The Pulsar 150 typically comes with a stock tire size of 2.75-17 for the front and 100/90-17 for the rear. The tire size you mentioned, 120/80-17, is slightly wider than the stock size for the rear tire. While it is possible to fit a wider tire on the Pulsar 150, there are a few factors to consider:
Wheel Clearance: Ensure that there is enough clearance between the tire and various components such as the swingarm, chain, fenders, and other parts of the motorcycle. A wider tire may rub against these components, potentially causing damage or affecting the bike's handling.
Suspension Compatibility: A wider tire can have an impact on the suspension dynamics and geometry of the motorcycle. It may affect the handling characteristics, such as the bike's cornering ability and stability. You should consider consulting with a qualified mechanic or tire specialist to assess the compatibility and potential impacts on the suspension system.
Speedometer Accuracy: Changing the tire size can affect the accuracy of the speedometer and odometer readings. A larger tire circumference can result in lower indicated speeds and inaccurate mileage calculations. Keep this in mind when considering a different tire size.
It's important to note that modifying the tire size from the stock specifications may have implications on the motorcycle's overall performance, handling, and safety. It is recommended to consult with a knowledgeable mechanic or tire specialist who can provide guidance specific to your motorcycle model and advise you on the appropriate tire size modifications, if any, based on your requirements and the compatibility of the bike.