The top speed of a Ducati Monster 1200 depends on various factors, such as road conditions, rider weight, and aerodynamics. However, the Ducati Monster 1200 is capable of reaching speeds of around 155 mph (250 km/h) under ideal conditions. It is important to note that riding at high speeds can be dangerous and is best done in controlled environments such as racetracks. Always follow traffic laws and prioritize safety while riding any motorcycle.