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testing a tachos accuracy

For all things Electrical.

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testing a tachos accuracy

Post by j-top paj »

got a tacho on the boat for my outboard, but how do i test to see if its accurate?
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Post by j-top paj »

i was thinking of hooking it up to another tacho i have and compare the two.
its a 3cyl 2 stroke, so do i set the other tacho to 6cyl and just halve it?
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Post by chimpboy »

j-top paj wrote:i was thinking of hooking it up to another tacho i have and compare the two.
its a 3cyl 2 stroke, so do i set the other tacho to 6cyl and just halve it?
That should work, but I think it will be doubling the reading not halving it. Anyway you'll be able to tell pretty easily.
This is not legal advice.
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Post by j-top paj »

it doesnt have to be spot on, just enough so i can figure out where the motor is most economical
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Post by -Scott- »

A four stroke fires each cylinder every second revolution; a two stroke fires every revolution.

3 cylinder 2 stroke & 6 cylinder 4 stroke should both fire three spark plugs every revolution.
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Post by j-top paj »

so if its set to 6cyl then it should give an accurate reading?
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Post by its aford not a nissan »

dont outboards have seperate coils for each cyl??
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Post by j-top paj »

yeh mine does..
but there is a plug on the control box up front that has all the wires for the tacho.
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Post by -Scott- »

Each coil will fire only once per revolution, so your pulse rate will be the same as a 2 cylinder 4 stroke.

I'm not sure what to do there.
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Post by j-top paj »

all sorted, thanks guys

there is a single trigger wire from the control box,
the tacho was only out by a little bit
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