Flying Horse 48cc/49cc/66cc/80cc 4-Stroke and 2-Stroke Motorized Bicycle Exhaust Gasket &ndash; Gas Bike Muffler Gasket The Muffler Gasket works for most 2-stroke bicycle engine kits, whether you're running a 48cc or a 66/80cc engine kit To install simply remove your muffler, take off the previous gasket, replace with this gasket, and re-install the muffler 30mm stud spacing, typical of most bicycle engine kits and standard mufflers