New purchase with electrical issues.
 

Hi All, Just got a 2003 f4i. Mechanically excellent but has electrical issues. Went for a ride - did about 20 miles and it stopped. The battery was fried, hot and bulging. A mate put another battery on it and the bike fired up great - charging at 14.3v. Off to home but fried his battery as well so I owe him one. Anyone any idea of the problem. I am assuming a reg/rectifier problem as I have heard there can be a problem with them and an upgraded one can cure the problem? In addition, the headlights sometimes come on with the switch and then maybe not - dirty switch or is this another known problem? Before ripping the wiring apart, any ideas what could be the problem? Just going to look for a manual so I can check the relevant wires etc, hopefully this will give me some clues but members knowledge is always better.. Many thanks for any idea's. Peter

Hi and welcome to the forum. The R/R is a good place to start. I'd put a meter on it and see what the voltage does while riding. Nothing wrong with 14.3, but if it climbs at higher RPM's, then R/R is likely the issue.

hi. i think bulged battery is usually caused by overcharging. how long did you check the charging ? i would suggest to check charging in different RPM ranges for a couple of minutes.

it could be a dirty switch. you can spray some contact cleaner there and check if it works well.