Its probably just the crankcase gasket gone , probably due to overheating ,
its easy to do with the correct tools ie torque wrench, haynes manual , and some gasket compound ,
engine has to come off though
if its just the pump your gonna change and youve already got the engine off the bike , you could do it in about 2 hours
if i wer you id also check the thermostat as if it sticks your gonna overheat as in the thermostat keeps the water in the engine untill hot enough for it to open and start flowing ,
well like a car works , you could take the thermostat out ,(its on the cylinder head , bike heat up pretty quick anyhow
dna jase, February 2008