My Gilera SKP 50 won't tick over?

I have got a 1999 2 stroke Gilera SKP 50 which won't tick over. I have cleaned the carb and air filter, replaced the plug and plug cap. I have also tried tuning the carb but no joy. The bike is also using far too much fuel i.e. 1.5ltrs to travel 10 miles!! If the choke is removed the bike runs beautifully. As soon as the choke is reconnected it won’t tick over again. It seems to be taking in air through the hole where the plunger for the choke goes, have tried a new choke this has not sorted it. PLEASE HELP IT IS DRIVING ME MAD!!!!

Thank you

Simon
September 2009