Because there are no windshield vents made specifically for the GL1100, I went to Cyclemax to find one that might fit. They had two different vents, one for the GL1500 and one for the GL1800, and they let me try both to see which would better fit the curve of my GL1100's windshield. The curve on the GL1500 vent was too sharp, but the GL1800 windshield vent fit perfectly, so I purchased this GL1800 windshield vent.
1. When I got the vent home, I took it out of the package. It is a two-piece item, held together with two hex screws and nuts and a plastic clip on the bottom, and a plastic lip on the top.

2. The first thing to do is to sit on the bike and hold the vent up to the inside of the windshield to try to get an idea of where you want to position it. This will vary on your seating position, your height, and personal preference.

3. Next, remove the nuts, washers and screws, and carefully seperate the two halves. Make sure not to lose the rubber grommets on the inside piece.

4. The vent comes with a template used for installing the unit.

5. Using scissors, cut out the template just inside the black lines as shown. We want the original cut to be slightly small, as we will enlarge it as the hole is trimmed and smoothed to fit the vent.

6. Using painter's tape, tape the template to the outside of the windshield in the approximate position you want the vent to go. Position the inner half of the vent on the inside of the windshield to verify that the template is positioned properly.

7. Measure the distance from the bottom of the windshield to the bottom of the template opening. In my case it was four inches.

8. Using painter's tape (painter's tape doesn't leave adhesive goo behind like regular masking tape), on the inside of the windshield, tape over the area that will be cut, with a good couple of inches extra on all sides. It's a good idea to make at least two layers of this tape. The tape secures and strengthens the edge of the windshield around the cut, to prevent it from fracturing while being cut and worked.

9. Remove the template, and tape over the same area on the outside of the windshield, again overlapping at least two layers of tape.

10. Put a piece of painter's tape below the windshield, measure between the two screws, and put a mark halfway between them. This is the center of your windshield.

11. Fold the template in half to identify the exact center of the hole that you cut out. Mark the fold.

12. Position the template on the windshield, lining up the center marks on the template with the center mark below the windshield. This ensures the template is centered correctly on the windshield. Measure from the template opening to the windshield trim on both sides, ensuring the measurement is the same on both sides to ensure the template is level. Ensure the paper is flat to the windshield during this process. Once you're satisfied with the template position, tape it in place in all four corners to prevent it from moving.

13. Draw around the inside of the template onto the painter's tape.

14. Remove the template, and you will have your cut line remaining.

15. The cutting and trimming of acrylic is messy and dusty. To reduce the cleanup, tuck an old towel around the dash to catch the plastic dust.

16. Using a fairly large drill bit, drill the four corners of the template. Acrylic is relatively brittle, and when subject to stress, any sharp corners will be stress points and subject to fracture. As a result, we want every corner to be a fairly wide, smooth radius. This is why we drill the corners first with a large drill bit, to put a large radius corner in place instead of the sharp corner that would be produced by a straight cut. This is true for the finished product as well - we never want any sharp corners, everything should be smooth and rounded.

17. The corners should be drilled just inside the lines, as shown.

18. The next step will be made far easier if you have a rotating tool such as this Dremel tool. You can use a hacksaw blade to do the cutting if you don't have a Dremel tool - but why? This is a perfect excuse to go out and buy a new power tool. Take advantage of it! If you are using a hacksaw blade, begin cutting by inserting the blade into your drilled holes.

19. Using a cutting disc in the Dremel tool and two hands on the tool, and with the tool on its highest speed, cut along the lines on the outside of the windshield. Try to keep the cutting disc as perpendicular as possible to the windshield. Note: This process will create lots of plastic bits flying around - eye protection is required!

20. Check on the inside of the windshield to make sure the cuts have made it through all the way. If there are areas where the cut has not made it through to the back side, go back over the cut to make it full-depth.

21. Once the cutting has completed, the piece cut out should just fall out. If it is still held in place with some uncut acrylic, DO NOT attempt to snap it out! You will very likely cause a crack that will travel well outside the area of your cutout area, destroying the windshield. Instead, use your cutting tool to complete the cut. Once complete, remove the cutout piece.

22. The next step is to smooth and trim the cutout area. This can be done quickly and easily with a rotary file in your Dremel tool as shown, or not so quickly with a half-round hand file. Use the flat portion of the hand file to trim the flat areas of the cut, and use the round side of the file to smooth the corners. The round side of the hand file is good for rounding and smoothing the corners of the cut even if you use a rotary file for trimming the remainder of the opening. Remember, no sharp edges should remain - everything must be smooth! Again, unless you like bits of plastic in your eyes, you need eye protection.

23. Continue to smooth and trim the opening, fitting the outer portion of the vent and identifying the areas in the windshield opening that need to be trimmed in order to get it to fit flush. Remember, the original opening was made slightly small, so that the trimming process would create an opening that fit well. The outer portion of the vent fits by hooking the top in place, then pushing the bottom in as shown.

24. Once the opening has been trimmed to fit the vent, use a soft brush on a vacuum cleaner to clean up the plastic dust you have created.

25. Carefully peel off the painters tape from the inside and outside of the opening.

26. Using sandpaper or a fine file, smooth the opening, and round off the edges of the cut. Again, vacuum up any dust.

27. Fit the outer portion of the vent into place.

28. Once the outer portion of the vent is in place, you will see the "L" channel at the top that hooks into the inner portion of the vent. For my installation, the Slipstreamer windshield was about 0.5mm thicker than the standard windshield. As a result, before I installed the front portion of the vent, I used a heat gun on its lowest setting to gently soften the "L" channel, and bend it slightly outward.

29. Hook the top of the inner portion of the vent into the "L" channel of the outer portion of the vent as shown. Once hooked in, push the bottom of the inner portion of the vent into place until the clip locks it into place.

30. Insert the hex screw and washer into the front portion of the vent, through the rubber grommet in the rear portion of the vent, then put the washer and nut in place. put both screws and nuts in place, then gradually tighten both sides, alternating until both are tight. Don't tighten them too much - remember this is only plastic you are dealing with.

31. This is the vent when it is fully installed, shown in the closed position. In the closed position, air can still escape through the small slots on the top of the inner portion of the vent, which is used to defog the inside of the windshield.

32. The vent can be opened to different positions - this is not so much to regulate the amount of air, but to change the direction of the airflow - you can have it hit you anywhere from mid-chest to right in the face.

33. Here is the completed installation. There will be some amount of plastic dust remaining - you can get the vacuum out again, or just go out and blow it off the fun way.

