Ive had a constant problem with my CBR250R, ive noticed that sometimes it likes to spontaneously die while the clutch is in and youre sitting at the lights but this only happens when the engine is warm. Ive been riding it to work and its fine for the entire journey untill i pull into the carpark, pull the clutch in and just roll down the hill. As i do this it seems the engine just cuts out after a few meters of rolling. Its also been having a bit of trouble starting when its warm which i assume is part of the same problem. The only way it will start is if there is a bit of throttle on when trying to kick it over and even then i can sometimes feel a distinct lack of power as i try to rev it. As in, it kicks over and i roll on a bit more throttle, it revs then starts to lose power untill it cuts out no matter how much im revving at the time. Ive had a spark plug and oil change. Im not too sure what it could be, any help?