Non contact digital small engine tachometer

[oldcarcbx]

Does any one have experience or suggestions regarding non contact digital small engine tachometers , how accurate and reliable are they?

I see them on Ebay as low as $15 and as much $170.

 

[ole4]

are you looking at the optical ones? I used to use them on my model airplane engines and they work well. Post a link to the one you are looking at.

 

[cfh]

i've used one of them there ebay units. at low rpm i'm not sure how accurate it is. but at 2000+ it seems to be decent. It's not 100% but it gives you a good idea where you're at. One of the variables in using them is how many turns the tach wire goes around the spark plug wire. you have to play around a bit but i found 6 turns worked for me.
https://www.amazon.com/Maintenance-...2951080&sprefix=mini+bike+tac,aps,171&sr=8-12

 

[oldcarcbx]

The type of tach i was looking at resembles a non contact thermometer which reads via a beam which "bounces" back to the source and provides a reading.

Thanks for your replies