elecrical fault bike will come on but wont start off start switch but turns over off starter motor but has no spark.

Hi gents/ladies. I JUST BOUGHT A MARAUDER gz 125 to strip down clean up resorts Tec. The only thing is I thought best to start it up first,I put a power pack on the battery lights work ignition light comes on clutch and stand in right positions in neutral but nothing when I press start switch.Turned engine over off starter turns well but no spark I am wondering along the lines of cod unit or am I way off the mark. I am 47 and this is my first ever bike any advice will be appreciated. Thanks Gareth.