Author Options:

Can I use a regular digital thermometer as a cylinder heat temp gauge? Answered

Hey guys,

I want to make a cheap cylinder head temperature gauge for my 150cc scooter. I have owned one before which worked well but it was rather expensive. I'm more interested in being able to detect a temperature spike and avoid a blown motor than determining an acurate temperature. The last gauge I owned used a probe with a ring on the end that acted as a washer between the spark plug and the head.

If I buy one of these probes:

And a digital thermometer with a probe like this:

Could I just splice the wires together and be away laughing? I'd need to find out what the temp range of my engine is first.....my last 2-stroke 150cc ran at about 275F and melted at 400F, 4-strokes should run cooler right?

Any thoughts would be appreciated :)


The Skinnerz

7 years ago

Different thermocouples will generate different voltages at the same temperature, so it is unlikely that you will be able to use that one accurately. If you are lucky, the new thermocouple will fit on the scale of the meter, so that way you just need to calibrate a few values.

The best thing to do would be to see if you can find the specification of a thermocouple that is matched to the meter, and match whatever you buy to that.

Alternatively, you could stick the supplied thermocouple around a grooved ring, giving a perfect match.

tig5The Skinnerz

Answer 7 years ago

Thanks for that info :)
I have found K-type thermometers with probe inputs and k-type sensor rings. As far as I can tell the "type" refers to the temperature to millivolt conversion.....so theorhetically if I used these together id be ok?
Like I said, I'm more concerned about seeing temp change than actual temp.
Thanks again for the info

The Skinnerztig5

Answer 7 years ago

Providing the mV/degree conversion is in the same sort of range, you should be able to use it with your meter well enough to tell when the head reaches a certain temperature.