I have had a 2008 YZ450f since it was new. The bike developed a killer bog while under throttle during the last ride. I pulled the carb and cleaned it. Pulled exhaust pipe. Disconnected the throttle position sensor, and kill switch. I also took the air filter completely off. All of these changes had no effect. The motor will start within one or two kicks. Then rev cleanly to almost 1/2 throttle. Then it falls on it's face so bad it will kill the motor. The jetting is the same as I have run since the last rebuild. Nothing found in the carb. The bike sounds way too rich but removing the air filter has no effect. Has anyone had ignition box or stator problems with these bikes?