suzuki GS400--misfire when lights on

[Guest]

Hi,somtimes when i turn the lights on,the engine misfires on my Suzuki GS400,misfires no matter if its raining or is sunny.
Do you guys have similar problems?can you give me some ideas how to fix?
Thanks.

[Brendan W]

Gut reaction is that the voltage seen by the coil is marginal and with the lights on the voltage falls further causing misfiring. Ideally it should be about 0,5 Volt below battery voltage.
The first thing I would do is clean the supply plug to the coil followed by the kill switch internals, the fuse box, the ignition switch internal contacts and all the regulator/rectifier connections.
After that it's time to start measuring the charging system performance - see the sticky at the top of the electrical connection.
Get measuring and get back with the numbers.

[Andy24]

Ill try cleaning all the connections and will see,thats happens maybe 2 times a month...but irritates me cause can happend at night and i cant go anywhere with a misfiring engine or with no lights.