Severe bogging at 2 mile mark - 95 500 Carb

I would welcome any suggestions for my 95 500 Carb machine that works well when cold and at about the 2 mile mark, severely bogs down. Engine will continue to run but will not engage the clutch. If I let it sit for awhile and it cools down, I can start it and run it for about 2 miles and then then severe bog again. This occurs almost like clockwork.

I have done:
Change plugs
Cleaned carbs
Checked spark
Clutch: Seems in good working order
Choke: Start well. With 1/2 choke when warm will kill engine.

Thanks for your feedback.

Severe bogging at 2 mile mark - 95 500 Carb