Polini Thor 250

Please see the Thor models section for info (and warnings) that is not found here.  The Top 80 section also has info on tune up and troubleshooting issues.

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.

Cooling system 1

Cooling system 2


Note: Polini updates their parts frequently so these lists may not be 100% accurate.

Dual spark plug parts

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.

Electric starter parts

Engine parts single spark plug

Engine parts dual spark plug

Frame mounting parts

Fuel system parts

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

Thermostat parts

User manual (single and dual spark plug)

Wiring diagram