We have 2010 250f that became hard to start, had to bump start fist time each day then would start normally. Valves fine all within clearance. Then becomes almost impossible to start, only bump start in 1st gear and would not idle, had to hold gas on to keep running. We have progressively done the following: 1. checked valves 2. checked cam timing, cam has been welded and cam has not slipped on gear 3. replace fuel pump (we have also swapped fuel tanks with other running bikes) 4. From a new bike we have progressively swapped every part including the wiring harness, throttle body, coil, capacitor, rectifier, fuel box, plug cap, spark plug etc. 5. swapped compete left case with stator from a running bike The bike has spark, the fuel pump is pumping fuel when the bike is kicked over but plug is not getting wet. When kicking over it at best will have small backfire intermittently. We have swapped heads . When head was off cylinder looked good. Bike has 10 hours on it. Will be pulling flywheel to see if sheared the woodruff key. Any ideas would be helpful.