The flyscreen, or windshield, on your Vespa scooter provides additional wind protection, which can be beneficial on long rides at higher speeds. You only need a few basic tools to install the flyscreen.
Unpack all the parts that accompany the new flyscreen and its mounting brackets. Count the parts to make sure you are not missing any hardware. Compare against the included instructions and inventory list if one is provided.
Set up each securing bolt ahead of time by matching it with a washer and lockwasher (this is the hardware securing the brackets to the scooter headset). Attach the brackets to the flyscreen carefully and hand-tighten only.
Take the brackets and connected flyscreen and attach them to the scooter headset, lining up the brackets to the screw cavities underneath the headset frame. Hand-tighten the screws with washers to hold the assembly in place. Make sure to fit the screen over the headset and headlight so it's not blocked. You may need to tap the bolts into the headset depending on your windscreen hardware.
Use a socket wrench and appropriate socket size to tighten the headset securing bolts. Tighten with the wrench until you feel solid resistance. Do not over-tighten.
Adjust the windshield/flyscreen position while it's still loosely attached to the brackets. Sit on the scooter if necessary to determine the right height for the screen. Make sure it does not lean back and touch your helmet while riding. Use a socket wrench and crescent wrench to tighten the brackets to keep the screen in place.
If a headset screw does not screw in smoothly into the headset, don't force it. Over-tightening or forcing a bolt into the headset will cause the threads to strip. The headset is made of aluminium, a much softer metal than steel.