Alternator fuse blows with lights on!

[Tonybloke88]

Yesterday I became the proud owner of a 2003 660 Bagira... but sadly it seems to have an electrical fault. If you ride it with the lights off then the battery charges fine but if you turn the lights on the Alternator fuse blows and the after a few miles the battery goes flat and the bike stops.
I've spoken to a couple of mates who have heard stories about water getting to the head light and causing a similar problem but the bike hasn't seen any rain for months and its bone dry.
I suspect that there is a short somewhere in the side light curcuit but I was hoping one of you knowlegable chaps could point me towards any typical places where this has occured in the past.

[DAVID THOMPSON]

the mz bikes are bad about crosion in the plugs that connect the
wireing harness together check all connectors also
there may be a short in the switch its self
the harness on my rt125 is made from very small wire
and they were not run to the lamps very good some were
streached tight and had a place rubbed

i would take the head lamp apart and inspect all the wires

[phlat65]

look for a rubbed through harness at the headlamp bracket. also, any place the harness runs near a removeable part, like the tank or seat. has the rear fender/light combo been modded? I did not know you could run the bike with the headlamp off...

[DAVID THOMPSON]

a 100% inspection of all the wires that get power when the lamp is turned on and check
and make sure someone has not installed a super high power bulb in the headlamp
the bmw riders here(USA) were buning up the handlebar switchs
with H4 100watt bulbs way back in 1978
the wires in my saxon tour will handle a 60 but no way would i install a 100
watt
also inspect wires that run to and from the key switch a site user said
he had wires come loose from back of switch causing unnamed problems
and site member jayded1 had a 125cc sx with a bad key switch
blowing fuses

baggie wireing drawings can be emailed on request
pm me a good email address as i can not post them here as i am out of room

the usa requires lights if on the street
some countrys only require a head lamp if used after dark

a question for uk riders is it possible for a uk street bike to pass mot insp
with no headlamp if used only in daylight

[Tonybloke88]

Thanks guys for your helpful comments I eventually found a wire on the supply to the rear light that had been rubbing on the body clip for the RH side pannel. A quick repair and job done

To answer your question: yes we can ride bikes over here with just a brake light but they are restricted to day light use only but with the on going invasion of the European nanny state I would not be supprised if that changes soon

[keithcross]

Tony

For a daytime MOT in the UK, you do not require any lights at all. This is to allow compitition bikes for Trails and Enduro events access to road sections. A few of the motosrd riders I go on runs with dont have any lights fitted, so you have to give them plenty of room.

Keith

[DAVID THOMPSON]

man a brake light would be nice so you dont bang someone in the arse

my homemade 1964 bike a royal enfield frame with a briggs & stratton engine
had only a brake lamp and was retired in 1968 when inspections
required full equiment