Muffler construction for motorcycles

Claim 1

IN A MUFFLER CONSTRUCTION FOR THE INTERNAL COMBUSTION ENGINE OF A VEHICLE SUCH AS A MOTORCYCLE, EXHAUST PIPE MEANS, SOUND MUFFLING MEANS IN SAID EXHAUST PIPE MEANS, AND MEANS MOUNTING SAID SOUND MUFFLING MEANS FOR MOVEMENT FROM A SOUND MUFFLING POSITION TO AN UNOBSTRUCTED, NON-MUFFLING POSITION, SAID SOUND MUFFLING MEANS COMPRISING A BUTTERFLY MEMBER, SAID BUTTERFLY MEMBER INCLUDING A RING SHAPED PORTION DISPOSED IN A PORTION OF THE EXHAUST PIPE MEANS WHICH IS OF CIRCULAR CROSS SECTION, SAID MOUNTING MEANS MOUNTING SAID BUTTERFLY MEMBER FOR MOVEMENT FROM A POSITION WHERE SAID RING SHAPED PORTION IS IN CONCENTRIC RELATION TO THE EXHAUST PIPE MEANS, TO A POSITION WHERE THE PLANE OF THE RING SHAPED PORTION IS PARALLEL TO THE AXIS OF SAID EXHAUST PIPE MEANS, SAID RING SHAPED PORTION HAVING AN OUTER DIAMETER LESS THAN THE INTERNAL DIAMETER OF SAID EXHAUST PIPE PORTION BY AN AMOUNT SUCH THAT THE ANNULAR AREA BETWEEN THE RING SHAPED PORTION AND SAID PIPE MEANS PORTION WHEN SUCH PORTIONS ARE IN CONCENTRIC RELATION, IS AT LEAST ONE-HALF THE AREA OF THE OPENING OF THE RING SHAPED MEMBER.