The Yellow Square unit is a digital tachometer and hour meter for 2-stroke and 4-stroke petrol engines. It reads up to 99 999 RPM, logs up to 10 000 engine hours, has a service timer, connects inductively to the spark plug lead and runs on a built-in battery. IP68 housing, -30 to +85 °C.
Specifications
| Parameter | Value |
|---|---|
| Functions | tachometer, hour meter, service timer |
| Engine type | 2-stroke and 4-stroke petrol |
| Maximum speed | 99 999 RPM |
| Hour meter | up to 10 000 engine hours |
| Operating principle | inductive, 5–6 turns around the spark plug HT lead |
| Power | built-in battery |
| Battery life | over 20 000 hours |
| Protection | IP68 (dust and water protected) |
| Operating temperature | -30 to +85 °C |
| Display | black-and-white LCD, 12 × 41 mm |
| Backlight | yes |
| Lead length | 2 m |
| Dimensions | 73 × 47 × 20 mm |
| Mounting | panel or frame, cable ties or self-tapping screws |
| Installation time | about 15 minutes |
What you get
- Three instruments in one — tachometer, hour meter and service timer.
- No wiring surgery — the signal comes from 5–6 turns around the plug lead.
- Automatic modes — RPM while running, total hours after shutdown.
- Water and dust protected — IP68 housing.
- All-season use — -30 to +85 °C.
- No battery swaps — built-in battery rated for over 20 000 hours.
- Quick fitting — about 15 minutes with ties or screws.
Who it is for
Owners of outboard motors and jet skis, scooters, mopeds, motorcycles and quad bikes, garden machinery, petrol generators and water pumps who want to see engine speed and track hours for timely servicing.
Who it is not for
Owners of diesel or electric machines: the unit reads the spark plug HT lead, and the stated compatibility covers 2-stroke and 4-stroke petrol engines only.
Uses and compatibility
Compatibility: 2-stroke and 4-stroke petrol engines. Uses: watercraft (outboard motors, jet skis), motorbikes (scooters, mopeds, motorcycles, quad bikes), garden machinery (lawn mowers, chainsaws, trimmers, cultivators), power equipment (petrol generators, water pumps), and hour logging for oil changes and service reminders.
In the box
Digital tachometer with built-in power cell, 2 m connecting lead, user manual.
Questions and answers
How do I connect it?
Wrap 5–6 turns of the lead around the spark plug HT wire and fix the housing to a panel or frame with cable ties or screws. Installation takes about 15 minutes.
Do I need to replace a battery?
It runs on a built-in battery rated for over 20 000 hours.
How does it switch modes?
Automatically: RPM appears when the engine starts, and total running time shows after it stops.
Can it handle water and mud?
Yes, the housing is IP68 rated and works from -30 to +85 °C.






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