Franco marini engines

[Kilty]

Hey all just joined an john any who heres ma issue nd if any 1 can help TIA I swapped a mini Moto quad for a bike the engine was in bits and doesn’t run I had a friend put engine back together nd I can’t get it working I need the actual model of the engine so I can buy parts I need I think it’s either an s5c or an s6 but I’m not realy sure these pics are the only pics I have of the engine at the moment bike sits in storage along with a few other vehicles