How to Cut Down Motorcycle
Windshields for Safety
Rain, dirt, bugs, fog, and
distortion can make your motorcycle's windshield a dangerous optical barrier
between you and the road. Here is how to safely and neatly cut it down so you
can see over it. Story and photos by John Bingham.
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Cutting a
motorcycle's windshield for height is more than just a matter of comfort and
style, it's essential to good visibility. Being able to see clearly is
fundamental to the safe enjoyment of motorcycling. And, getting your bike to
fit you just right is a rewarding part of the whole motorcycling experience.
There
are generally two schools of thought on what constitutes "the right
height." You're either a rider who wants to be comfortably ensconced
behind a large enveloping view port, or one who appreciates the protection of a
windshield but feels most comfortable being able to see over it. (The Motorcycle
Cruiser staff falls entirely into the latter camp. We have even been known
to cut down an annoying windshield out on the road, as we did with the Yamaha
Royal Star Venture's shield on our
ride to Alaska.)
Certain
weather conditions make looking through a windshield more than a little dicey.
Fog and mist can cling to a windshield, blocking essential forward vision and
increasing annoying glare at night. My own beef is the triple whammy of riding
in the rain in traffic at night. Road spray produced by other vehicles seems to
be especially adhesive. And it sticks not just to the front of the windshield
but also to the back, so you have two layers of droplets to try to see
through.
In heavy
traffic, road speeds are not conducive to the natural sheeting effect of water
from windblast; the result is impaired visibility when vision is of the utmost
importance. When you combine the water on the windshield with water on your
face shield or goggles the situation only gets worse.
It's Easy
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So, how
do you go about cutting a windshield to fit you? It's actually quite simple and
can usually be done without removing the windshield from the bike. It's easily
accomplished in a small amount of time -- an hour or so -- with tools many
do-it-yourselfers already have. As with any modification you make to a
motorcycle you should proceed with caution. Since a windshield is an integral
part of a motorcycle's aerodynamic package, you may make changes that could
influence overall performance. Keep this in mind any time you're making
modifications to original equipment or when installing and modifying
accessories.
How Much is Enough?
In this
case, less is more. There's no need to remove too much material on the first
cut. It's easier to try a smaller amount and test it out. Then, if needed, cut
some more. Generally, you should be able to see over the upper edge of the
shield when seated comfortably. Since there are no hard-and-fast rules, you can
try one of the following methods as a guide to determine just how high you want
the shield to be.
Immediate
path of travel method: Being able to see the roadway in your immediate path
of travel means seeing two to four seconds ahead. At 30 mph that translates to
88–176 feet. You can pace this out on the street; pinpoint accuracy is not
essential here. We're simply trying to find a comfortable position.
Headlight
aiming method: This method can probably be done in your driveway. Find a point that is
the same height as the center of your motorcycle's headlight, 25 feet ahead.
You can make a mark with tape on any wall and measure out where the motorcycle
should be positioned. Where the front tire touches the pavement is a good
reference point for your measurement.
Marking
method:
While riding, note approximately where you are looking through the windshield.
Place a piece of tape or draw a line with a grease pencil just below that. The
next time you ride, determine whether you are looking comfortably above that
line.
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Once
you've selected a method, sit on the motorcycle in as comfortable a position as
possible and carefully mark the new upper edge with something nonpermanent such
as a crayon, grease pencil or a piece of masking tape. You're now almost ready
for surgery, but we still have to figure out the right shape.
Be the Designer
Unless
you have something extraordinary in mind (in which case you're on your own)
copying the original shape or curvature of the existing windshield is probably
the best way to go. You can do this by making a pattern. To copy the existing
shape, place the card stock or art board behind the windshield and carefully
trace the upper edge. Cut the card along the line you have traced, and you've
got your pattern.
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Marking the
Windshield
You
could just mark the plastic to make your cut, but you'll need to protect it from
the inevitable scratches the tools will make. Masking the area that will be cut
provides the protection you'll need and an ideal surface to mark the cut line.
Mask a large enough area to cover where the new cut will be plus a little
beyond, this will keep the jigsaw base from scratching the plastic. Avoid using
something like duct tape because some tapes use solvent-based glues that could
damage the surface of the plastic. Mask both the front and the back of the
shield.
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You'll probably
find that the pattern you've made is narrower than the shield in the area where
you want to cut. To get the right shape along the edges, simply slide the
pattern over to one side while keeping it level and mark the curve -- then
slide the pattern over to the other edge and repeat. There should be plenty of
overlap in the center to complete the top edge. When you're happy with the line
you've marked, you're ready for surgery. If not, retape and mark again.
No Looking Back!
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You have
reached the point of no return -- it's time to make the cut. The usual
advisories about using power tools apply here. Start with the manufacturer's
instructions, they usually include valuable information beyond the legalese.
Eye protection is a must, and try to come out of this with your fingers intact!
The
instructions will also provide helpful hints about the type of blade to use
and, if your saw has variable speeds, the right choice for plastic. Now's the
time to drape the sheet over your motorcycle; it will make clean-up a breeze.
Begin making your cut at one edge. Right-handed people will find it easier to
cut from right to left. Make a smooth cut by applying steady pressure but don't
try to go too fast. You're trying to cut the plastic, not burn through it.
Care at
this stage will reduce the amount of work necessary to finish the edge later.
Keep the saw base flat against the taped surface and hold the plastic with your
free hand to minimize vibration.
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File the Edge
When
your cut is complete, it's time to finish the edge. Resist the urge to remove the
tape at this stage because it will continue to help prevent scratches from
misplaced filing and sanding. The first stage of finishing the shield's new top
edge is to remove any saw marks and smooth out undulations in the cut. You can
do this using the flat file and making long strokes along the edge. When you
are satisfied that your newly cut edge is smooth, round it slightly. Use the
existing edge from the section that you've cut from the windshield as a guide
for the shape. After the filing is complete it's time for sanding and
polishing.
Sand and Polish the
Edge
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A block
sander is ideal for this next step because it's easy to handle and change
sanding papers. Begin with a coarse or medium paper. A general-purpose or wood
sanding paper is all you'll need. As the edge gets smoother, switch to finer
grades of paper until you've polished the edge to a finish that is similar in
smoothness to the original. You should be able to reach this level of
smoothness with extra-fine grade or 220-grit paper. Again, use the original
part as a guide for shape and final finish. Wipe the edge clean and use a
plastic cleaner/polish to complete the job.
Sure you
can use power sanders for finishing the edge. But remember, these tools were made
to remove materials easier and faster. They can help you make mistakes more
quickly too!
Remove
the sheet and dust from the motorcycle, and you're ready for a post-operative
test ride.
Cutting
a windshield is a relatively easy modification that can help you see properly
in all conditions. In the end you will have the satisfaction of customizing a
bike to your personal specifications while making it safer, too.
The author is a
long-time motorcyclist with a background in motorcycle safety education.
For more articles on
how to customize, maintain and modify your motorcycle, see the Tech & Custom
section of MotorcycleCruiser.com.