The clymers says you have to drain the oil before doing so. The honda service manual doesnt say anything about it. I would rather wait until after the new pump is on, and after "bleeding" the coolant to change the oil. so my question is, is it necessary to drain oil before taking old waterpump off?

Thanks

 

if the bike is on the side stand, some oil might come out of the case when you pull the pump....if you have a rear/swingarm stand making the bike level, you should be fine.