My bike has started spitting coolant around the rim of the radiator cap. I bought a new cap and made sure the line to the overflow reservoir flows properly. That seemed to help some but not completely. I do see coolant move from radiator to reservoir and back as she heats up and cools down. It still spits at me when I run at sustained mid-to-high revs. I am riding in 90 degree weather during the summer. I'm suspecting a compression leak in head gasket. Does anyone have any other ideas? How do I confirm the diagnosis before tearing into the engine?