started bike. all fine, but will not turn off, untill I undo the earh strap, what"s going, anybody??

 

Engine or starter motor?

 

Engine!!

 

Not sure if the 300 was AC or DC ignition. Assuming it is AC, there will be two switches inside the ignition switch, one sends power from battery to anything needing live with ignition on, the other switch earths the CDI to kill the spark, (some work the other way round, earths the CDI to enable a spark). So either that part of the switch isn't working, or the wire from it to CDI or earth has come adrift.

If it is DC ignition, this works by sending battery live to CDI via the ignition switch, so switch off and it should cut power to the CDI, which again would point to a faulty switch.

 

Cheers, will check the switch and let you know how I get on