bleeding the rear, very slow

Some feedback please. I was bleeding the rear caliper tonight on my 07rsv1000r and it was taking forever. I did everything the proper way (removed caliper and lifted high etc..) but it just took so long before the level in the master cylinder reservoir even started to go down. I remember reading keep topping reservoir up because it will drop quickly while bleeding. I pumped the brake and loosened off the nipple atleast 20 times before having to refill it. is this normal. I saw a few initial bubbles but after that i never saw a real thrust of fluid enter the jar. I havent ridden bike yet just tested rear pushing bike in garage. it works better than before but not great. I'm wondering if someone can tell me if when opening the bleeder nipple if 1/4-1/2turn is o.k. I tried more but didn't see any improvement. After bleeding for 10 minutes (30 reps) I only emptied the reservoir 1 1/2 times. I'm wondering if there is something wrong with the mastercylinder. maybe its not working properly?

I'm used to bleeding the brakes on cars and have never had an issue like this, typically as soon as you loosen the bleeder nipple while holding downward pressure on the pedal the fluid rushes out. then i close the bleeder screw and release the pedal. fluid goes down in reservoir. repeat untill flushed through and clear. Why isn't it happening like this on my bike?

Thanks for all the advice! I dont know any of you and am amazed at how quickly strangers offer help. much appreciated!!! I'm gonna hang a 4l jug of oil on the rear brake lever tonight and re-bleed it again tomorrow. So this syringe method? If I use a turkey baster and try to suck fluid out of the open bleeder nipple that may do the trick. I'll give it a try! I'll also try pumping the lever between bleeds, maybe this will help to build pressure for a more intense bleed.
I had the bike bleed at the dealer around 4000kms ago and worked amazing, very touchy for the 1st 500kms. afterwards its been all downhill to the point where i can stand on it and nothing would happen. I can only make it work when up on rear stand!
Is bleeding the rear regularily the only real fix? I cant believe it, aprilia says 20minute job. its easy enough job but is more like 1.5hrs.

Thanks for the tip! So a syringe (like a medical one?) I've never reverse bleed before but from what i gather unscrew reservoir cap, place syringe tight to bleeder nipple and unscrew bleeder 1/2 turn and pump the syringe to force fluid into the caliper thus putting pressure towards the master cylinder. Do i hold the mastercylinder lever down while doing this? Does it matter if i leave the caliper fitted to the bike while bleeding this reverse way? Any bits of advice on a step by step would be greatly appreciated!

Just thought I'd give an update. I hung a 4l washer fluid bottle on the rear brake overnight and most of the day. Problem appears fixed for now. I am able to lock up the rear quite easily now with moderate pressure. Went for a good 20minute run and used the rear hard everytime making sure it would work. Perfect. Next time it acts up I'm gonna try the syringe method as it sounds like it will ensure no air is left behind! Thanks again for all the tips!