Flying Horse 2-Stroke Motorized Bicycle Engine Chrome Muffler &ndash; Gas Bike Muffler Replacement (Black) The Black Muffler will fit most 2-stroke 48cc and 66/80cc bicycle engines to safely expel exhaust the engine will produce Installation is simple: unbolt your stock muffler from your cylinder, replace the muffler gasket (if needed), fit the new muffler up to your cylinder, install, and you're ready to ride Gloss Black finish; 30mm Stud Spacing