Vespa px 125 back firing

Just fitted a parmakit 177, pm evolution and a si24mm with polini Venturi air filter to my 2095 px 125! It's sparking but won't start only back firing loads . Can anyone help me out as I'm now stuck and unhappy :-(

back fire and hard starting smacks of CONDENSOR (if you are using points)

That's a 2005! 

Hey Dude,

it sounds like a problem with your ignition.

Wich igntitionpoint you set for your engine?