How start my rebuild 180 sp?

Hi ive had my engine rebuilt fully and now put back into the bike, now the main question why wont it start? Basically when im checkin over the only problem is thers no petrol going in to carb ive try to suck the tube to get petrol flowing but only little drips coming thru how can i get thet to flow properly and is ther a chanceit could be frozen its sat out in the cold for ages the engine been inside my house but maybe could the tap be frozen or anyfin its not that cold outside but cold enough to freeze ice over in a bucket of water in my garden not thick layer any ideas please help ive had my bike since i was 17 and now 22 but has sat around for years were i never wanted to sell and never gonna sell its got spark its got compression, but i did fill the gear box oil to the top and got some out but could that be a problem please help