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The information on these pages is accurate to the best of the author's knowledge. The author can assume no responsibility for the use or misuse of this information by the reader. The reader is expected to secure any other information needed from Service Manuals or other sources. It is up to the reader to determine his/her ability to make any modifications noted. If the reader does not feel qualified he/she should enlist professional help.

Indicator lights on the Xc Bar Clamp!
Shift light and a blinker indicator shown here
Thanks to ataDude on the VTXOA board for the idea of using the clamp and LED's
Instructions are for the VTX c model. For Retro, adjust the method to suit
By Chet Walters


Indicator lights

MATERIALS
Harlan Shift light
22 guage 4 conductor phone wire
Super Bright LED's of your choice
Resistors and Diodes
LED holders (RS 276-080a)
Heat Shrink or Electrical tape
small zip ties
TOOLS
8m, 10m socket
6m Allen wrench
Solder and iron
knife or wire stripper
wire cutter
Hemostat
Hot glue or silicone
Click any picture to see enlargement
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STEP ONE: Remove and drill the bar clamp
Remove your seat. Remove the 8m nuts & washers from under the speedo. Lift the speedo out and pull the square grommet and unplug. Cover your tank with a double beach towel and remove the bar clamp. Set the bars on the tank and don't press the brake or clutch levers.

Move the clamp to the work bench. Drill two holes in the clamp as shown to fit your LED's. For the listed holders (Radio Shack 276-080a for 5mm T-¾ LED), drill 5/16" holes. Make sure the holes line up with the triangle blank spot under the clamp. At this time, silicone or hot glue into place the LED holders (the nut won't fit and hot glue works great).

STEP TWO: Prepare your wires
Using four conductor phone wire, strip and cut the wires. We will route the YELLOW and GREEN leads to one side and the RED and BLACK leads to the other side (you will see why in a minute). Trim one side shorter than the other and strip about ½ off the ends for soldering. You want your solid phone wire with the outside insulator intact to exit under the clamp about where the speedo wire exits as shown in the pic. Leave about three feet of intact wire so it can reach from the clamp under the tank to under the seat with enough slack for turns.
STEP THREE: Connect your LEDs to the wires.
Wire wrap is usually better for LEDs since they are heat shy, but for this application since they may get stressed a little, we will solder. When soldering LEDs, use a heat sink. Insert the LED into the black holder plugs first. Put some heat shrink down onto each wire and then solder the wires. Here we use GREEN as negative and YELLOW as positive on one LED and BLACK as negative with RED as positive on the other. Each LED will have the shorter lead as negative and longer as positive but if you cannot determine by that, each LED has a flat side at one of the leads to tell you that is the negative pole. After you solder, trim any excess off the leads then place and shrink the heat shrink.
STEP FOUR: Install the LED's.
Wait until your silicone dries overnight or if you used hot glue you can do this right away. Hold in the LED holders firmly in place with your finger then insert the long strung LED and plug into the holder on the side away from the speedo lead and insert the remaining one on the other side. Route the wires as shown so they won't get pinched and tape in place with electrical tape.
STEP FIVE: Re-install the clamp and route the phone wire.
Put your clamp back in place and install the speedo wires and speedo. Then route the phone wire down along the speedo wire and zip tie in place. Making sure you leave enough slack for turns, route the wire under your tank (raise the tank as necessary) and back to under your seat. Zip tie to the clutch pipe or as needed for a good look where it shows and to the frame member on the way back.
STEP SIX: For a turn signal indicator.
If you are making a single indicator for both signals, you need to make a little circuit beforehand using the diodes (Radio Shack 3AMP Epoxy Recitfiers 276-1144 work good) and a resistor. Make sure the diode band points toward the resistor and the other ends are isolated. Since we will be running 2 volt LEDs off 12 Volts, I chose to use a 560 ohm resistor. Anything less and the LED is too bright at night. Solder as shown and cover with shrink leaving the diode ends isolated and the resistor end leave enough to solder. Solder your resistor to the YELLOW lead of the phone wire. Under the right side cover in the transparent boot, connect one diode to your ORANGE signal lead and the other diode to the BLUE signal lead. You will probably have to use some 18 or 20 guage wire to reach and an easy way to connect to these can be seen if you click here. Connect the GREEN phone wire negatve lead for that side to a suitable ground on the frame. Do the smoke test. If it works, cool! If you are using one each for a signal light, then hook the RED to the BLUE and the YELLOW to the ORANGE and both the BLACK and GREEN to a ground. Try to make them coincide with right and left (reverse if necessary). You won't need the diodes in this case but you'll have to use a resistor on EACH positive lead or you'll blow the LED.

STEP SEVEN: For a shift light (mine is set at 5100 RPM).
I used the Harlan shift LIGHT, not the RPM counter, but here are details for both. First hook up the Harlan to your coil as described in Matt's instructions. Then.....

For the shift light: I simply cut the wires to the supplied LED cluster (I'm going to use the LED cluster on my trailer). The output is always hot 5 volts on RED and BLACK is negative (switched). Using a 47 OHM resistor in line off the red wire from the Harlan, solder to your RED phone wire lead. Connect the BLACK phone wire lead to the BLACK Harlan lead (you can't just ground it since Harlan switches the ground).
For the RPM counter: From the counter comes the switched WHITE wire as ground. Solder this directly to your BLACK phone wire lead. Using a 47 OHM resistor in line, you will need a 12v source to feed the positive side of the LED so find your BLACK/BROWN wire that feeds your tail light in the transparent boot under the right side cover and use that.

To seal the pipe of the unit, I used the supplied boot for the coil and power inputs like Matt shipped them. But for the shift light, since I used the LED cluster that sealed the unit's other end elswhere, I needed to plug up the open end. I just used a bottle cork of the right size. Vóila!

NOTES on LEDs: One can adjust the brightness of a raw LED by using resistors and resistors are NECESSARY when the supply voltage is larger than the LED voltage (or the LED will fry POP!). Typical LEDs have 2-3 volts and 20 mA which means that for 13v, one needs a resistor "by the book" of 530 Ohms to run the LED at long life and fair to good brightness. The formula for LEDs and resistors is SUPPLY_VOLTS minus SUM_OF_LED_VOLTS then divide by LED_AMPS = RESISTOR_OHMS. So, for single 2.4 volt LED which is 20mA used on a 13 volt bike you would use (13 - 2.4) / .020 or 10.6/.020 = 530 OHMs for the resistor. For multiple LEDs, add up the total voltage of the LEDs in a series and use one resistor for them all. In our example, two 2.4 volt LEDs at 20 mA would be > (13 - (2.4 + 2.4)) / .020 or 8.2 / .020 for a 450 OHM resistor. You should not exceed 80% of the supply voltage in doing this. If so, make two series circuts under the 80% figure and then parallel them together.

But, this is for optimum life of the LEDs under constant use. The LED will not show its max light output using the formula. For the signal indicator above, I chose the formula 530 OHMs and used the closest readily available resistor of 560 Ohms (it's not that critical). But, for a REALLY REALLY REALLY bright LED you can go WAY low on the resistance. I used a 47 OHM on the shift light even tho the formula > (5 - 2.4) / .020 < calls for 130 OHMs. The LED is bright as sunshine and very visible during the day, but it would not last very long under heavy use. Since the shift light is only on momentarily and very rarely, who cares how long it lasts, ya wanna SEE IT!

Here's a little program (Click LED.EXE) to download and use to get the resistor needed for your particular LED you want to light. Runs on any PC with VBRUN300 in the system folder (most will have that there). Remember, play with lower valued resistors than the formula calls for and get really bright displays.


Questions? Contact Chet at Chet says 'Be sure to write!'Chetspages@rattlebars.com