Fastest I ever got an engine out and back in was with an old Fiat 850 Spider (I should be embaressed to admit to owing one). Had a good friend and we pulled the engine with no lift, just unbolted it and I leaned over and hauled it out. Then replaced the leaking oil pan gasket and the screwy pulley and set it back in place.
Lapsed time was 2.5 hrs. Of course that engine is no bigger than what an average motorcycle will have. Hardly any bolts to hold it in either.