Tachometer for Lawnmower and Chainsaw Servicing

GregMonarch on 24/09/2019 - 18:18

Whirlpool has become useless. I posted this over there but the anal mods have gone crazy, deleting sensible posts requesting others' experience/opinion/advice - instead directing you to a canned response basically saying: "Use a search engine." Fools!

Anyway…

I can only seem to find cheap/nasty Chinese tachometers. Which would be fine as long as they're accurate. But I just watched a youtube video where there was 300 rpm difference between two different types. Not a big deal for a lawnmower, but apparently if you lean-out the fuel mixture of a high-revving chainsaw, thinking your rpm is 300 lower than it actually is, you can cook the engine.

I was thinking about a laser type. But most of them have no description of usage, except one that said it requires a reflective strip placed on the rotating engine/shaft. Which kind of defeats the purpose of 'point and shoot'. So I think I'll get the inductive type.

  • Does anyone have experience/have one?
  • What is a decent (as-in accurate - not necessarily a few hundred $) brand?
  • Or to put it another way, where do mower repair places source such tools (rather than the $10 stuff on Aliexpress)?
Automotive

Comments

  • brendanm on 24/09/2019 - 19:34

    https://www.tinytach.com/

    Yes the phototachs need a bit of reflective tape to work.

    • GregMonarch on 24/09/2019 - 21:58
      -1

      Thanks.

      That might do. But it seems they have an internal battery that can't be replaced.

      • brendanm on 24/09/2019 - 22:07

        Should last for a fair while. Lots of jet ski and outboard guys use them, pretty sure the motorbike crowd do as well, known to be pretty accurate. Website says 5+ years on the battery, ends up pretty cheap overall compared to buying a crappy Chinese one every year, as well as knowing it's good.

        • GregMonarch on 24/09/2019 - 22:26

          Oh, hang on - they make the other one I mentioned below too.

  • hawkeye on 24/09/2019 - 19:37
    -1

    You know these things have an accelerator controller so if you think it's going to pop back off and reduce the load. The load strain is going to do the damage. If you can't hear or feel it no money in the world will compensate for common sense sensor your asking for.

    • brendanm on 24/09/2019 - 19:41

      What? He wants to find what max rpm it's hitting so it can be tuned to the spec in the service manual.

  • jpl on 24/09/2019 - 19:38

    For continuous monitoring I have this on my outboard and perform flawlessly. It got sold with the outboard after 3 years of use. It can be programmed to do 2 stroke or 4 stroke.

    Tinytech @brendanm posted is a better brand than the one I use.

    • GregMonarch on 24/09/2019 - 22:20
      -1

      Thanks. Yep, there's several like this on Aliexpress. These are the type I saw the video of, where the guy compared it with another he had and there was a difference of about 300 rpm between them. I put that together with another video I saw, where a guy adjusting the carby on his chainsaw said something like a difference of just 300 rpm can cook the head if you set it to run too lean and your tacho is inaccurate. I didn't pay a lot of attention to what he said because I don't own a chainsaw yet. But I will one day, so I may as well buy something better once.

      I'm comparing these three atm:

      Electronic Specialties 328 EZ Tach Plus
      https://www.amazon.com/dp/B002Z32OHW
      This can be both wireless or wired. Sample rate is a bit slow, but I guess that doesn't matter (just need to hold the throttle steady for longer).

      DTI TECH-TACH TT-20K Tachometer
      https://www.tinytach.com/pdf/TT-20K-tachometer-operating-ins…
      This seems to be popular.

      General Technologies Corp GTC TA100 Smartach+ Wireless Ignition Analyzer and Tachometer
      https://www.amazon.com/dp/B000RT9BH2
      No idea if this is any good. I'd guess so though, going by the price.

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