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:/ the H4 you linked to draws 45 watts on either high or low beam, assuming only one filament is on at any time … that is still higher then the current draw from your original bulb. The relationship is watts = amps times volts

So at 45 watts and 12 volts your amperage will be 3.75 amps, where it was previously (35/12=2.92) 2.92 amps I'm going to take a wild guess that your headlight fuse is a 7 amp fuse and that should suffice, unless both filaments are burning which would draw 7.5 amps and cook a 7 amp fuse. … there is a high beam indicator lamp in there somewhere too, but that's not very power hungry.

Your electric starter is by far the highest power consumer on the bike (heating elements and motors have much higher power requirements then incandescent lights)
If your lights are on when she starts, this might be a problem for your battery to keep up with, then your alternator and it's associated rectifier will be stressed.


Need more input :| is the headlight on when you hit the starter button, and are both filaments cooking when it's on high beam ?:I … there has to be at least 35 guys here that know the answer to this.
 
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