Tachometer Installation

Who the heck needs a tachometer on a cruiser? Well, probably nobody but it's really sort of fun watching your engine lope along at 70 mph at 2500 rpm and you'll quickly realize you've been running your big 1500 or 1600 a lot slower than you'd thought around town. (Anybody want to fess up to hitting 4th on a city street? Thought not)

This is a very simple install. The hardest part, removing the gas tank (on the 1500 FI, not necessary on the 1600) which really works better with two people, one to hold the tank the other to disconnect the hoses and wiring connectors. The wiring is extremely simple.

1. A tachometer. Barons offers a beautiful billet model priced at the higher end of the scale while Drag Specialties gets the job done on the low end. The links are just so you can see photos, shop around for best pricing.

2. A "multistack connector" (photo right). Don't panic you've probably seen these before on Volkswagen bugs and that's where you'll find them, any VW (or sand buggy) outlet and many ordinary auto supply stores. This connector makes attaching your tach to the coil very simple.

6. If your bike (VN2000 or VN900) has single fire ignition (spark plug fires every other revolution) you'll need a 'single fire adapter'. You can purchase them almost anyplace motorcycle tachs are sold and Barons throws one in the box with each tach purchase. You can make your own with less than a dollars worth of materials and while it isn't as sophisticated as the Barons unit (you may see some needle flutter at idle) it 'should' work for you. You'll find instructions here.

1. Determine how you want to mount your tach. If you looked at the vendor links above you noticed it can simply be clamped to your handlebar or you can spend some extra dough and get a spiffy housing that replaces the top cap on your risers. Mount the tach whichever way you prefer.

2. There will be four wires coming out of the tach housing. The color may vary depending on the maker but one will be ground, another goes to one of your coils and two will run to power. Got em? Remove your headlight front ring (two Phillips type screws, one on each side) and pull the plug on the headlight bulb. Set the assembly in a safe place (not on the garage floor you'll most certainly trip over it)

3. Run the tach wiring harness into the housing and (if provided) trim back the black plastic covering on the wires until you only have a couple of inches inside the housing.

4. Look for a black wire with yellow stripe. This is Kawasaki's ground (there are several) one is really handy running to the headlight bulb. I suggest soldering connections but if you prefer you can use the clamp type wire connectors (available at any automotive store). Determine how much of the ground wire coming from the tach you need to easily reach the bike ground wire you've chosen. Trim it to length and attach.

5. Using your multimeter or test light, find a + wire inside the housing that is "switched". The easy one is gray and goes to your front running lights, one on each side. Whatever you choose test to be sure the power is off when the key is off and on when the ignition is on. This will power your tach and the light inside. Trim your hot wires from the tach to length and attach to the + wire in the headlight bucket you've chosen. When finished turn on your key. The light in the tach should be on. Got it? Go to step 6. If not go back and check your connections.

6. You have one wire left and it goes to one of the coils. (which one doesn't matter) For this you'll have to remove your tank or at least move it back a few inches on a 1500 Nomad or Classic. On carbed Vulcans this is a piece o' cake. Remove your instrument cluster, remove the seat, remove the bolts holding the tank front and rear, disconnect the fuel line from the petcock, lift tank and set aside in a safe place. Owners of 1600's have easy access to both coils as they sort of peek out from under each side of the tank so those owners can just skip ahead to step 7.

The FI tank is a little tougher and really helps to have someone assisting you. You'll be removing the instrument cluster (study the electrical connectors to determine what you have to press down to release). Remove the seat and two nuts holding the tank to the bike. Pull off the one (49 state) or two (California) small hoses from the rear of the tank. Lift the tank from one side of the bike and have your helper disconnect the hoses from the other. At this point you can try to move the tank rearward a few inches for access to the coils. If you can see them and get to them then go straight to step 7. If not lets get the tank off. The vent hoses are pretty obvious, the pressurized fuel line can sometimes be a little stubborn. Press in on both sides of the connector (rectangular buttons) and wiggle the connector loose. There are two more wiring connectors under the tank. One of these comes right apart the other has three (countem) latches that have to be pressed for the pieces to release. There's probably a special tool for this but two small screwdrivers (one wedged into the top latch while you press the others with a second screwdriver and wiggle) get it done. You did siphon most of the gas out of the tank right? If not the tank holder needs a beer now. Take a break.

7. Using a flashlight (unless you have terrific garage lighting) peer down inside the frame from directly above on a 1500, up from below on a 1600. Spark plug wires are going into the front of each of the coils. Got em? Now look for the black wire which is connected with a standard female flat connector. The assembly line can't seem to decide which side up to mount the coils so some Vulcans have the black (negative) wire on top, some on the bottom. Even same year bikes seem to be different. At any rate whichever side the black wire is on is where you'll connect your tach wire. If you can't find the black wire it's time to dig out the tester again. Turn on the ignition and test both sides of the coil. One side will show 12V +. You want the other side. The coil on the right side (#2) is a little easier to get your fingers or needle nose pliers on if you're working on a 1500 but the left side coil is easier to reach on a 1600. Remove the black wire and replace it with the "multi" connector discussed earlier. Now re-connect the wire you just removed. Note there's no doubt some riders have simply removed the connector, stuck the tach wire inside then pressed it back on the coil. Not very elegant but it'll work.

8. Run the appropriate tach wire back out of the headlight housing (sheathed in shrink tubing makes it look better) back along the left side of the bike (path along the stock wiring) and to the coil. Connect a female flat crimp type connector to the wire and attach it to the other male connector on the multi connector.

9. Your assembly is complete. Just put the tank back on (FI riders listen for a soft "click" when attaching the pressurized fuel line). If all the lines are connected (including wiring at the bottom of the FI tank that powers the fuel pump) the bike will run without the instrument cluster in place. Fire it up and make sure the tach is working. Yes? Button it all up and go for a ride.

The 1500/1600 Vulcans use a dual fire or 'wasted spark' ignition system that provides a pulse from the coil every revolution of the engine. The 900 and 2000 engines are 'single fire' meaning the spark plug only fires every other revolution for the power stroke (same as most cars).

The problem: the majority of motorcycle tachometers are designed to work with dual fire ignitions.

The solution: A dual fire adapter that takes pulses from both coils and feeds them to the tach.

You can purchase dual fire adapters almost anyplace motorcycle tachs are sold. Barons has them Mr. Fabrication has them (midway down the page) and there are others. Barons throws one in with every tach purchase so no worries if you're buying one of their very high quality units. If it bothers you to pay $20 or more for something you can make yourself for about a buck then read on.

All a tach adapter does is send the pulse signal from the negative side of both coils to the single wire of the tach thus doubling the number of pulses (and making the tach think it's working with a dual fire ignition.

1- foot of 18 gauge wire (any color)
2- 1N4007 Diodes (Radio Shack)
2- 100 k ohm resistors
Shrink tubing

Take a look at the diagram at left (click for larger image). It's just an ultra

single_fire_tach_adapter.gif (12749 bytes)

simple circuit that allows power to pass 'from' the coils to the tach but the diode prevents it from moving backward from one coil to the other. The resistor smooths out the power delivery (eliminating spikes) but the resistance prevents one coil from being affected by the other. You 'must' use both.

Notice the way the arrow points in the diode diagram. That shows the direction the power flows. It can 'not' flow backward. If you reverse the diode the circuit won't work. So how can you tell? Not a problem. Check out the picture at right. The diode will have an off center silver band on it. The power flows toward the band as shown in the picture.

When you're finished you'll have a little assembly that looks like the picture at left. See? Simple! Solder the twisted ends and add a short length (couple of inches) of wire then put shrink tubing around everything so you isolate the two sides and protect against abrasion. Add appropriate connectors to the wire (dictated by whatever you're using to connect to the coils and to the tach wire). You'll end up with a harness that looks a whole lot like the example at right.

Connect the two 'coil' side wires to the negative side of your coil. How can you tell which is which? The negative side will always have a dissimilar color wire from the other coil. In other words, both positive wires will be the same color, the negative wires you're interested in are the two odd colors. Once connected to your coils using the same type connectors as shown for the 1500/1600's above connect the 'tach' side wire to whatever color wire from your tachometer (usually green but not always) is supposed to attach to the coil.

The Parts	Twisted Together. Note orientation of Diode So Electricity only Flows One Direction Toward Tach	Soldered
Add Shrink Tubing To Each Leg	Add Shrink Tubing Over Entire Assembly	Attach Appropriate Connectors. Done!

Make sure all your wiring is tucked up out of the way so it won't rub on any engine part or be abraded by the frame. Gentlemen (and ladies) start your engines! If, for some reason your tach still reads half the rpm it should or if it doesn't work at all recheck the orientation of the diodes.