Windshield Trimming Instructions

All National Cycle aftermarket and replacement windscreens are top quality wind protection accessories. Proper care can help these windscreens give many years of motorcycling enjoyment.

Because each rider has their own combination of physical height and/or motorcycle accessories, trimming may become necessary for the best performance. National Cycle polycarbonate windscreens can easily be trimmed if a few simple procedures are followed.

How to Trim Your Windshield

Note: Use of a jig saw or saber saw is NOT recommended!


If the windshield is to be shortened from the top, remember to choose the new height while seated on the motorcycle (both wheels on the ground), with the motorcycle normally loaded. You should be able to see just over the top of the screen, in case the view should become obscured because of rain or dirt.

Note: Too much material should not be removed as this will affect how far the air deflects off the top of the screen. The rake angle of the screen, which is adjustable in some applications, will also affect how the air comes off the screen.


Windshield TrimmingEstablish the vertical centerline on the windshield first, then mark the perimeter line to be cut with a grease pencil or china marker, as these can be easily cleaned off with simple benzine without harming the windshield. A ruler or piece of tracing paper can be used as a guide from the centerline to duplicate one half of the drawn trim line to the other half, ensuring reasonable symmetry.

An effective way to secure a larger windshield is to stand it on the floor and grip it with your knees while seated in a chair. This leaves both hands free for filing or sanding.

Trimming can be done by sanding or filing with a coarse, 60-80 grit file. Since shudders, jolts, and sudden shocks can promote cracking, use a smooth continuous motion. A flat belt sander will remove material quickly, but keep the sander moving back and forth for a smooth edge.

If a large amount of trimming is required, a good quality band saw can be used safely. Protect the screen with masking tape before cutting. The blade should have about ten teeth per inch. A hack saw will also work well, but be careful not to let it bind in the cut.

Once the desired shape is achieved, use a coarse file or sandpaper to round the edges.

Finishing the Trimmed Edge

Use a very soft cloth and a fine grade buffing compound. Jeweler’s rouge or Meguiar’s Mirror Glaze MGH-10 are best for this type of buffing. We recommend hand buffing, but very light pressure with an electric buffer will speed work on final edge finishing.

Keep moving across the windshield edge while buffing, and try not to concentrate on a small area too long.

Carefully clean your windshield and reinstall it on your motorcycle.

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