I have an 05 crf450 that sat for about 3 weeks while the engine was getting rebuilt. Since then, the rear brake has not worked properly. There is plenty of resistance when pushing down but it will not even lock up the rear wheel. So I bled it with my vacuum pump, but no improvement. I bled it manually but still no improvement. So I installed a new rebuild kit for my master cylinder (and bled it again), but still no improvement. My brake pads are next to new and look great. I can see the caliper push the pads against the rotor and plenty of resistance is felt in the lever. It will cause the bike to slow down eventually but it wont lock up the wheel. Any ideas? Ive heard of brake lines possibly swelling?