Should the water pump move water just from kicking

Posted this in a Vintage section of another forum and got no reponse so I am trying here. Question should apply to modern bikes also.

83 YZ 125 Overheating. Everything checks out OK visually. Water pump seal looks good. Oil and radiator fluid clear. Pump turns when kicking over the motor and no broken blades on pump.

I removed one hose from the water pump. Shot water with my garden hose into hose and it went through the radiators and engine and came back out where I removed the hose. So, I assume that there are no restrictions. Another test I performed was to put two hoses on the inlet and outlet from the water pump. I then poured water in one side until it came out of the other hose. Since the hoses are about 10 inches higher than the water pump, there is water in both hoses and in the pump. I then kicked the bike over and though that water would come out one side but it didn't change at all.

Does anyone know if water should have moved through just be kicking or does the pump have to be moved faster (ie. bike running) to get the water to flow?

Bad Radiator Cap

The radiator cap may definitely have been the issue. Problem is that it overheated during a race and had a slight seizure. So, I can't start it to see if the pump is OK. I was checking the water pump and flow to make sure everything is correct before I put a new top end on it. I think I will end up putting the new top end on, replacing the water cap and then monitoring very closely.

Thanks
flphil