Installing a Kisan Pathblazer Headlight Modulator
Mounting a motorcycle headlight modulator is an easy procedure that will help increase
the visibility of your motorcycle to oncoming traffic. Motorcycle headlight modulators rapidly
flash the motorcycle’s headlight at 240 (plus or minus 40) cycles per minute,
which attracts the attention of oncoming drivers. Headlight modulators for
completely legal in all 50 states 1.
modulators are now legal in Canada; see the wBW technical article page
describing the Canadian regulations in
Motorcycle headlight modulators are designed to increase the visibility of the
motorcycle in the most critical area, the left front, to help grab the attention
of oncoming traffic. The Hurt study 2 found that "the
failure of motorists to detect and recognize motorcycles in traffic is the
predominating cause of motorcycle accidents".
The study also found that:
Intersections are the most likely place for accidents;
That the view of the motorcycle in the accident is limited;
That conspicuity of the motorcycle is a critical factor, and accident
involvement is significantly reduced by the use of motorcycle headlamps
(on in daylight) and the wearing of high visibility yellow, orange or
bright red jackets; that conspicuity of the motorcycle is most critical
for the frontal surfaces of the motorcycle and rider
Headlight modulators are designed to help address these critical factors.
See note below for an alternate installation procedure if your
motorcycle has a plastic chromed headlight bucket.
Types of Modulators
Headlight modulators are made by several manufacturers. Some modulate the low
beam, some modulate the high beam. Some models let you choose which beam to
modulate. The federal law cited above has other specifications and limitations
on how they work. For example, all modulators must have an automatic system that
stops the modulation at night, but still allows the headlight to function
normally. Fortunately, you don’t have to worry about how it works, as the
modern miracle of microelectronics comes through again and makes it happen!
After careful study (see the abbreviated listing of web sites of modulator
manufacturers below), I chose the Kisan P-115W-S modulator for my 1994 K75
. The reason I chose this model is that the standard K75 leaves very little room
within the headlight cowling behind the H4 headlight to mount any other type of
modulator. Most, if not all, modulators plug in to the motorcycle’s headlight
in place of the 3-prong plug. Some modulators need room for a small circuit
board assembly somewhere near the headlight, and some are large units made for
bikes with a lot of room behind the headlight.
The Kisan P-115W-S is an
extremely small unit, measuring only 40 mm wide and 15 mm thick. It plugs
directly into the headlight, and it has a separate 3-prong plug attached to a
wire cable about 2 inches long that comes off the side of the unit to insert the
original headlight wiring from the bike itself. This gives enough room inside
the headlight cowling for everything necessary. I had no problem at all in
fitting the P-115W-S to the standard K75.
#2 Phillips head screwdriver;
Hammer, preferably a ball peen machinist’s hammer; ¼" diameter round metal file;
Emery cloth, approximately 100 grit; Couple drops of oil, 30 weight or motor oil will do;
Electric or battery powered hand drill; Drill bits: 1/8", ¼", 5/16", and 25/64" (or 10mm);
Center punch; Two six inch or twelve inch scales (rulers); Safety glasses or goggles;
Optional: black silicone sealant.
Note the small size of the Kisan P115W-S modulator (arrow), and
the separate 3-prong plug (attached to red shrink wrap).
Another reason why I chose the Kisan is that it modulates the
high beam. The high beam has a wider pattern than the low beam, and the high
beam throws more light to the left than the low beam.
This maximizes the effect
of the modulated headlight to oncoming traffic, which in the U.S. is on the left
side of the motorcycle. In order to be polite, you can switch to low beam when
you’re stopped in back of a car at a stoplight, so that the flashing high beam
isn’t too annoying to other drivers.
Installing the Modulator
The headlight on the K75 is held on, believe it or not, by one Phillips head
screw on the bottom of the chrome bezel that surrounds the headlight. Loosen the
screw until the bezel is loose. The screw will not come all the way out, but be
careful that the headlight itself doesn’t come tumbling out of the cowling.
After the screw is loose, you should be able to gently remove the headlight from
Carefully pull off the 3-prong plug from the back of the headlight. You may
have to rock it back and forth a bit, or even pry it out using a flat-bladed
screwdriver, but be careful not to bend or break one of the studs. They are
meant to be tight in order to ensure contact without vibrating off.
another little light bulb (the parking light) and a ground terminal (brown wire)
on the headlight. Gently pull the small light bulb out, and carefully pull the
brown ground spade connector off the terminal also and set the complete
headlight assembly aside. You may want to cover the headlight with something so
that no dirt gets into the hole where the parking lamp was. Wrap the cable and
plugs that come from the bike inside the headlight shell in a towel or plastic
bag to protect them during the next step.
Now comes the scary part. In order to comply with regulations to prevent
modulating at night, every modulator must have a device that prevents it from
modulating when it gets dark, while still allowing the headlight to operate
normally. The Kisan modulator assembly has a light sensor attached to about an
18" long wire.
This sensor must be mounted through the headlight cowling
and pointing up. To do this, you must drill a 10mm (or 25/64") hole in the
top of the cowling! Don’t worry, it’s easier than you think! You need to get
over the mental block of drilling into your precious baby, but I justified it by
thinking if I messed up, I would simply plug the hole with a black rubber flush
mount plug, and no one would notice.
Drilling holes in thin walled sheet metal is a bit tricky, as the drill has a
tendency to grab the metal and stall. As an ex-machinist, I know there is a way
to sharpen a drill to help prevent this from happening, but it’s really not
necessary for what you need to do. To help things along, you’ll drill a series
of pilot holes leading up to the big kahuna, the 25/64 incher. Do not try
to drill a large hole in sheet metal without first drilling a series of pilot
holes!! Use a very small drill and work your way up. Be patient!
The hole for the sensor should be dead center on top (12 o’clock position
when standing in front of the bike looking at the headlight) of the headlight
cowling. The sensor must be located in a way that will prevent oncoming
headlights at night from allowing it to activate the modulator, so the best way
to mount it is pointing straight up at the sky on top of the headlight cowling.
You’ll need to locate the hole fore-and-aft along the centerline of the bike,
and side-to-side (or port-to-starboard!) in the middle of the top of the
To locate the position for the hole, I measured back 35 mm from the front
edge of the headlight cowling, which locates the hole about in the middle of the
space from the front of the headlight to the beginning of the instrument module.
Finding the exact center side-to-side is a bit trickier. You can eyeball it and
get pretty close, or I found that you can locate the center by using your two
scales. Use one scale to measure up from the Allen headed screw on one side of
the cowling (they are located at the 3 o’clock and 9 o’clock positions) and
then over to find the center. Repeat this from the other side until you find the
spot where the distance is the same. This should be the center. It turned out
that on my bike the center was located 115 mm from each screw.
Now you’re ready to start drilling. First, put on your safety glasses or
goggles. You must wear eye protection to do this. To start the hole, you must
use a center punch to create an indentation to help locate the drill bit,
otherwise you will not be able to get the drill to start without wandering.
use too much force, as the headlight cowling is just thin aluminum and you may
put a bigger dent than you bargained for. Don’t ask me why I know this! If
this does happen, you can gently tap the headlight cowling from inside to
straighten it out a bit.
You can’t simply drill a 25/64" hole first thing. You must drill a
pilot hole first to guide the bigger diameter drill. I drilled a series of holes
using progressively bigger diameter drills. Start with the 1/8" bit. After
you have that hole drilled, put a drop or two of oil around the hole to help
lubricate the next. Drill the ¼" hole, then the 5/16", then the drill
the final hole using the 25/64". This one may want to grab the edges of the
hole, so be careful. If it gets jammed, simply reverse the drill and let it back
itself out. You may find that if you start the drill before touching the metal
it may go smoother.
After drilling, the hole will have a burr. You must remove the burr using the
round file and the emery cloth.
Now the hard part is over. Here’s where my experiences in installing the
modulator hopefully can help you prevent the mistake I made. The instructions
that come with the Kisan modulator are not very clear on how to actually mount
the sensor in the hole. I even called Kisan to ask about this, and they were
very helpful, but I realized later that I still didn’t understand the
The Kisan modulator comes with a small black grommet to mount the sensor in
the hole. The grommet slides around the cable that holds the sensor, then fits
up tight against the sensor head itself and pops into the drilled hole. The
grommet is designed to keep the sensor tight and waterproof.
Here’s how to do
it right: first pull the sensor itself up through the hole. THEN put the grommet
around the sensor cable (it has a vertical slit to allow you to do this). Locate
the grommet up around the threaded part of the sensor, and then push the sensor
and the grommet unit down into the hole. This may seem obvious, but it
wasn’t to me, and the directions weren’t clear to me either.
should snap in and it will be a pretty tight fit. I had to file my hole a bit to
get it to fit, and I over did it, so the fit was a tiny bit loose. I put a dab
of black silicone sealant around the inside of the hole to make sure it stays
waterproof. You may want to do this anyway, just as extra insurance against
Now we’re getting close. Plug the Kisan modulator into the back of the
headlight. Caution: only push the modulator on until it stops, don’t try to
force it any more after that! Replace the small light bulb and the ground
terminal. Attach the original headlight 3-prong connector that comes from the
bike into the 3-prong receptacle on the little extension cord that comes out of
the side of the modulator.
Replace the headlight assembly and attach it by
tightening the screw in the bottom of the bezel. It’s easy to over tighten
this, so be careful or you’ll strip the threads. Congratulations, you’re all
done! Start the bike and turn on the high beam, and after about a second the
headlight will start to modulate. Life is good!
One thing to remember, you need to be in enough light so that the sensor
doesn’t prevent the headlight from modulating. If you flick on the high beams
and the headlight doesn’t modulate, you may not have enough light in your
garage or wherever you’re working. The sensor seems pretty sensitive, so even
though I had an overhead bulb on in my garage at night while I was working, it
didn’t come on until I turned on another light. Try waving your hand above the
sensor to see how it turns the modulator on and off.
Visitor "D.H" installed a Kisan headlight modulator on a Honda VTX 1300C.
This bike has a plastic chromed headlight bucket, which makes for a tricky
installation of the ambient light detector. If you have this type of
headlight, you may need to use this procedure. D.H. writes:
I just now successfully installed a Kisan P115W in a
2004 Honda VTX-1300 C, and..... I suspect, that this new twist may be
more common than to just this one bike. Since the change over from
thin steel & chrome parts to plastic & chrome, the install scenario
changes somewhat. None of the supplied mounting information, and
the split bushing will help. The headlight assembly on the Honda
is made of thick plastic, and chromed. The thickness is just short
of 1/4 inch at the nominal top location on the headlight body. The
supplied "split bushing" will not lock in place, as it was made for thin
So, with a very slight modification to the non-optical
end of the Day Light sensor cable, the whole unit will fit very nicely
in a 5/16" (no larger) diamete hole.
I recommend placing a piece of tape, or adhesive strip
similar to a band-aid on the area that you plan to drill the hole.
This is to keep the chrome film from tearing, while the drilling occurs.
Of course, care must be also used when removing the tape, so as not to
pull off the chrome film in the process.
Tape in place, now drill the hole per your own
recommendations..... starting smaller, and working up (no oil
needed)..... but NO LARGER than 5/16" diameter.
Carefully deburr, and remove tape slowly. Clean
hole and surrounding area of debris, both top, and inside the headlight
Now for the modification: (this part needs to be
modified, as the plug end, in it's present configuration, will not fit
through a 5/16" diameter hole.)
The Sensor Plug, at the other end of the Optical (sun
sensor) cable has a "small depress tab", which allows the plug to be
locked in place into the Polarized Sensor socket of the PathBlazer (this
is the unit that has the "T" plate that can become very hot, per
comments by manufacturer). Just above, and to the left, and right
of that "small depress tab", are two small plastic molded stops, which
would prevent the "small depress tab" from being lifted up too far.
In the actual operation of this assembly, there is no reason why you
would ever want to 'LIFT" that "small depress tab", so these are, for
all practical purposes, not required. Using your thumbnail, pull
each of the two plastic stops off/they break off quite easily.
Now the rest is quite easy. Just slide the entire
cable into the hole, starting from the top outside of the headlight
housing, plug end first. Stretch some Mylar tape, or similar
material on top of the sensor (to hold it in place), and pot, with a
silicone glue, or similar material, the area around the protruding brass
colored collar from the inside of the housing. I would recommend
letting this assembly dry completely, before progressing to the final
install process, per the instructions included with the product.
The beauty of this assembly is.... that it's completely
waterproof, and quite stable, as the housing has a fair amount of
This note was prompted by the mere thought of other
folks drilling the suggested diameter hole into their beloved bikes.....
only to find out, too late, that the supplied parts won't work. Ugh!! "
Thanks for the tip, D.H.!
1. "Motorcycle Accident Cause Factors and Identification of
Countermeasures", Volume I: Technical Report, Hurt, H.H., Ouellet, J.V. and
Thom, D.R., Traffic Safety Center, University of Southern California, Los
2. U.S. Department of Transportation, National Highway Traffic Safety
Administration. Federal Motor Vehicle Safety Standards 49 CFR Part 571, Docket
No. 97-87; Notice 1. Executive Order 12866 (Federal Register: February 21, 1996,
Volume 61, No. 35). Here is a
copy of this document on a webBikeWorld page;
is a one-page copy you can take with you on your bike in case you get
stopped by an uninformed LEO.
Some Sources for Headlight Modulators