electric tachometer on small engine?

[weirdarmadillo]

I picked up a tach from my uncles garage. Can I hook this up to a small enginne somehow and make it work? Just curious, Roman

http://i665.photobucket.com/albums/vv16/weirdarmadillo/FriJan01140653PST2010.jpg

[weirdarmadillo]

Here's the wire ends
This phone takes pretty good pics!

http://i665.photobucket.com/albums/vv16/weirdarmadillo/FriJan01140701PST2010.jpg

[ed1380]

hope this helps
http://www.offroaders.com/tech/Autogage-Tachometer.htm

[Russ2251]

Tach is made for multi-cylinder engines. Something must be added for operation on a single cylinder.

[Rotore]

Will give you a reading but it'll incorrect but still would look cool

[mike75925]

correct me if i'm wrong, but a tach is a tach. single or multi should not apply. they either read the crank or the cam (that i have ever seen or heard). seems some parts are missing (the magnet/sensor etc), but other than that it should be fine for any engine.

[Russ2251]

correct me if i'm wrong, but a tach is a tach.A tach is indeed a tach...but if set up to read a 6 cylinder ignition pulses, it can't possibly read correctly for 1 cylinder.
Read the link that ed1380 posted.
Locate the dips switches on the circuit board. Move each of the two switches to the proper cylinder selection according to the diagram illustration on the right.

4 Cyl. - Both switches down
6 Cyl. - Switch #1 down. Switch #2 up
8 Cyl.- Both switches up

4 cylinders minimum.

[mike75925]

why not just run it with the magnet like the bike's speedo? in a world where things are so easy, someone decided to make things harder. so does this thing have multiple inputs or what? just run the wire to one plug wire, if that is the type you are saying this is. if it is a lost spark ignition, divide by 2 to get true rpm.

[Rotore]

Yup works but wont read right

[mike75925]

ok, why?

[freakboy]

it was made for more then one cylinder... which means the board has the info for all the pulses and calculates the certain rpm... you can use it on a twin cylinder but you have to divide the information read in half.... dante brought it up a while ago that if you want a tach you should get a old mechanical one..

[Russ2251]

I use a tiny tach (http://www.tinytach.com/tinytach/commercial.php) and works great.
The only reason I use one is to calculate MPH.

[Kaptain Krunch]

I have never liked digital tachs personally, but they are the easiest solution if you want to know your rpm. I supposed i just like the looks of a old analog ones.

You can find mechanical tachs fairly cheap, i think surplus center sells them for under $20, they will be a little more of a challenge to hook up but i dont see why one wouldnt work.

[anderkart]

Tachs made for automobile engines like yours probably is... conect to the negative side of the ignition coil to monitor the engines speed. They also usualy require a 12-volt DC power/ground source to function. These tachs are usualy calibrated for either 4, 6, or 8 cylinder engines. Some tachs have a switch that can be set to match the number of cylinders the engine has. But all electric tachs have to be calibrated for the # of cylinders the engine has.

If you had a suitable battery to power this tach, it would most likely function on a single cylinder engine when its green trigger wire was connected to your engines kill switch wire. But depending on what # of cylinders it was made for, you'd end up getting a reading lower than your actual RPM. If it was made for a V-8, it would read 1/8th of what it should. If its for a 6 cylinder it would only read out 1/6th, a 4 cyl. tach would only read 1/4th.

With the wire colors you've got there, I'd have to assume your:
Red would be battery +.
Black = Battery ground.
Green = coil negative terminal.
white = would power the tachs internal illumination light for night time driving. In a car this wire would be connected to the dash light circuit but you could simply conect it along with your red wire if you wanted the light to function. (you'd need some means to disconect both your red/white wires when not in use or they would cause a drain and eventually run your battery down.

[Thunderbird SC]

the tach i have is one from an early 80's Yamaha 440 sled. Its a mechanical cable driven one which means I still have to machine a fitting onto my clutch hold down bolt. Then route it back to my dash area. Oh, I cant use that tach anyway, I'd peg that easily:wai:

[anderkart]

the tach i have is one from an early 80's Yamaha 440 sled. Its a mechanical cable driven one which means I still have to machine a fitting onto my clutch hold down bolt. Then route it back to my dash area. Oh, I cant use that tach anyway, I'd peg that easily:wai:

I've never done a mod like this but don't cable driven tachs use some form of gear reduction for the spinning cable? Doesn't seem like a drive cable would last very long spinning even just at 3600rpm, let alone the rpms some 2-strokes reach.

[Kaptain Krunch]

The cable driven tach on my Kz400 engine is run off the cam, not sure the exact reduction. I know some have a 2:1 drive reduction.

[Kenny_McCormic]

A 99mph bike speedo makes a fine 9.9K rpm tack on anything that spins with a magnet on it(your flywheel). You just have to set the wheel diameter to some funky number.