Sunday, April 07, 2024

Tool Review: Inductive Reading Tachometer

Recent work on Thing Two's pickup truck led me to wonder if the idle was set too high on the engine.  The truck didn't come with a tachometer however.

My mind then thought to get a tachometer that wasn't tied to a specific vehicle so I can use it to determine RPMs on any gasoline/two stroke or four stroke vehicle.

A little googling and I figured I'd try this one:

It's made in China by an outfit called Bohisen and cost me $15.43.

I thought it would work like a similar tachometer I'd used on my motorcycles previously.  You coil the far end of the wire onto one of the spark plug wires and when the engine is on, it tells you the RPMs.  Simple.

Well, this one is "mo better".

It takes inductive reading a step further and comes set from the factory to read four stroke engines and I imagine car engines.

The first step I used Yagi, my TW200 as test subject as Thing Two has retried the pickup truck for use.  I clamped it onto the spark plug wire and it worked.  Easy Peasy.

The instructions also say you can just hold the meter close to the spark plug wire and get a reading!  Yep.  No need for the clamp or wire if you don't want to use it. 

Not a bad tool for when working with a gas engine vehicle with no tachometer.

Update: Thing Two came home this morning so I was able to use the tachometer tool on the truck with the engine still warm.  The idle must have been in the 2000 range before the accident!  It was reading 1680 rpm when I first checked it.  

I lowered it to 1420 rpm and it sounded a bit better.  Sadly, at "full seat" on the idle screw, its still in the 1200 rpm range.  Oh well, something to research for another day.  

Update:  turns out I had the tachometer in the motorcycle mode versus the car mode, hence the high RPM reading. Once I put it into the right mode it's now idling nicely at 1000 RPM. I believe the manual says between 950 and 1000 so I think we're good for now.


RichardM said...

That is a really high idle. Are you sure it wasn't picking up two cylinders? Did it sound that high? Shifting the transmission into gear would be a real "bang" at that speed.

redlegsrides said...

You hit the nail on the head, RichardM! This morning I realized I was using the wrong mode on the tachometer. Thing Two had mentioned that the engine seemed to idle down to almost stalling while sitting still. So while checking again I realized and selected the correct mode and now the idle is at 1000 RPM.