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I've heard lots of suggestions on how to fix this issue but the best result I have had follows .....
1) Remove front caliper & pads, pump out the pistons as far as you dare before they pop out of the caliper ( I think better to only go 3/4 of the way than have them come all the way out ;-) ). With some spray-cleaner (brake or carb cleaner, or engine start spray) & toothbrush, clean the the pistons so they are clean & smooth.
2) Deglaze the brake pads, just rub them on a concrete floor until any shiny patches are gone.
3) Get some course emery/sand paper and deglaze both sides of the disc brake as much as possible. Then wipe-down with spray-cleaner & clean rag .
4) NOW the main point that transforms the brake; smear some 'red rubber grease' (I bought a small tube from the local auto parts store) around the caliper pistons before you push them back in, you may need a small flat-blade screwdriver to get the grease all around the pistons. Remember to push both pistons in at the same time, as they are almost all the way out, to push on one only would make the other piston pop out, then you've got to clean-up the mess and re-oil & bleed (headache). Once you've pushed the pistons home, wipe off the excess grease left around the rim of the pistons,
Using this method has given me the best results by far, it cut-down the free-spinning drag by more than half, try it and let us know your thoughts.
Melbourne, Australia. Current rides: '11 RMZ450, '84 CR500, '06 DRZ400, '79 KX250 with 400 engine, '06 GSXR1000 full Yosh racebike.
