I have a 2002 Wr426 that has always started 1st or 2nd kick hot or cold. The bike is street legal and I have jetted it to run great for many years this way. Recently, It started to need the choke to start when warm or hot (will start first kick with choke). It runs perfectly when started. I have checked the valves and they are in spec. New spark plug. Checked carb and jets are clear. Any thoughts on what might be causing this?