By the sounds of it, you will not have the pipes back on the bike any time soon?
So you want to get rid of the water to prevent it from causing any rust I guess.

Here are some obvious/stupid suggestions:

1) Put the pipes on another bike and go for a ride
2) Get some heatproof tape and connect up a heat gun/paint stripper for a few hours
3) Put the pipes in a hot water cupboard for a month
4) Hang them in a chimney above a fireplace/furnace
5) Connect them up to the exhaust of your car and go for a drive.
6) Next time your girlfriend goes sunbathing, ask her to take the 2 pipes with her.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...