So have you done a bleed of the brake system? Keep in mind the in coming fluid hose is on a banjo bolt (where the brake hose connects to the caliper) that has the bleed nipple is all the same fitting, so no fluid flushes the area behind the caliper puck. It can short circuit right out the bleed nipple. It is not a straight forward bleed job.
Cover your gas tank with some cloth to keep any drips of brake fluid from that great orange paint. Lift the brake reservoir cap and remove old fluid via a suction device. Clean the cap. Go down to one caliper and remove it. Push back the pads and wedge them open. remove the fluid pushed back into the brake reservoir. Now put in fresh DOT 4 fluid and bleed that caliper by opening the bleed nipple at the same time you slowly squeeze the lever, now close the bleed nipple before releasing the lever so you do not suck in any air. Keep doing this until you see clean fluid. Maybe 10 or 15 times. now leave it as is with pucks wedged back and do the other side. Now put the calipers back on the bike. Now bleed just the same, squeeze the lever when opening the bleed nipple then close the nipple before releasing the lever. Keeping an eye on fluid level in the reservoir. If it gets to low and sucks in air you have to do it all over again. After one side is done do the other. Now you should feel the lever firming up. Wedging the pads back either use wood or as I have a pair of brake pad push back tools because Ii do lots of bikes. See some YouTube stuff on this, get some ideas of procedure. The idea is to force out any air in the system.
Zero air is only end point. It is a good idea to clean the edges of the caliper pucks that push on the brake pads before you push them back past the seals in the caliper. Some spray brake cleaner is okay but isopropyl alcohol is best with a small brush and make sure it has evaporated before pushing back the pistons. I say to cover the gas tank with a cloth because when you release the brake lever it tends to spit out fluid from the reservoir. I keep a spritz bottle of water and a bit of dish soap on hand so if any fluid gets on the bike anywhere I can spray it and wipe up. There is more to this but then I go down the anal trip of how I do the job.
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