Suzuki has 2 "thrust adjuster" assemblies, they hold the gsxr engine in place, register the engine left right, they are located lower behind the engine. in order to remove replace a gixxer engine you need to loosen these. you could buy Suzuki tool 09940-14990 for $70.00 or:

-remove top standard fastners (14mm)
-make tool to fit the thrust adjuster locknut:
-get a used deep 22mm socket, 12point
-every 4point of the 22mm 12 pt socket make a tooth, 4 teeth 90deg apart
-cut the teeth with a dremal tool, 50mm wide and 50mm high
-round the top corners to match shape the the locknut
-remove the thrust adjuster locknut with the tool, should come off easy

the engine thrust adjuster is exposed

-a 6point 19mm socket will slip over the adjuster unthreaded portion
-the adjuster should loosen easy
-the engine is free.