The way I always cleaned the hard to find NOS windshields on my FLT Harley as well as the face shield on my helmet was to use the blue paper shop towels ( available in USA, a very heavy paper towel
meant to be used as a shop towel, several layers of soft paper towel would also work ). Soak the paper towels and apply to the windshield. Reapply as necessary until bug bodies have absorbed enough
water to soften. Then wipe off most of bug goo with the saturated paper towels (soft cloth like T-Shirts would work too). Finish cleaning with Novus #1 plastic cleaner, a product made for cleaning plastic aircraft
windows. Novus also comes in #2 and #3 for polishing out scratches but the point is to soften the bugs so you only need #1 to finish cleaning and avoid using the heavier polishes. The polycarbonate plastic
used for DOT approved windshields in the USA has a coating on both sides. Once you damage this coating by excessive cleaning/polishing or using harsh chemicals meant for glass, the windshield quickly deteriorates and requires replacement. Novus is available at general aviation aircraft supply stores and at some Harley and other motorcycle dealers.
