1990 k75 ok so my battery was dead so i try to
,il help you on this one,,,,so long as you dont try this again,,,ok!
first lift the fule tank to get to the relays under it in a black box,,,
take the lid of the relay box and look inside it,,,you will see a long black relay that is bolted down with a 10mm bolt and with two battery leads going to it near the seat end of the box,,,give this relay a jentel tapping with a screw driver,,,this relay is the starter relay and,,,,(its stuck in!) you have "welded the contacts together in it!" if it dont let go then its a new relay,,,and thats pricy!!!! £70???+!!!
thats what happens if you try to jump start a bmw!!!! with to fuw amps to turn it over!!! keep tapping the relay till it lets go and you can then hook up the bike's battery after you have "fully charged it first"!!!! so its got the amps to turn the motor over with out welding the starter relay up again,,,heres a tip,,,if your going to leave the bike standing around not in use get yourself a 2.5watt 12 volt solar battery charger and hook that to the bikes battery it wont over charge the battery but it will keep it toped up and fully charged,,and all it needs to work is good light,,,
see free power??? now go off and fix this bmw,,,easy realy?
and dont try starting her up on a car charger,,,use a car battery if you must,,but not just a charger,there is to fuw amps in it to start her up!!!