Title says it all... on my GS... Its regulator is fine... I know cos I swapped it from a different bike, and the bike did the same thing. Also it makes 13.8 volts at idle, and 13.2 at 5K rpm when measured at the battery.
Cool.
Srinath.

<snicker>
Because your forks compress under braking and the headlight is pointed lower at the ground.

</snicker>

Mine did the same thing until I installed the LED taillight.   How low is your idle?  I think Mine woulden't dim if it was above 2k but anything below 2k and it would dim.  See if you can get lower wattage taillight bulbs or something.  If I think about this right, the taillights are 25watt bulbs.  and there are 2 elements in each one so when your brakes are on its 100w of power being used.

Put on the choke or hold the idle higher and see if it still does it, (I bet it wont)

Yikes... OK I'll try to rev up and see if it does it. And no  :guns:  JamesG... Not braking while riding and it hits the ground ... I was standing in my driveway with the light pointed at the door and it got dimmer not lower.
Cool.
Srinath.

you're dropping voltage at higher rpms - do a stator test. I know from older gs's i had these "stator papers" are pretty useful. When you rev voltage should increase.

http://thegsresources.com/garage/gs_statorfaq.htm#charging%20circuit%20is%20OK?

that's not a problem....if it's bugging you then raise the idle...every small engine bike does that because the tail lights take away some power...

just like when someone has a crazy sound system in their car, every time the bass hits the lights dim (if the alternator is stock)

If the bike is at low RPMs, then the effect should be about the same whether the engine is running or not (R/R is producing lower voltage than the battery, so will not contribute).

The taillight and headlight will both be drawing amperage at whatever voltage the battery is supplying.  If the headlight dims when the brakelights are lit, that means that the voltage supplied by the battery is dropping with the added 25w of draw.  

Crummy bike batteries.  Anybody want to replace their airbox with a relocated unipod and try fitting an automotive battery (like from a Metro) into the battery/airbox space?

My battery is a sealed bike battery... pretty good. but of course not as good as a car battery. BTW A metro's battery is still too big to fit between the frame rails... the Best battery would be a lawn mower batter, but that is rather deep and youy need to remove the battery box and the bottom bridge which the rear fender bolts to.... and make up a sorta tray etc to fit it there. I think its a bit of over kill though. Bike selaed batteries work just fine.
Cool.
Srinath.

Poor connections can also cause unusually high current draws and/or voltage drops.

It's a ritual amongst old BMW riders (the bikes, not necessarily the riders!) to clean terminals and ground connections. Old wiring harnesses can have corroded contacts in the connectors, corroded wires inside the crimps, and the ground contact areas can corrode.

Start at the battery and clean contacts and even replace the high current wires and contacts if possible. The contacts can lose their spring force. Go up a gauge or two on the high current wires - saves a volt or two by the other end of the harness at high current draw.

Damn, Srinath.....you might actually have to WORK on your bike.  Adding oil  and cheap tires probably won't fix this problem..... :nana:

I think Kevin might be on to something, from a purely electrical standpoint, increased current draw past a point of high resistance, causes more voltage drop at that point.  This would have to be a point common to both circuits though, such as battery connection, as pointed out above.


When you hit the brake, more current is drawn, and thus more voltage would be dropped at the bad connection.  One of the leading reasons houses burn, unlikely to happen to your bike however, so don't panic, yet.   :mrgreen:

<--- Sparky

DOOHH!!!    That was cold  

You obviously have NEVER seen Srinath's bikes.  

think RAT BIKE          but....uglier

ya may be thinkin' "ugly rat-bike-thing", but hes got like fifteen million bikes so..........    :dunno:  :mrgreen:

i might have a few more bike than him....18-20 or something like that......
also just bought a vintage race car today (1965 FORMCAR FORMULA VEE...I think? )......TOYS are SOOOOOFRIGGIN'KEWL

none of my bikes are pretty either, most of them are cobbled and taped together basket cases. but they are paid for.  the V65 sabre needs a home and the GL1000 needs a funeral. the 440 might need a new rectifier dont know yet, but runs if jumped. as i have torn down my GS engine 3x in 3 weeks and have gotten damn quick with it.(yes, and that includes still driving it to work for the week as tear downs were on days off)   still dont look any prettyer and might be getting a 85 GS550ES for the price of dirt, seen it run alittle last year, carbs need cleaning, petcock needs O-ring, and tires.  2nd gear is alittle dodgy but after my GS engine, it dont scare me no more to open an engine/tranny. or i could just ride around 2nd, been doing that with my yamaha for some time.

Quote from: seshadri_srinathMy battery is a sealed bike battery... pretty good. but of course not as good as a car battery. BTW A metro's battery is still too big to fit between the frame rails... the Best battery would be a lawn mower batter, but that is rather deep and youy need to remove the battery box and the bottom bridge which the rear fender bolts to.... and make up a sorta tray etc to fit it there. I think its a bit of over kill though. Bike selaed batteries work just fine.
Cool.
Srinath.

If you try hard, a miata battery (the original panasonic AGM battery, not the wet-element replacement that the dealers sell) may fit sidewise if you ditch the airbox. You still need to fab some sturdy tray 'cause the battery is f***ing heavy, and replace the connectors.

My GS wiht the Body set I got from KevinC is actually quite pretty. Not rat bike pretty... pretty as in getting the "occassional nice" bike pretty. It does have that nasty oil leak, and some serious dirt on the wheels from the chain and brake dust in front. I dont shine them up but they are usually free of issues. And no I dont run out an replace parts at random when I see a problem. I usually diagnose it quite at detail and find the actual problem, why it happened and how to prevent it for good. I'll post a pic on the bike.. I have been wanting to... actually... I believe I have made the nicest looking triple/dash/guages setup.
Cool.
Srinath.