Did you replace pads or add fliud recently? If you dont see any fluid leaks and the resevoir is full and the brake pad isnt worn down to nothing, then there is likely some air in the lines somewhere. It only takes a small bubble to give you a squishy feel. Bleeding brake lines can be a pain and take some time but it is necessary to do it right, There are Youtube videos that may help.
Had all kinds of grief with my front brakes, 99 chief and I ended up buying the new improved front master cylinder from Mark at indian moto parts.plus I got his best front pads and drained all the old fluid and it made a huge difference. I had decent pressure before I did all that but it just didn't stop like a bike should. Now it does. Also you can't mix dot 3, 4 or 5 together.