Ignition
- 122 timing is not published. 123 is 19 degrees BTDC.
- Pick-up resistance is not the same on the two engines.
- Plug gap is 0.5–0.7 mm.
RS125 · 1993–2006
Ignition
Type 122 is Nippon Denso. Type 123 is SEM. Resistances below are the aligned retake, not the earlier offset reading.
| Check | Type 122, Nippon Denso | Type 123, SEM |
|---|---|---|
| Static timing | Not published | 19° / 1.84 mm BTDC. Haynes 4298. Hartrusion prints the same static figure. |
| Check at 10,000 rpm | Not published | 12° / 0.74 mm. Hartrusion, not the Haynes extract. The 123 stator sits in slots so it can be moved. |
| Source coil | 0.1–1.0 Ω | 1.58–1.94 kΩ |
| Pick-up coil | 190–300 Ω | 170 Ω |
| Pick-up air gap | 0.5 mm | 0.5 mm |
| HT primary | 0.11–0.21 Ω | 0.5 Ω |
| HT secondary | 4.3–8.1 kΩ | 1.9–2.4 kΩ |
| Pick-up coil bolts | 5 Nm | 5 Nm in the shared engine table |
| Spark plug | NGK BR10EG, gap 0.5–0.7 mm, 20 Nm | NGK BR10EG, gap 0.5–0.7 mm, 20 Nm |
Hartrusion says the Rotax 123 has more advance from idle up to 4,000 rpm than the Rotax 122, and that newer 122 curves sit close to the curve on that page. A degree number for the 122 is stillNot published. Do not copy the 123 marks onto a 122.
An early reading had the pick-up resistances swapped and the Type 122 pick-up bolts at 2 Nm. The clean retake replaces both. Charging output and stator resistance are on theelectrics page, because the Type 123 source-coil figure above is not the stator figure.
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Sources
Research brief dated 24 October 2026. Where this page says “the brief”, that is the sourced master plan behind the first edition.