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LED (light-emitting diode) turn signals offer several advantages over incandescent, not the least of which are reliability and long life. Incandescent bulbs can burn out or break at the most inopportune times and LED bulbs are virtually immune to these issues.

LEDs also draw far less power than incandescent bulbs but remember, they only draw any power at all when they're on and, as you'll see later, you'll need to add resisters to effectively increase the power consumption back to that of incandescent bulbs anyway.

Selecting Bulbs 

fullerbike 34 signal fullerbike 34 signal

There are several options available for LED signals. You can replace your stock 1156- or 1157-type bulbs with similar bulbs, you could add run-turn-brake functionality with something from Custom Dynamics, or you could replace the entire assembly for a completely new look. This article will assume that you're looking for the simplest approach and will replace only the bulb.

Directional LED Not recommended - Directional LED

Not recommended

When you're selecting a replacement bulb for your stock signal housing you need to remember that the housing is designed for a bulb which throws light in all directions and makes use of the reflector. Some LED bulbs found in auto supply stores are highly directional and not well-suited for this purpose.

 

Superbrightleds.com is a recommended vendor for bright LEDs, but this one is not suitable for use in a motorcycle turn signal housing. In the case of the Mean Streak the bulb is mounted sideways in the housing, making matters even worse.

 

Omnidirectional LED Bulb Omnidirectional LED Bulb
Much better

You should look for this type of bulb, which throws its light in all directions, and get the brightest that you can find and that will fit your housing.

 

The output of an incandescent bulb is around 400 lumens while the bulb at the left puts out 220 lumens. Another option is rated at 550 lumens but you'll need to be sure that it will fit.

 

Installation

If you're replacing your stock bulbs with LEDs in the same fixtures you simply need to replace the bulbs and move on to the "Fast Blink" section below. If you're replacing the fixtures you'll need to cut and solder wires. Just remember that LEDs are polarized, meaning that they won't work if you mix up the positive and negative connections. LEDs also must have some load (resistor) in series with them. If you get a bare LED and connect it to a battery you will burn it out. Bulbs and kits typically have these built in but remember this if you're building something from scratch.

 

Fix the Fast Blink

Once you get your new LEDs installed you'll quickly find that your signals blink far faster than normal. This is a feature of your flasher designed to let you know when a bulb is burned out, which is exactly how the flasher sees the LED due to its much higher resistance.

The easiest option (if not the cheapest) might be to get an LED flasher for your bike. However, this may take away the auto-cancel function of your signals if you have that.

The other fix for this is a pair of load-equalizing resistors that will shunt current to ground, making the resistance and power draw seem normal to the flasher.

Amazon and Custom Dynamics offer ready-made resistors, or you can make your own (thanks to BareAssChoppers.com). If you want to figure out exactly what you need, check out the next page (Scary algebra warning). Otherwise find some in the 6 - 8 ohm range, around 50 watts, and just keep on reading...

Locating the Resistors

A little care must be given when installing the load equalizers since they can get hot. If you've ever held onto an illuminated bulb you know what happens; the resistor is doing the same thing. That additional power that it's drawing is being dissipated as heat.

A nice place on the Mean Streak is right next to the battery, where it's also easy to tap into the rear signal wires and the frame serves as a heat sink. Look for someplace with some air flow and avoid tucking them into the headlight bucket where they'd be likely to melt the insulation from other wires.

speed resistors speed resistorsconmar resistors conmar resistors

 

turn signal schematic turn signal schematicPerforming the Installation

Once you have a good location selected, locate the positive and negative wires. According to the schematic to the right (from the Mean Streak service manual), the negative wire is black/yellow and the positive is green (right) and grey (left). Strip off a bit of insulation from each wire and solder one lead of the resistor to the positive and one to the negative, for each signal. You can also use a frame ground in place of connecting to a negative wire, as long as you locate a good ground point.

Resistors are not polarized so the direction doesn't matter.

Remember, "heat the material, not the solder" to get a good connection. Using a heat-sink clip, or just an alligator clip, on the wires and resistor leads will help protect them from excessive heat.

 

When is a Diode Needed?

mdk diagram mdk diagramIf your bike has a single indicator light on the dash for both left and right signals, the resistors can cause that indicator to become a path between the two sides causing all four signals to flash. To fix this problem you need to add a pair of diodes into the circuit to ensure that current can't flow the wrong way through the indicator lamp. This diagram shows the installation of the diode kit from SuperBrightLEDs. If you purchased a "load equalizer kit", or built your own from BareAssChoppers, then you've already added diodes and this issue should be fixed.

Note that diodes are polarized, unlike the resistors, and won't work properly if they're installed backwards. They must be connected with the positive termal toward the turn signal power and the negative terminal (indicated by the line around the end representing "-") toward the indicator bulb. In this diagram the stock setup has the indicator bulb grounded through the other signal circuit. The change is to ground it to an actual ground and combine both positive signal leads to the same indicator lead.

(An interesting thing about incandescent bulbs... 1) they're not polarized and will work with current flowing in either direction; and 2) they have very low resistance such that a bulb can serve as a ground connection for another circuit.)