my speedfight 2 is making funny noises!?

it only happened today so i haven't asked a specialist blokey yet, but...
I tried starting my NEW peugeot 100cc speedfight 2 and it made a load of noise and sounded like it was abut to explode! i didn't know weather to just keep reving it or what...
it was a crunchy noise... i am not sure weather something is loose or anything...
i work on the seafront so i was wandering if some sand had ot in something somehow... wot do i do?