To accurately determine the distance a 150cc motorcycle can cover using 1 liter of petrol, we need to consider several factors. Unfortunately, the information you provided about turning off the engine at a specific speed is not sufficient to calculate the fuel efficiency.
Fuel efficiency depends on various factors such as the specific model of the motorcycle, road conditions, driving style, and other variables. Additionally, turning off the engine while riding at a speed of 60 miles per hour is not a practical or safe approach. Motorcycles are designed to be operated with the engine running continuously.
To estimate the fuel efficiency of a motorcycle, it is more common to refer to a standardized test called the "fuel consumption rate." This test measures the amount of fuel consumed by the motorcycle per unit distance traveled. The results are typically provided in terms of liters per 100 kilometers (L/100 km) or miles per gallon (MPG).
If you can provide the specific make and model of the motorcycle you are referring to, I can try to provide you with some general information about its fuel efficiency.