Two-stroke engine control

A power tool comprising:

• a cutting disc associated with an inertia;
• and
• a two-stroke combustion engine arranged to power the cutting disc, the two-stroke combustion engine comprising a user-operated throttle control, an adjustable valve arranged to control an air intake of the combustion engine, and a control unit arranged to control a state of the adjustable valve,
• wherein the power tool is arranged to use an inertia of the cutting disc as energy storage, whereby the energy storage allows a time limited cutting operation without combustion engine drive of the cutting disc, thereby allowing control of the adjustable valve in response to variations in combustion engine speed or load.

A two-stroke combustion engine for use with a tool associated with an inertia, the combustion engine comprising:

• a user-operated throttle control;
• an adjustable valve arranged to control one or more air intakes of the combustion engine;
• and
• a control unit arranged to control a state of the adjustable valve,
• wherein the combustion engine is arranged to operate in a first idle mode at an idle engine speed below a clutch engagement engine speed when the user-operated throttle control is not engaged,
• wherein the combustion engine is arranged to operate in a second idle mode at a target engine speed above the clutch engagement engine speed when the user-operated throttle control is engaged and when the engine is not subject to an external load, and
• wherein the control unit is arranged to control the state of the adjustable valve to maintain engine speed at the target engine speed when the engine operates in the second idle mode.