peugeot speedfighter runnin badly?

hi i have a peugeot speedfighter 2 and it just stopped workin one day i was riddin it and it just started not ridding properly and then when i was trying to start it was just startin on full revs but dying a few seconds later and i had my friend come look at it and he said theres not a great spark there or something can u tell me if its cdi or coil or the immobliser i only have a black key though no red ones apart from the trelock keys thanks pleeze help if u can