (usually just over 14V DC) and dumps is as heat.

In my experience just because something CAN supply 100A doesn't mean that it "prefers" to do so. Heat generated is normally a product of resistance and current flowing through the circuit. If the alternator and regulator has a resistance of 1 Ohm and the load is 10A and you change the load to 1 A you only have 10% of the original heat losses generated.  (This was kind of a bad example since 10A over 1 ohm would generate a voltage drop of 10V but you get the idea).

My point is that below the "shunt voltage" of the regulator the load is LESS than it was before meaning that it will generate LESS heat than before. And when the regulator starts to regulate it still shunts the the same voltage through the same wires so I doubt it would make it much worse than before.

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Just realized I have the parts necessary to measure the current going through the three wires from the alternator. I recently calibrated a three phase current transformer to use with a large electrical heater in my brewery. With the oscilloscope it's fairly easy to measure the current going through the wires with the lights on or off.

I have modified my bike and it uses LED's for everything, and it no longer has the electric decompression solenoid....the bike starts within a couple of revolution and I suspect there is very little battery charging needed.  The headlight is currently a Cyclops H4 that is claimed to be 38 watts.  The tail light, instrument and license plate lights use very low current.  I also have a Lithium Ion battery.

So far I have gone 10,000 miles without an problems.  Part of this may be that my rides are limited in length on this Cafe' conversion, and most rides are less than an hour in length.  I may ride all day long.......but there are lots of stops where the rectifier may be able to cool down.  The rectifier is mounted to a steel plate as a heat sink just like the original steel fender provides, and it is in a place that gets good air flow.  Most of my riding is done with the engine in the 3,000 - 4,000 rpm range.

It well could be that if I was riding long distances between stops I could experience "heat stroke" as a result of the smaller electrical load.....but so far no issues.

Batman:  With 37,000 miles on your rectifier....maybe it just got tired and would have failed with the stock bulbs in place?  There are numerous reports that the stators fail over time.....the engine heat evidently breaks down the insulation over time and they short out.  

Failure of a reg/rec  Is not something that is going to happen overnight , I wouldn't even go so far as to say that because in the example I showed that  had to shunt 3 times as much power that it means the thing will die 3 times sooner ,just that when you start adding LED's  conditions change a bit faster than you might be aware of .  You might consider for a moment ,what the extent would be if you change your whole lighting system to LED' s. Vercy's move to a mosfet reg. decreased his risk by 50% , adding a few running lights to your bike ,could do the same.  My bike is 24 years old , did the reg. die from mileage  or old age?  Either way I'm not complaining. It's just like the petcock or plug leak , If you keep the bike long enough it's going to die ,you just have no clue as to when.

bolted my rectifier to a thick block of aluminum, bolted the block to the frame using the fender bolt holes. no fender.

I was thinking of mounting it under the headlight and running longer wires. Never liked it under the seat. It would also make more room for the soft saddle bag attachment under the seat.

 What periods of low current (amps) are you talking about ? the minute the bike starts it draws 7.5+ just to keep running ,  not counting the amps used to recharge the battery you just drew down to run the starter  The power being put out by the stater is AC  the  rectifier changes it to DC  ,that's when the heat is released , up to25 % of the power is lost to heat in the conversion.  Research a full wave bridge rectifier and learn how it works,  and that is before  extra power used fully charges the battery and is shunted to ground (more heat)


Our alternator has permanent magnets if it's turning it's  generating , the only time there is a slight reduction of power is at lower rpms, and a slight increase at higher rpms .  100 volts AC at 5000 rpm is merely a test point , I doubt most of us ride at 5000 rpm that would be equal to 75 mph. There are no periods of low current.

I'm glad I checked in today. I was just thinking of installing a new LED headlight bulb...possible a tailight too but not blinkers.
Would just the headlight/tailight in LED cause a problem for me?
thx