1971-1973 Arctic Cat Snowmobiles Factory Service Manual, Page 71Get this manual
ENGINE SERVICING (WANKEL KM914B) Then slowly vary the setting of the adjusting screw of the idling jet so that the engine speed increases smoothly when the throttle is openedThe main jet is correctly adjusted when the engine gives satisfactory two-stroke operation under load and only slight fumes are discharged from the exhaustIf there is excessive exhaust smoke under load, turn main jet adjusting screw clockwise (closing) until smoking stops and engine runs satisfactorilyIf the idling speed fluctuates too much or is too high, turn the idling jet adjusting screw anti-clockwise (to open the jet) until the engine runs smoothly at lower speed without beginning to discharge more smoke from the exhaust
PRESERVING THE ENGINE