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Discussion Starter #1
Installed a tachometer on my 2006 C90 Boulevard this weekend. Seemed to be working in garage. Took to work this am, at 80 mph was only reading 1600 rpm's. Any ideas? 4 wires, 1-ground, 1-backlight, 1-hot, and 1 - neg wire to coil. All hooked up just as diagram shows. Generic tach that was bought over a year ago, cant remember maker.
 

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On the C50 or C90 each spark has a separate circuit so one tap provides 1 spark per cycle sounds like you are using a tack for the more common motorcycle dual fire spark systems which fire twice on each cycle with only one of the sparks actually igniting gas and the second spark firing the other cylinder. So the tack expects two fires per rpm, It's called dual fire and it's quite common. They make adapters to adapt dual fire tacks when used on a single fire system like the C90. You pick up the second spark signal per RPM from the other cylinders coil with the adapter doubling your RPM reading.

The C50 and C90 sparks are individually computer controlled for each cylinder which makes possible more accurate firing of the plugs.
 

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Discussion Starter #3
So, basically rather than opening things up again. If I just multiply the reading times two? Right?
 

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So, basically rather than opening things up again. If I just multiply the reading times two? Right?
My OCD says "fixit" :curse::boozin::smoking: You can buy a single fire adapter and hook it up to each of the coils with piggy back adpaters or make your own.

Here is a link with a diagram of the connection and parts on how to how to make the adpater for a few bucks. (it doesnt show the piggy back connectors at the ignition coils but that should be easy enough to figure out) http://www.volusiariders.com/60-help/225478-oem-tach.html

I have this type of adapter on my tach and I have a very slight needle bounce at idle ONLY and it works like a charm otherwise.

No need to remove the tank completely .You only need to lift the tank and remove the neck covers. Long needle nose pliers will come in very handy for the disconnect/reconnect.
 

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So, basically rather than opening things up again. If I just multiply the reading times two? Right?
Right.

And somewhere down the road you might find splicing in a new single fire tachometer A lot easier than opening up to the coils in order to add a single fire adapter. But for now I would enjoy your new tachometer :wayhappy: and just double the reading.
 

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LMAO to me that would be like not putting the black tape over the flashing 12am light on my old VCR.
 

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If you feel you wired it correctly, can you get to the circuit board in the tach, there may be a dip switch or a jumper wire arrangement on it for 2,4,6 and on cars 8 cylinder engines.
 

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You can also splice into the correct wire directly off the "ignitor" which is far more accessible than getting to the coils. I forget which color I spliced into.
 

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I have the C50 it has an ECM telling the ignition coil when to fire the wires are w and b/y
(pins 52 and 43) When working near or with the ECM you have to be really careful as a screw up can be really costly.
Do not use ohmmeter on ECM as it can damage the ECM

Some of the service manual warnings.
• Never connect any tester (voltmeter, ohmmeter, or whatever)
to the ECM when its coupler is disconnected.
Otherwise, damage to ECM may result.
• Never connect an ohmmeter to the ECM with its coupler connected.
If attempted, damage to ECM or sensors may result.
• Be sure to use a specified voltmeter/ohmmeter. Otherwise,
accurate measurements may not be obtained and personal
injury may result.


For the earlier volusia igniter system the ignition coil are connect by wires w and b/y also

Don't know the C90 ignition coil wires but they may also be w and b/y

w = white b/y =Black with yellow tracer

So If you can get to the Igniter or ECM (under the Seat) and splice into the other end of the wire connecting to the ignition coils (without removing the Fuel Tank etc) it might be a lot easier to hook up a tachometer. As an example my local MC shop charges $150 to wire in a tachometer with most of the cost in getting to the hard to get to ignition coils, removing seats, fuel tank etc. they of course are supper cautious as scratching the tank could be a costly problem.
 

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Discussion Starter #13
Ok Im baffeled. Finally got around to installing my baron tach adapter. Instructions said one of the bikes it worked on was a C90. Installed it.....tach background light lit up, that was it, needle wound up when turned on, then back to zero. Removed tach adapter, everything worked liked before, only read half correct. Totally confused...
 

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Where you say the "needle wound up when turned on, then back to zero", is that with the ignition on and the bike NOT running, or after the bike is started? The mini-tach I installed will sweep all the way to 8000 RPM when I turn on the ignition, but after a second or two it returns to zero and behaves normally.
 

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Most modern gauges do that sweep. It happens in the Kenworth W900L I drive on my IT job vacation and it happens on my Volusia if you disconnect the speedometer while removing the tank and then put it back on. My F-150 does it if battery is lost also.
 
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