HI, I had a similar probelm with a 2005 Rev 80 and it turned out to be the fuel cock that was faulty. It was the older type of fuel tap that was push pull for on/off .
A bit like yours the bike would start OK then stop and would need choke to start and would cut out then run again.
Lampkins sent me a screw on/offtap and the problem was solved.
