2003 yzf450 wont run right?

Honda HR21 lawnmower would start and run for about 5 seconds, then die. Pulled tank, carb, air filter and plug. Cleaned everything thoroughly, re-gapped plug and filled with fresh gas. Motor has good compression. Now it starts and runs great on low, medium, and high throttle settings. After warming the motor up for aprox 5 minutes, I try to engage the blade clutch (motor on high, and it kills the motor, every time. If I over rev the motor manually (past the governor setting), the blade will start and seem to operate normally but when I let the motor fall back down to the "normal" full throttle rpm setting, the motor dies. It's as though the motor needs to run faster than full throttle (on the governor) for it to start the blade and keep it going. Thank you in advance for your reply. Honda HR21 lawnmower would start and run for about 5 seconds, then die. Pulled tank, carb, air filter and plug. Cleaned everything thoroughly, re-gapped plug and filled with fresh gas. Motor has good compression. Now it starts and runs great on low, medium, and high throttle settings. After warming the motor up for aprox 5 minutes, I try to engage the blade clutch (motor on high, and it kills the motor, every time. If I over rev the motor manually (past the governor setting), the blade will start and seem to operate normally but when I let the motor fall back down to the "normal" full throttle rpm setting, the motor dies. It's as though the motor needs to run faster than full throttle (on the governor) for it to start the blade and keep it going. Thank you in advance for your reply.

I have a 2003 super glide that is hard to start and the choke doesn't work. sometimes it backfires through carb I have a 2003 super glide that is hard to start and the choke doesn't work. sometimes it backfires through carb