You're running the bike really lean. That's why the tip of the spark plug is white. The electrode didn't touch the piston. The gap on the plug has closed up from detonation. The detonation is caused from running really lean. Like mentioned, do a leak down test. If you're lucky, you'll find an air leak but not have damaged the motor. Most likely, you've started to damage the piston and now have no compression.
Leak down test first to check for leaks.
If it passes the test then check your carb to make sure it's clean and properly jetted.
Report your findings here.