Polini Thor 250
It is a good idea to check Polini's website to get the latest (or additional) information.
Carburetor PWK 28 – main jet 118 (according to Polini but it could be something else). Bruce Stenulson has some important notes on how this carburetor fails suddenly and a fix. Pilots might want to consider the Bing as a replacement.
Note: Polini updates their parts frequently so these lists may not be 100% accurate.
Dual spark plug wiring diagram – the dual system employs a magneto and a CDI. The CDI provides a more powerful spark and increases the efficiency and power of the engine. The magneto circuit is the same as the Thor 130. The resistance of the magneto is about 290 Ohms.
Spark plug – Champion RN2C gap 0.023"-0.028" (0.58mm - 0.71mm) Polini does not specify the gap value (!) in their engine manual. The value here is from Champion's technical site. Because of the engine's powerful ignition, the larger gap may be used. If there are any issues with missing at full load, decrease the gap.
Specifications & torque values – see "User manual" below
User manual (single and dual spark plug)