fitting a rev gauge

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kibble

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I just saw in Harbor Frieght's flyer that they have some gauges and one is a tach, item number is 98480, and sells for $19.99. Measures up to 8000 RPM. Unfortunately, they don't have more info on them and they aren't on the website yet.

For that price, I was thinking of getting one and playing with it. It it were to connect to the crank output sensor of a car, hooking it up to a single cyl engine should be no issue.
 
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Usually tach's connect to the "tacho" signal from the ignitor, or the low voltage side of the coil. That's why you have to cut certain wires to select 4/6/8 cylinder cars. A 4 cylinder car tacho will work on a twin cylinder bike because they use a waste spark system.
You could use a car tacho on a single cylinder, but it will only show half the speed (if it's waste spark, if not then it will show 1/4 the speed). The tacho will show most industrial engines pegged at less than 2000rpm, lol.

Or... I could be completely wrong and this tacho uses a different system.
Needle tacho's are SO awesome on karts. I was given an AutoMeter 6" monster tacho with a shift lite... but the shift lite has been removed and the signal used for an adjustable rev limiter. I hope it works.
 
robin

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Russ2251 said:
Works on minimum of 3 cylinders.
Click to expand...


i would asume it conects to the coil if so becuse my engin fires every tdc could i not set it to the 4 cilender setting then just dobble the revs so at 5 k on the gauge my engin would be at 10 ?
 
kibble

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All of which can be found at your local Pep Boys store.
 
robin

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im realy thinking about spinners lol im sure i could come up with something in work on the cnc it would be realy easy just tap a bolt on the end of my axle

my friend has a cherry bomb 4 inch exhaust of his car he is selling it for 20 quid i might just have to nab it
 
Raywelder

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kibble said:
I just saw in Harbor Frieght's flyer that they have some gauges and one is a tach, item number is 98480, and sells for $19.99. Measures up to 8000 RPM. Unfortunately, they don't have more info on them and they aren't on the website yet.

For that price, I was thinking of getting one and playing with it. It it were to connect to the crank output sensor of a car, hooking it up to a single cyl engine should be no issue.
Click to expand...

This thread is a bit old,
But I thought I'd add that harbor freight has those gauges on there site now,
They are led lit with 7 different color settings I believe.
http://www.harborfreight.com/cpi/ctaf/Category.taf?f=bylogo&logourl=nitrous.gif&brand=Nitrous
 
Raywelder

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How are they wired? Like for example, if there were 4 wires to hook to a 4cly, couldn't you just double up the wires for a twin? I think I may get one for my twin mini project, and will probably definaintly get one for the bike engine go cart project.
 
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It doesn't work like that. 1 wire is the 'tach input', one is usually +12V, one is ground (-12V), and one is the illumination wire. A 4 cyl car tacho should work fine on a twin cylinder motorbike engine because they use a waste fire spark system.
 
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