tach question

Got a question, i have a sunpro tach out of a car i had a while ago. it has a switch to select the number of cylinders its hooked to.my question is, is there a certain way it needs to be hooked to a motorcycle, being that the ignition systems are different, and how do you do it? thanks

Here's some info about installing a tach on a kawasaki cruiser that might work for your situation:

www.gadgetjq.com/tach_install.htm

Here's some info I posted a few weeks ago.

nelson8708 wrote:

I searched but, didn't find anything on putting an aftermarket tach on my bike (kz550). I was just wondering since its a waste spark system wont a regular tach from auto zone or something read double the actual rpm since it fires twice per rpm? I was thinking something along these lines...

^sunpro mini tach (2.25" diameter)

You are correct that the reading will be off by a factor of two (when set to the 4cyl setting). The Gauge will show the RPM as half of what the motor is actually doing. This is because you would only be connected to one coil and getting half the firings.

To correct for that, you need an adapter to get signals for both coils.

Here is what I use with my Sunpro Minitach.

Those are pretty heavy duty diodes. You can get away with lower amperage diodes, but they have to be high voltage. You want at least 600v diodes. The voltage rating will be PIV or PRV (peak inverse or reverse voltage).

(This adapter won't work with the DYNA S ignition system. That requires a slightly different adapter.)

The biggest problem with those tachs is that they are not made to handle a lot of vibration. They are made ot be mounted inside a car... very different from a motorcycle handle bar in terms of vibration.

They work for awhile, though. I took mine apart and hot-glued the internal parts and that helped. I've got near 10 years on my Sunpro now.