Handheld Tach

[Burchie70]

Anyone have a wireless handheld tach to check rpm’s of a saw that they like ? I tune it by ear now and I think I’m fairly close but just want one to check accuracy. I don’t really want to spend a lot on one but don’t want to get a cheap one that isn’t even close either. Also wondering how the wireless even work ? Thanks

 

[CausticUC]

I use an Opamma PET-1100R, but I need it for more than just chainsaws. It can be wireless or you can use the sense clamp.

Opamma is not cheap, and they are the ones that make the Stihl, Husqvarna, and Echo branded tachometer.

https://www.oppama.co.jp/tachometer-eng
Wireless in the Opamma are inductive sense. Roughly stated it senses the EMI burst.

Other "wireless" method are optical and use reflective sticker.

 

[TheTone]

I have a FastTach made by Design Technology Inc. I have trouble getting it to connect to the spark no matter how and where I hold it. This makes it nearly useless to me. The people at Design Tech are very nice and I sent mine in for testing. They said it checked out fine. They even offered to send a replacement. The only advantage I could see were: hand held rather than wired, and faster refresh rate compared to the cheaper ones. Having said that, I have had better overall results from the Ebay $10-$20 wired versions compared to the $100 FastTach.

 

[Burchie70]

Thanks for the help, I’ll have to look at them online

 

[Jeff Lary]

Following along,
I need one to set up my 5105 the cat muffler and limited coil make it hard for me to get the set up correct. Had the saw 3 years and I hate it.

 

[Okie]

I've got a 6 year old Echo, don't recall the model, works really good.
I think it is a Pet 304. Refresh rate is really fast. I've never had to replace the internal battery.
You might do a saved search on flea bay and come up with one at a reasonable price, but buy new, not used.

I made sure that I can get inside and replace the battery. Some of the expensive ones are sealed and have about a 5 year battery, even if not being used and the units are sealed up.

I rely more on a IR (infrared thermometer instead of the tach for final tuning so as to make sure the saw is not overheating in the cut due to being tuned or running lean. The IR has detected and saved several expensive saws from overheating and eventually ruining the block/piston/cylinder when into a loaded up cut due to overheating issues that a tach would not have shown. the rpms were still way below specs is what I'm saying, but the engine was running lean or had other issues when under a full load in the cut. Most generally the engine was running lean when into a long heavy cut (long is 1 minute or more) instead of clogged cooling fins or air flow around the block.

Saw would run a long time without any detectable issues if just trimming or making cuts where on-off the throttle but full bar cuts would bring out the overheating issue.

 

[CausticUC]

If I recall correctly the Echo is the PET-304 or the older PET-2000 from Opamma. Occassionally they will come up at a reasonable price, and if you only have single cylinder engines they are a good option.

 

[furb]

I have a pet304 that’s been around for a few years and works well

 

[TheTone]

I rely more on a IR (infrared thermometer instead of the tach for final tuning so as to make sure the saw is not overheating in the cut due to being tuned or running lean. The IR has detected and saved several expensive saws from overheating and eventually ruining the block/piston/cylinder when into a loaded up cut due to overheating issues that a tach would not have shown. the rpms were still way below specs is what I'm saying, but the engine was running lean or had other issues when under a full load in the cut. Most generally the engine was running lean when into a long heavy cut (long is 1 minute or more) instead of clogged cooling fins or air flow around the block.

Okie, what temperature range do you aim for? What is your upper limit for safety? Do you aim the IR at the center of the cylinder between the fins?

 

[Okie]

IR temp of chainsaws using a IR therometer

Nominal OK temp max 350F if reached slow in in a full bar cut.

If the temp is rising fast and gets to 375 headed for 400 take it out of the cut and let the engine cool down to 350 or less before killing the saw. Do not kill it when hot or it may continue overheating and may even seize after killing the engine. Will cool off faster out of the cut with the engine running using flywheel air..

Try to aim the therometer at the piston jug. Not critical where it's aimed just watch and make sure it's not headed for 375 fast if it goes fast it will overrun and get to 400 before it starts to cool down. A fast temp climb is a indicator of a fast overheat most generally caused by too much air into the crankcase. (not enough gas)
If the temp is rising slowly it most generally will peak at around 325.
You can do this by yourself with a sharp chain using one hand to run the saw and the other to aim and watch the Infrared therometer. With a sharp chain the saw will dig in and load up by itself.
You need to prepare for a 1 min or longer run so as you can see what the max temp is when it's reached. I've seen saws that won't even overheat and seize when taking short cuts jogging the throttle on-off, but load thre saw in a long load cut and it's starts overheating and eventually will just start bogging down, the operator thinking it's just chip bogging or flooding but what is actually happening is the piston is heating and swelling into the cylinder and chewing metal and it goes into a self destruct fast. Sometimes the engine will seize, pull rope hard to pull or not pull at all and the saw may start and run if left to cool off. (but it's headed for self destruct again if the issue of overheating is not corrected. The oOP may not even notice the problem again until he gets the saw loaded up heavy again in a long engine loaded cut.
I've replied to quite a few Tach threads on here about using the IR temp to make sure a saw is not running lean or getting too hot when loaded up in a long cut. A tach will still show the rpm's within spec because the engine is loaded down. Most generally the overheating is caused by not enough gasoline hitting the piston, (running lean) which is what keeps the piston
cooled and why is usually the best to tune the carb for a rich condition on a chainsaw.
IR therometers can be had very reasonably priced now days

 

[Okie]

Using IR therometer to test a chainsaw block for overheating when doing full bar cuts on a big log.
I happen to live in rural country with big pine trees readily available just outside the door and I keep a big white pine log on the ground within 50 yards of the shop to use for testing chainsaws after repairs. I do not have to load up the saw and drive to the back woods for a test.
Also the price of Pine timber is also almost worthless now days in my neck of the woods as compared to 25 years ago. Wife uses the chips for mulch around some plants and Blue Berry bushes.
Also shortage of toilet paper in this area. Them pine cones and pine limbs are not user friendly for toilet paper especially if they have rosin on them.

 

[lone wolf]

Using IR therometer to test a chainsaw block for overheating when doing full bar cuts on a big log.
I happen to live in rural country with big pine trees readily available just outside the door and I keep a big white pine log on the ground within 50 yards of the shop to use for testing chainsaws after repairs. I do not have to load up the saw and drive to the back woods for a test.
Also the price of Pine timber is also almost worthless now days in my neck of the woods as compared to 25 years ago. Wife uses the chips for mulch around some plants and Blue Berry bushes.

What is you operating temp and when do you shut down?

 

[pioneerguy600]

What is you operating temp and when do you shut down?

Post # 10 up a couple ^

 

[Okie]

First just use the IR thermometer on couple of chainsaws in a full bar cut that you think are normal and not giving any issues so as to become familiar with what to expect.

Then when you see the IR temp block/jug going up fast and starting to exceed 350 and headed for 400 area you will know to back off the load cut and try to make corrections BEFORE the pistons skirt starts swelling into the jug.
Also if you see a chainsaw that still runs but has a scored piston and you are thinking about rebuilding/replacing the jug and or piston I would do a IR temp test before I tore the block apart so as too see if it's STILL overheating due to leaning out or maybe someone straight gassed or maybe it was a chunk of carbon and not running lean. I've seen saws with a severely scored piston and jug run a long time with no overheating after correcting a lean condition due to carb being adjusted wrong. I've also seen saws that would severely overheat and even seize up in a full bar long cut but not give any SIGNS of overheating issues if only doing light trimming cuts.

 

[dsell]

I have the Electronic Specialties 328 EZ Tach Plus. It's reliable, but the update rate is slower than I like.

 

[Okie]

On subject of Tachs, overheating, and tuning so a to not overheat IN THE CUT.
I saw this one in a post on here and I copied/Paste to here.

-Aaron
Tune old saws in the wood.
Adjust the H side so that it burbles (four strokes) at WOT unloaded, and runs clean when under load in the cut. When you lift cutting pressure, it should immediately revert to four stroking. Warm up the saw before tuning it.

-John 3:16-

 

[CausticUC]

As there seems to an emphasis on temperature and when to take it, this is equally true for when you measure/set RPM.

Many times convenience is one's own worst enemy whether you use one method or both. Having an engine on the bench where everything is handy and out of the way usually means that many people will do an initial setting and think "I'll check under/after a hot load later, this is good enough for now".

This is true for many people (maintenance or rebuild), not all, there are some that have the helpers or discipline to do it right.

Back to tachs; what is true for IR temperature measurements is true for properly reading/setting rpm limits. You get different results cold, warm, hot, hot after load, post brake-in, elevation, etc.

Both methods require you to measure at elevation, post break-in, during and after load. The reason being is thermal runaway, which also shows up on the tach as excessive rpm that does not manifest at cooler temperatures. Depending on tool resolution you will notice this if it is in range of your tool.

That said, a high resolution IR thermometer is much cheaper than a high resolution tachometer (some cheap tachs are as bad as +/- 1000 rpm; that means it could be as much as 2000 rpm out!) but both are very useful tools.