Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 90, § 7U

No person shall operate a motorcycle intended for use on the highways of the commonwealth and registered under the provisions of section two of chapter ninety at any time or under any condition of grade, load, acceleration or deceleration in such a manner as to exceed eighty-two decibels when operated within a speed zone of forty-five miles per hour or less, or in such a manner as to exceed eighty-six decibels when operated within a speed zone of over forty-five miles per hour measured at fifty feet using the prescribed highway vehicle sound level measurement procedure.

No person shall operate a motorcycle intended for use off the highways of the commonwealth and registered under the provisions of section twenty-two of chapter ninety B at any time that exceeds one hundred and three decibels measured at twenty inches, or one-half meter, using the prescribed stationary vehicle sound level measurement procedure.  For enforcement purposes a tolerance of plus two decibels shall be applied to all measured sound levels of in-use vehicles to provide for variances in equipment calibration, measurement site characteristics and measurement techniques.