How to read a Beru spark plug reference
A Beru technical code encodes the thread & seat, resistor, heat rating, reach, electrode and material. Here is how to decode it.
A Beru technical code such as 14 FR-6 LDU3 is read left to right: the thread size, the seat / configuration letters, the heat rating after the dash, then reach, electrode and material. (Beru also prints a short catalogue code like Z194.)
1. First number — thread
| Number | Thread |
|---|---|
| 10 | M10×1.0 |
| 12 | M12×1.25 |
| 14 | M14×1.25 |
| 18 | M18×1.5 |
2. Letters — seat & configuration
- F / S / V — flat seat (with gasket)
- K — conical (taper) seat; T — small-engine taper seat
- G — surface-gap plug; GH — surface gap with auxiliary spark path
- R — built-in interference-suppression resistor (5 k/10 k)
- Z — two-stroke-engine plug; ZR — Bi-hex (double hexagon)
3. The number after the dash — heat rating
Beru's heat rating (Wärmewertkennzahl) runs on a new scale (e.g. 6, 7, 8…): a lower number is colder, a higher number hotter. It maps to an older 25–400 scale. It is relative to Beru.
4. Reach & spark position
A letter (A, B, C, D…) codes the thread length / spark position — e.g. A/B ≈ 12.7 mm reach, C/D ≈ 19 mm reach.
5. Electrode & material
- Ground electrode: T triangular, multipolar variants
- Material: U Beru ultra (NiCu), S silver, P platinum, I iridium, E nickel-AL
6. Tightening torque
Torque depends on the seat, thread diameter and cylinder-head material. Flat seat (with gasket): 10 mm 10–15 N·m (iron) / 10–12 (alu), 12 mm 15–25 / 15–20, 14 mm 25–35 / 25–30, 18 mm 35–45 / 35–40. Taper seat: 12–14 mm 10–20 N·m, 18 mm 20–30. Always follow the value printed on the box.