How to determine RPM?

geohorn

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Anyone with an idea how to determine the RPM? IN other words, without a tachometer how to do it? And how would a tach attach? (RTV-X900)
 

California

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I like the Old-School

Briggs & Stratton 19200 Tachometer

It has a wire that extends like a tape measure with a scale that shows rpm, proportional to how much wire you have extended at the point where the wire vibrates in resonance with the engine vibration. Handy, indestructible, ageless. This should be in the toolkit of anyone maintaining a variety of powered equipment.

Its accurate, it matches what shows on my tractors' tachs.
61i4yRIblcL._AC_UL115_.jpg
 

aurthuritis

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photo tach or hand held on the crank end or one that has a pickup that clamps on the injection line. or one of the above.
 

California

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I think the B&S tach is faster to set up and use. :)

Here's a 45 second Youtube video illustrating this.

You only need to see the first 25 seconds of the video. After that is a still photo showing the readout.

Get it out, take a measurement, put it away. All under 60 seconds.

No battery, its entirely mechanical.

Manufacturer says it "indicates with a tolerance of 1-2%"

This is one of those cases where a tool was invented long ago and nothing since has surpassed it.
 
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geohorn

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Thanks for the replies. I was wondering if there was a permanently-mounted unit available for RTVs, but I’ll try the B&S unit. My most important reason is to adjust the idle speed to the recommendation made in the manuals, but they don’t tell how to determine that RPM. :pat:

I believe the previous owner of my barely-used X900 had tried to make it idle very slowly because the safety-wire on the idle-adjustment screw was stretched, and the engine vibrated excessively IMO. I adjusted it to idle more smoothly but I would like to confirm its at the recommended speed.
 

aurthuritis

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Thanks for the replies. I was wondering if there was a permanently-mounted unit available for RTVs, but I’ll try the B&S unit. My most important reason is to adjust the idle speed to the recommendation made in the manuals, but they don’t tell how to determine that RPM. :pat:

I believe the previous owner of my barely-used X900 had tried to make it idle very slowly because the safety-wire on the idle-adjustment screw was stretched, and the engine vibrated excessively IMO. I adjusted it to idle more smoothly but I would like to confirm its at the recommended speed.

probably could find a tach off of another machine like a mower with the same engine as yours and transfer to your rtv???
 

geohorn

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Well, I ordered the Briggs & Stratton/Treysit unit and it arrived today.

I find it worthless. It simply does not give reliable information on this 3-cyl diesel. It vibrates it’s little wire at several RPM ranges such that one cannot be certain which is correct.

I tried in on my Kubota tractor (which has a tach) so I could determine how accurate the little unit might be... and it doesn’t depict any RPM at all when the tractor is running at 900 RPM.

I’m returning it and I’ll be looking for a different solution to measure RPM on my X900.
 

California

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Sorry to hear that, and surprised.

Its good to read that you can return it.
 
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