1. adjust the fluid level to just above the bottom hole.
2. stand on the left side of the bike and squat down. Grab the front tire with your left hand. Take your right hand and push the brake caliper in with a firm, hard and steady pressure.
This is going to push the caliper piston back into its bore, purging the air bubble out of the line and into the master cylinder.
3. Now fill the master cylinder to within 1mm of the top.
4. pump the lever until the brake pads are fully seated on the disc.
5. Notice the fluid level is low again. Top off the brake fluid and install the cover.
You should now have a firm lever and good brake action.