Dustin. Great thought but i ve run engines, although not This perticular engine, as mines still only just broke in most the way and still in my CT5, on the test stand with no flywheel without issue. ofcourse this is just to check that the engine runs and will idle ok after a carb rebuild/head gasket or teardown and clean ect. and to check for air leaks. its easier to see/hear them when the engine is open and fully visable... see, this is why this flywheel issue puzzles me so much... i ve ran through the most probable reasons and the 2 i listed are the only likely candidates.. things that make ya go hmmmmm.
Tim