Handling
A narrower tire will have less contact with the road, which can make the motorcycle more unstable and difficult to handle. This is especially important when cornering, as a narrower tire is more likely to lose traction and cause the motorcycle to slide.
Braking
A narrower tire will have less braking power than a wider tire. This is because a wider tire has more surface area in contact with the road, which allows it to generate more friction and slow the motorcycle down more effectively.
Stability
A narrower tire is less stable than a wider tire. This is because a wider tire has a larger footprint, which helps to keep the motorcycle from tipping over. A narrower tire is more likely to roll over, especially when cornering.
For all of these reasons, it is generally not a good idea to put a narrower tire on the front of a motorcycle. If you are considering doing this, you should weigh the risks and benefits carefully and make sure that you are confident in your ability to handle the bike safely.