One of the problems with the Empulse cooling system is that there is no expansion tank in the system. If you fill to the top of the fill pipe where the pressure cap goes there is no place for excess coolant to expand to when it heats up. I try to leave the coolant level toward the lower end of the hose that is attached to the radiator cap. Its not easy to do that as the hose is black and there is no easy way to see the level. In my case, I put a small hose on the hose barb located by the radiator cap to direct any excess coolant that might come out if it is overfilled. I a perfect world, that hose should be attached to an expansion tank (like almost every other cooling system in existence) but there is no real room for one on the motorcycle. I think that it is important to keep some air space in the system to limit the pressure in the system. With no air space for the hot coolant to expand into pressure spikes will occur in the system on a regular basis. The normal coolant temperatures in the Empluse don't even require a pressure cap to keep the fluid from boiling. I haven't looked at the cap, but a very low pressure cap should be used. It's possible cooling system excess pressure is causing some of the motor coolant leaks we are seeing.
