South West Bikers | Motorcycle Forum

Keeping the lever under pressure for an amount of time doesn't make the air bubbles go away, it just compresses them, and then after the lever is released they'll expand again to their previous volume and nothing will have changed. Get a decent sized syringe and feed fluid in through the bleed nipple via a tube, closing the nipple when you've stopped pushing, and periodically removing fluid from the reservoir before it overflows. The problem is simply air bubbles stuck in the calliper that aren't releasing. Take the calliper off, try tapping with a soft mallet, orient it in different directions whilst tapping to free the bubbles, then refit and try bleeding as described.
Next time you clean the callipers, don't touch the sodding brake lever!

Worse case senario, remove caliper, disconnect brake line, open nipple and pour fluid directly into caliper until it flows cleanly out of the nipple, nip up nipple, reconnect brake line but dont fully do up banjo, pour fluid down the line until it pisses out of banjo, tighten banjo and do final bleed as normal, there should be very little air in the system but also the pockets behind the pistons will be full of fluid without any air lock. Take you an hour or so, but will definately solve the problem.

Oh yeah and i agree with Scotty on the lever trick, its a bit of an old trick that doesn't really work that well and also if your seals aren't in the best of condition the constant pressure overnight can force fluid past the seals. Not a good thing.