First get a replacement bolt, filter, orings, and a good quality 6 point 12mm socket).
Optional, get some carpet or cardboard to lay bike on left side so you can hammer the socket onto the remains of the hexhead, try to get into a good spot before you start to hammer the socket onto filter bolt. If its too loose try next size smaller socket, size not important can be inch or mm, hammer it on then try to loosen. If that wont get it done the next step is to use a chisel at an angle that will loosen the bolt. If you drain the float bows and remove the fuel tank, maybe drain the engine oil (you're doing an oil & filter right?), that helps to see what youre doing and use the hammer more effectively with the bike on its side on the floor. Oil is going to start to leaking out when you get a half turn or so loosened, you may want to stand up the bike to get drain pan in place before oil starts to drain. When you install new bolt and Orings don't over tighten and use a 6 point socket. Take your time, it can be done, I've done a dozen or more, using a 2 pound "Drilling Hammer", (short handle) and a chisel that not sharpened to cut but has a flat edge not intended to cut but to push.. Pay attention to which direction you are turning the bolt, sometimes people get confused and turn the wrong direction when its upside down. Good Luck. HondaJohn.
A forum community dedicated to Honda Twin cylinder motorcycle owners and enthusiasts. Come join the discussion about performance, engine builds, classifieds, modifications, troubleshooting, maintenance, and more!