Yesterday I purchased a leak down tester from Harbor Freight and plan to test out my bike but have a few questions. Do I need to have the engine warm to conduct the test or can it be cold? How much difference in the reading would I see between a cold and warm test? Does the piston have to be at TDC, or do I just have to make sure the valves are closed (piston near TCD)? Is there a way, or do I need to lock the piston at TDC to prevent it from moving during the test? At what psi do you normally run the test? Thanks Guys!