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Small engine tachometer and hour meter for petrol tools

Updated: October 2026

Your petrol mower, generator, or chainsaw has no rev counter and no hour clock, and you want to know when the next service is due and roughly how fast the engine is running. A small engine tachometer hour meter answers both: it reads the spark pulses in the plug lead and logs running time. This page explains what these inductive meters can and cannot read, and where a chainsaw owner should stop. The five inductive listings sit alongside the handheld meters in the [main tachometer comparison](/hub/saw-accessories/tachometer). If you are not sure you need this family at all, start with the [tachometer buying guide](/hub/saw-accessories/tachometer/sub/tachometer-buying-guide).

Your petrol mower, generator, or chainsaw has no rev counter and no hour clock, and you want to know when the next service is due and roughly how fast the engine is running.

Our top picks

YOOREAL YOOREAL YR-HM011F hour tachometer

Best overall

YOOREAL YOOREAL YR-HM011F hour tachometer
7.1/10about £13.99
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NInE-ROnG NInE-ROnG RL-HM032R hour tachometer

Rank 2

NInE-ROnG NInE-ROnG RL-HM032R hour tachometer
7.3/10about £18.59
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YOOREAL YOOREAL YR-HM011J clip hour tachometer

Alternative

YOOREAL YOOREAL YR-HM011J clip hour tachometer
6.7/10about £17.89
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On this page
  1. 1.What this meter can read
  2. 2.Hours, patterns, and the cell
  3. 3.A chainsaw limit
  4. 4.Which listing fits a petrol tool

What this meter can read

An inductive tachometer wraps or clips the high-tension lead to the spark plug, counts the pulses as rpm, and adds to an hour counter while the engine runs. It only works on a spark-ignition petrol engine. A diesel has no spark plug. A battery mower or a mains motor has no ignition. Those need a handheld photo or contact meter. An inductive meter is not a laser tool, even when a listing calls it non-contact. The YOOREAL YR-HM011E, YR-HM011F, and NInE-ROnG RL-HM032R print 0–20,000 rpm. The YR-HM011J prints 0–25,000 rpm. The POFET 1672 prints up to 99,999 rpm, which sits far outside that band and reads like a display limit. Small garden engines sit well inside 20,000 rpm. Two titles name chainsaws: the YR-HM011F and the POFET.

Hours, patterns, and the cell

If the firing pattern is wrong, rpm halves or doubles while the hour counter still runs. A UK YR-HM011E buyer saw 3,000 rpm against 6,000 on the bike until the wasted-spark setting was chosen. A UK POFET buyer saw about 1,400 rpm on a mower expected near 2,900, and that listing prints no pattern setting. Counts are three on the YR-HM011E and YR-HM011F, eight on the NInE-ROnG, and nine on the YR-HM011J. The first two reset total hours. The other two do not. The YR-HM011E seals its CR2450. The YR-HM011F and the NInE-ROnG use a cell you can change. Only the NInE-ROnG prints IP65, and one UK YR-HM011F reviewer found no seal on the battery door.
YOOREAL YOOREAL YR-HM011F hour tachometer

Testsieger

YOOREAL YOOREAL YR-HM011F hour tachometer
7.1/10about £13.99
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A chainsaw limit

Tickover and maximum speed come from that saw's own manual. STIHL's MS 170 and MS 180 manual lists an idle of 2,800 rpm, to ISO 11681, with a tolerance of ±50 rpm. That figure is for those models. Another saw can idle at a different speed. If the chain still turns at idle, take the saw to a dealer. STIHL M-Tronic saws have no manual mixture screws, so the meter is only for observing. The Health and Safety Executive expects training for chainsaw work on or in a tree. Wrap counts are on the how to use a tachometer page.

Which listing fits a petrol tool

For a chainsaw named on the box, the YOOREAL YR-HM011F at £13.99 prints 10 rpm steps, three patterns, a 0.5 second refresh, and a replaceable CR2450, with 4.4 stars from 259 reviews. The battery door is unsealed. For a mower or tractor outdoors, the NInE-ROnG RL-HM032R at £18.59 has IP65, eight patterns, a CR2032, and 4.2 stars from 543 reviews. The cell can flatten within two weeks if the display stays on. The YR-HM011J at £17.89 adds nine patterns and a clip. The YR-HM011E at £11.99 has a sealed cell. The POFET names chainsaws and prints no pattern setting, so use it for hours rather than tuning. The best tachometer page sets these next to the handheld picks. If you buy through our links, we may earn a commission at no extra cost to you.

Common questions

Will an inductive tachometer work on a chainsaw?
Yes, on a petrol chainsaw with a spark plug. You fit the pickup on the plug lead, choose the right firing pattern, and the meter shows rpm and hours. Two listings in this amazon.co.uk set name chainsaws in the title: the YOOREAL YR-HM011F and the POFET 1672. Always take target speeds from your saw's own manual rather than a general figure.
Will a small engine tachometer work on a diesel or battery mower?
No. An inductive tachometer counts spark pulses in a petrol engine's plug lead. A diesel engine has no spark plug, and a battery or mains mower has no ignition, so the meter has nothing to read. For those machines, use a handheld photo or contact tachometer on a visible rotating part instead.
Why does my hour meter show half the rpm?
The firing-pattern setting probably does not match the engine. Some engines fire the plug once per revolution and others every second revolution, and a wrong setting halves or doubles the reading. Change the pattern in the menu and compare the result with a known speed until they agree. The hour counter is usually still correct.
What idle speed should I set on my chainsaw?
Use the figure in your saw's manual. STIHL lists 2,800 rpm for the MS 170 and MS 180, measured to ISO 11681 with a ±50 rpm tolerance, but that applies to those models only. If the chain still moves at idle, stop and take the saw to a dealer. Saws with STIHL M-Tronic have no manual mixture screws to adjust.
Does waterproof mean I can leave an hour meter in the rain?
Only if the listing prints an IP code. In this set, only the NInE-ROnG RL-HM032R states IP65, and UK owners report it working through rain on a garden tractor. Other listings use the word waterproof without a code, and one UK reviewer found a YOOREAL battery door had no seal. Store the machine under cover if the meter has no rating.
Is a clip better than a wire wrap on an hour meter?
A clip is quicker to fit and remove, which helps if you move the meter between engines. The YOOREAL YR-HM011J uses one on the plug. A wrapped wire, such as the four to five turns the NInE-ROnG specifies, stays put once tied and suits a meter fitted for good. Both read the same spark pulses.

Related pages

Tachometer

Best tachometer UK: two lists, not a single winner

Digital tachometer buying guide: photo or hour meter

How to use a tachometer and get one stable reading

Contact vs non-contact tachometer: which mode to use

Sources

Sources checked for this comparison; last retrieved on 16 October 2026.

  1. GOV.UK, laser radiation safety advice (retrieved 16 October 2026)
  2. HSE, lasers (retrieved 16 October 2026)
  3. HSE, work-equipment inspection (retrieved 16 October 2026)
  4. HSE, training and competence (retrieved 16 October 2026)
  5. Consumer Rights Act 2015, section 9 (retrieved 16 October 2026)
  6. Consumer Rights Act 2015, section 22 (retrieved 16 October 2026)
  7. Compact Instruments, optical tachometer manual (retrieved 16 October 2026)
  8. STIHL MS 170/180 instruction manual (retrieved 16 October 2026)