Gilera runner 180/172 wont start

I dont know much about bikes but i was riding one day and then the bike just cuttted out then i was told by a friend it was probably the spark plug causing the problem i got the spark plug changed and then the bike started fine after 10 minute the bike cutted out once again i asked a professional over the phone and told him the symptoms then he said it was probably the carburettor and air filter any ideas ?? :cry:

 

try give your carb a clean out mate. and did it still have its compression when it cut out

 

any other ideas even though im still considering the last one