I haven't heard of soaking them for 24 hrs , but I do let them soak for a minute or two so they arent dry when you install them. As CBX stated, Factory Kawasaki clutches seem to hold the best so thats what I'd run in all of my KX's.
And listen to Cam, you dont have to crank the H*LL out of the clutch spring bolts. Torque them and it will save a lot of headaches later.