Motorcycle The 2003 Big Dog Mastiff is a factory-built custom pro-street chopper featuring a powerful 107 cubic-inch S&S V-twin engine and a rigid-looking softail frame. 6-speed Baker drive system delivering power smoothly to the wide rear tire, Air-cooled 107 cubic-inch (1,750cc) S&S V-twin paired with an S&S Motorcycle. Equipped with a wide rear tire (such as a 240-series) and a large front wheel, giving it an unmistakable presence