ATK 1991 two-stroke catalog, 406MX (recorded): TMX 38 mm Mikuni, 2.4 gal (9.0 L), 213 lb dry. 406 Cross Country: 3.7 gal (13.9 L), 218 lb. Dirt Bike (Nov 1990, quoted): 'around 10hp more than the stock Rotax 406 motor'.