AWESOME go kart tach from northerntool

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Doc Sprocket

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That would work well for a kart- it is similar to the Tiny Tach, a unit that has been widely used on single cylinder engines. My biggest complaints about these units is the small, dark display (hard to read at 45MPH on a gravel road) and the digital aspect. I find analog sweep gauges to be a lot more user friendly and easier to read, as you don't have numbers jumping around- just an easy to follow, stable, meter.

That said, analog tachs that will work on a single cylinder engines are hard to come by. If you want a tach, this is a cheap and readily attainable unit.
 
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The no name Chinese ones on Ebay work well too for around $16 shipped. I use one on my generator.

They're inductive though - might be a bit of a stretch to run a wire from the plug all the way up to the steering wheel.
 
devino246

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kartingizm said:
nooooooooooooooooo something that reads the rpm and makes the gauge show how much rpm there is
Click to expand...

Actually, unless I read it wrong(and I may have since its crappy english), you'd just run a wire from the spark plug to the red wire. I wouldnt trust that though, plus it reads to 13,000rpm. The needle would hardly be moving.
 
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Screendoor

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Yeah I noticed it said 13000. Thats pretty high for my application. A new northern tool just went up here in va beach so I will probably just go buy the one from NT. Unless someone happens to find a cheap analog tach! Anybody have a link?
 
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Bike shops sometimes carry a bike speedo/tach. You put a magnet on one wheel (or other part connected to the axle) and a sensor picks up how many times the magnet passes by. This may be applicable to karts, but may not be precise enough for speeds higher than 30. Most can also calculate speed if you input the wheel diameter.
 
fowler

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isnt there a thread on the formular u enter to make those speedos into tachos?


they puit the magnet on the fly wheel i think?

these things will read the speed just fine

we used them on an elcectic car we built as a speedo and they were still responsive and correct at 60kph
 
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fowler said:
isnt there a thread on the formular u enter to make those speedos into tachos?


they puit the magnet on the fly wheel i think?
Click to expand...

The formula is simple. Find the circumference(Pi•Diameter) of your wheel in feet then multiply it by the RPM. This gets you the distance in a minute (in feet). Multiply that distance by 60 to get your distance (in feet) in an hour. To get miles per hour, divide that number by 5,280. That was all done in my head at 1:30 so double check my work. In the past I've put the magnet on either the wheel or even the brake disc, but the flywheel may work as well. Hope this helps, B
 
r97

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BAM said:
The formula is simple. Find the circumference(Pi•Diameter) of your wheel in feet then multiply it by the RPM. This gets you the distance in a minute (in feet). Multiply that distance by 60 to get your distance (in feet) in an hour. To get miles per hour, divide that number by 5,280. That was all done in my head at 1:30 so double check my work. In the past I've put the magnet on either the wheel or even the brake disc, but the flywheel may work as well. Hope this helps, B
Click to expand...

fowler said:
isnt there a thread on the formular u enter to make those speedos into tachos?


they puit the magnet on the fly wheel i think?

these things will read the speed just fine

we used them on an elcectic car we built as a speedo and they were still responsive and correct at 60kph
Click to expand...

BAM said:
Bike shops sometimes carry a bike speedo/tach. You put a magnet on one wheel (or other part connected to the axle) and a sensor picks up how many times the magnet passes by. This may be applicable to karts, but may not be precise enough for speeds higher than 30. Most can also calculate speed if you input the wheel diameter.
Click to expand...

r97 said:
would probably need a battery, more wiring, a sender unit, and maybe some more circuitry.

check this out:

http://www.diygokarts.com/vb/showthread.php?t=10006


_________________________

you could probably rig up a bike computer to work as a tachometer
Click to expand...

:D

i would not suggest rigging anything up to the flywheel.

put the magnet on your wheel, sprocket, or brake. then just factor in the karts gear ratio. with the right numbers plugged into the computer you can make the screen read "36mph" but actually be telling you the engine is at 3600rpm. that make sense? the formula shouldn't be too complicated to figure out.

to get you started with the formula, figure out how many feet you go for every 100rpm of the engine. then divide that number by 3.14, thats the dia of the wheel to type into the computer. (note, you computer may want the circumference, or radius instead).

a kart with 12" tires, a 6:1 gear ratio.

100rpm / 6 = 16.6 axle rpm

12" * 3.14 = 40.8"

16.6 * 40.8 = 677.28" of travel per 100 engine revolutions

677.28 / 3.14 = 215.7" dia of rear wheel to plug into calculator.

i'm pretty sure that formula would work, you can test it if you want.
 
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