Water pump seal??

[nick790]

I started my EC 250 08' after a top end rebuild last night, topped the water up with coolant while it wa idling, topped it up a bit more, and some more, then notiched it all coming out the power valve breather . Took the power valve cover off to see a steady streem of water coming up the power valve push rod hole .
Am I right in thinking the water pump seal has gone, or could it be something else? Is it an easy job? Does the whole side cover have to come off? What parts to I need and how much?

I've only ridden the bike for an hour, and since then I've had to rebuild the top end and have the barrel replated, suppose to be racing today and now this, I'm starting to loose my patience.

Please help me restore my faith in the Gasser, many thanks in advance.