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I do my own lawn equipment motor repairs myself. So lately I have been thinking and it would be good for me to have a good means to check the rpms on some of this equipment. I know I can buy an Ebay or amazon tach that you wrap the pickup around the plug wire but not sure if this is the correct way to go. So, question is what do you real world repair people use? If you all feel that the inexpensive ones are good enough than I would go that way, they just seem to be hokey. Because of having 2 and 4 cycle plus single to twin cylinders the inexpensive ones you have to keep changing the info to get the proper rpm readings. I don't think I would need to spend $300.00 to get something that would work for my use. Thanks Maybe I am just over thinking this.

I've used this type for the last 40 years and servers me well...




Opinions will vary but I feel its about as accurate it gets. And works on any running motor and any given rpm...
Look around as I'm sure it can be bought cheaper.

No you don't have to be constantly changing the settings.

99% or better of small engines uses magnetos with wasted spark. Otherwords the plugs spark every revolution. 1 spark per RPM; be it two cycle or four cycle. Doesn't matter if they one plug or two plugs so inductive tachs are set to to one spark per rev. It only when you start getting into engines that use distributors when you start needing a different setup for measuring rpms. Even then it is usually one per two revs when it is a four cycle engine but that can be different depending where you are taching off the distributor which operates off the camshaft.

It like the old JD 420 here if tach off one of the plugs then use one setting but if you are tach off the coil lead then you use a different setting. When you do coil lead it fires the number cylinders per rev of the distributor. Otherwords the cylinder engine would be reading double on meter than the actual rpm or vica vesa. I never really got into that area with any of my tachs here.

As in shop RPM checks I have use Tiny Tach inductive meters but currently I using a Husqvarna/Echo tach to these tests. Note that I rarely check the rpm on anything other small engines.

Now if you plan to leave the tach on the engine then wrapping the pickup lead to one of the plugs is best.

I’ve also have used the VibraTach pictured since the 70’s. Once you learn how to use it, it is extremely accurate, but must advise there is a learning curve.

Do I do not want to leave any one of the options on the units I plane to use it on different motors at different times as needed. Thanks, for the replies and I still am debating on the options people have been using.

I Bought a TinyTac inductive unit as well
The shop came with an Inductive dial tach, I use that a lot as well but it is big & clunky where as the TT sits in my pocket .
The dial display is good for things that fluctuate a bit like a chain saw that dose 12,000 rpm, hard to get a handle on that with a digital tach
I also have a reflective tape laser tach I use for lathe work because the original speed decal had worn off the small one & a change or motor on the big one caused it's plate to be wrong but at $ 500 ( aus) a bit expensive for mower work .

The one that I use from Husqvarna seems to do a good job @ 12K. My Tiny Tach II did a fairly good job at 12K too, just the battery failed as it on all the time instead of stand by like the Husqvarna tach.

It depends on what you want to measure?
I got a mechanical/photo tachometer. Then I don't need to have any ignition or electrical connections and I can do stuff like PTO/shaft rpm's or electric motor speeds. I have some stuff that it's very difficult to get to anything so access is a major problem. Interestingly it also can measure surface speed for say a sanding belt. The photo part can read to 100K rpms and the mechanical section can read to 20K rpms.

I have an Extech Model 461895. Way too expensive new at around $266! BUT I shopped used on EBay and they are much cheaper. Usually you can find one under a $100.


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clubairth said:

It depends on what you want to measure?
I got a mechanical/photo tachometer. Then I don't need to have any ignition or electrical connections and I can do stuff like PTO/shaft rpm's or electric motor speeds. I have some stuff that it's very difficult to get to anything so access is a major problem. Interestingly it also can measure surface speed for say a sanding belt. The photo part can read to 100K rpms and the mechanical section can read to 20K rpms.

I have an Extech Model 461895. Way too expensive new at around $266! BUT I shopped used on EBay and they are much cheaper. Usually you can find one under a $100.

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I have an old photoelectric tach from days past that I used on model airplanes. Never sold it or threw it out, it comes in handy for measuring engine speed at the flywheel as long as I mark it properly...

I also use the vibertach. Never had any problems.

So, Thanks for all the replies and I went with an inexpensive Tach/Hour meter from Ebay. I didn't want to go super nuts so thought this would be OK for what I needed it for and the use I will be giving it. The only thing is you are supposed to wrap the pickup 5 times around the plug wire to get a reading. I seen on you tube ware a fellow added a clamp instead to the wire and seemed to work without all the wrapping and he did show a sample with two units one clamped and the other wrapped and they both showed the same so hoping this may work for me as well. I have the unit and put on the clamp but a bit to cold out to go to the shed and try it out but will later this week when it gets up to 40. Thanks, again for taking the time to reply.

I used a tie-wrap to hold the pickup wire on the spark plug lead. It works well.

Got a little warmer so tried out the Tach/Hour meter, Like I said I seen the hack on YouTube about the small clamp instead of wrapping the wire and it works just fine, now all I do is clamp on the plug wire and it's good to go. I had the clamp from some other fix it job so was just a time thing, and you don't do anything but loop the wire thru the clamp and your done don't need to solder or anything just bend the clamps retainers to hold the wire on.

OldDiyer said:

I do my own lawn equipment motor repairs myself. So lately I have been thinking and it would be good for me to have a good means to check the rpms on some of this equipment. I know I can buy an Ebay or amazon tach that you wrap the pickup around the plug wire but not sure if this is the correct way to go. So, question is what do you real world repair people use? If you all feel that the inexpensive ones are good enough than I would go that way, they just seem to be hokey. Because of having 2 and 4 cycle plus single to twin cylinders the inexpensive ones you have to keep changing the info to get the proper rpm readings. I don't think I would need to spend $300.00 to get something that would work for my use. Thanks Maybe I am just over thinking this.

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Thing which bothered me is that the commonly used Echo shop tach, or its clones, do not have a replaceable battery. You can't always place one of those vibration disks on the crank, nor can you always put a shiny piece of tape on it to use one of those types. You can however almost always get to the plug wire, and replace the battery on a cheap 9 dollar ebay inductive wire types.

OldDiyer said:

I do my own lawn equipment motor repairs myself. So lately I have been thinking and it would be good for me to have a good means to check the rpms on some of this equipment. I know I can buy an Ebay or amazon tach that you wrap the pickup around the plug wire but not sure if this is the correct way to go. So, question is what do you real world repair people use? If you all feel that the inexpensive ones are good enough than I would go that way, they just seem to be hokey. Because of having 2 and 4 cycle plus single to twin cylinders the inexpensive ones you have to keep changing the info to get the proper rpm readings. I don't think I would need to spend $300.00 to get something that would work for my use. Thanks Maybe I am just over thinking this.

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I uses this one. It seems to be accurate. You need access to a rotating part to affix a piece of tape or paint stripe to. It also works on anything rotating, like a lathe or ventilation fan,

I use Standix Model 1082, just hold spring against wire & good to go! Don't foget rod adjusting tool.

A VibraTach is not placed on the crank, but can be placed anywhere on the engine.

I have an app for that. It is $9 on iPhone and $7 on Android. It listens to the sound of the engine and calculates and displays the RPM from that sound. The app is called "Engine RPM" in both stores, by Real-Time Specialties (that's me). I should warn you though that it has limitations. The sound must be clear without too much noise. For example, a lawn mower with a belt-driven blade may create sound comparable to the engine, but at a different RPM. Also, the app requires you to specify a narrow range in which you expect the RPM (+/- 30%) for reliable result. Otherwise it might register twice the true RPM or half the true RPM. I mention all these limitations because I don't want any negative reviews from people who bought the app thinking it would be a drop-in replacement for a hard-wired tach. It isn't.

I installed one of these cheapos on my Exmark last year while resetting my TPS. I had to have a tach. And once I told it I had a twin cylinder four stroke, it was dead on. Can't argue with the price, as I can just leave it installed. I would bet those other tools are more accurate, but for my purposes, this worked fine.

I've got the same one Steves has. 12 years, zero issues. I use it mainly on generators, but it comes in handy for lawn equipment if the RPM sounds a bit low. Those I can usually tune by ear.

OldDiyer said:

I do my own lawn equipment motor repairs myself. So lately I have been thinking and it would be good for me to have a good means to check the rpms on some of this equipment. I know I can buy an Ebay or amazon tach that you wrap the pickup around the plug wire but not sure if this is the correct way to go. So, question is what do you real world repair people use? If you all feel that the inexpensive ones are good enough than I would go that way, they just seem to be hokey. Because of having 2 and 4 cycle plus single to twin cylinders the inexpensive ones you have to keep changing the info to get the proper rpm readings. I don't think I would need to spend $300.00 to get something that would work for my use. Thanks Maybe I am just over thinking this.

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Been using one for years because adjusting RPM by ear is about as accurate and tightening a bolt to torque value by feel. Go for it.

A SKILLED technician can get RPMS and TORGUE pretty close using the ears and touch. That said when you are charging for your services you want to use the appropriate tools to get even closer. We don’t want it coming back because we were only close. As I always told my students, “Never time to do it right, but always time to do it over”.

The vibra-tach works fine but is more inconvenient than the cheap digital ones available on eBay and amazon. I can find a picture but don't have one currently. It's a little small black plastic box with a gray window with two buttons on the front. It's about an inch and a half by an inch and a half by half inch thick and has a long wire pigtail coming off of it. That's what you wrap around the plug wire but you don't have to do that at all. I just leave the thing wrapped up in the rubber band like it comes from the factory and if you simply hold the top part on the opposite end of the wire right against your plug wire or plug tip anywhere it will pick up and show you the reading.

y use one like this one you can cut the induction wire and just put the body of the tool near spark wire and get an accurate reading
without lose time to roll induction wire you ajust it to one cylindre for all smal motors witout distributor you also test rpm on multicoils engine for cars and trucks

Heres a few photos of what the Tach/Hour meter looks like now that it is done. I also added the clamp so that I could just clamp it onto something.

After trying several kinds, I found the optical tachs to be the easiest to use. You can use it to check the RPM of anything turning. Which means it works just as well on my diesel as it does on my gas engines. I can check the speed of PTO, attachments, electric motors, etc.

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