my 2000 honda fireblade brand new batterygoes flat after using it for one day also have another battery that charge up as well and use them on alternate days thought it might be brushes on alternator but it does not have them any ideas thanks

iom fireblade, August 2007

Most likely a failing regulator rectifier, get a multimeter, start the bike, hold it revving at 5000rpm with the lights on Hi-beam, with a new (fully charged) battery you should have somewhere between 13.8V and 14.8V any more/less you probably have a faulty reg/rec. next check is start bike, disconnect alternator wires ( three yellow wires, (maybe a black and red too) hold bike revving (BE VERY CAREFUL WITH THIS TEST!!!!!!!!) and measure with multimeter on AC hi voltage. You should have over a 100v AC between the three yellow wires. if not it might be the alternator. From Honda you are looking at around £500 in parts (ouch!) contact westcountry windings to replace both for less than £200

Andy, August 2007