Hand held tach. how do they work?

[WhyMe]

i was reading that the best way to adjust a 2 cycle engine is with a tach. i see non contact tachs on ebay.

So how do they work? how does it measure on a 2 cycle engine?

 

[Jagmandave]

It works off the vibrations of the engine - the resonant frequency causes a sympathetic vibration in the meter. At least that's how they worked back in the day.....they weren't terribly accurate tho.

I understand there are digital ones that use frickin lasers now.

 

[Journaler]

It works off the vibrations of the engine - the resomant frequency causes a sympathetic virbration in the meter.

That is obviously a lie. Everybody knows these non-contact tachs use witchcraft.

 

[alan_3301]

The only kind I've seen work off of a led transmitter/receiver.
Your paint a line with whiteout on a spinning object, and every time it comes around, it triggers the receiver.

 

[biscuit141]

I believe these work off the electric pulses through the spark plug wire. I could be wrong though. I need one of these. Did you find a place that sells them at a good price? Link?

 

[APEowner]

I have two non-contact tachs. One uses an IR emitter/reciever combo to count pulses off a reflective tape (or really anything else shiny). The other (which I much prefer) uses the pulses off the plug wire.

 

[ilovevocs]

Just curious what you need a tach to adjust?

 

[Mohawk Dave]

.....ones that use frickin lasers now.

"Frickin lasers..."

 

[djjsr]

I use this one. It has a switch for 2 or 4 stroke.

 

[biscuit141]

Where is the best place to buy? I really need one of these for adjusting chainsaws.

 

[djjsr]

It's called an EZ Tach. I got mine at a motorcycle shop a long time ago but you can probably find it on ebay or amazon. I think there is another company that makes them as well. Just be sure the one you choose is ok for a 2 stroke.

 

[TheGrooveking]

I have an Extech that does both contact and non-contact, I use it from feet per minute to rpm for a wide range of applications.

TheGrooveking

 

[WhyMe]

Just curious what you need a tach to adjust?

Chainsaw and string trimmer.

 

[Danglerb]

HF has one, no idea if its good.

 

[cryan]

I've used the reflective tape that you stick on the flywheel. Problem is keeping it stuck on. You have to really degrease good or it just falls off.