Ok is it the RX?
Is the kick start nice and smooth has it changed any in its feel. Not getting a bit stiff when you push down?
First thing I would do would be strip your carb down and see if there is any water in it. I would then pop a new plug in and air filter.
Is it standard or have you added any trick bits of late. Was it running fine before and when did it start to happen?
bb
March 2010