Husqvarna's model 40 chainsaw is designed as a mid-range saw for light and occasional homeowner cutting needs. This saw is smaller and lighter than a professional felling saw but bigger and stronger than an electric chainsaw. The specifications for this chainsaw have been set at Husqvarna to achieve the maximum performance. You should use these specifications during repair and maintenance to ensure the highest level of performance.
The Engine on the 40
The model 40 chainsaw has one piston, which moves up and down inside the cylinder. This piston is 40 centimeters cubed or 2.43 cubic inches. When the piston moves up and down, it uses a stroke of 32 mm or 1.26 inches. This piston moves inside the cylinder bore, which for the model 40 is of 40 mm or 1.57 inches. When the 40 reaches an operating speed of 9,000 rpm's, the engine creates about 2 kW of power. The maximum speed for this engine, without a full load, is around 12,500 rpm's, which you should never adjust the high speed carburetor screw to go above. The idle speed on the 40 is 2,500 rpm's. The clutch uses enough centrifugal force to push the clutch shoes and clutch springs outward to engage the clutch drum and sprocket.
The Ignition System
The R.E. Phelon Company manufactures the 40's ignition system. The spark plug used in the 40's ignition system is a Champion RCJ 7Y. This spark plug will need an electrode gap of .02 inches or .5 mm. The ignition module has two wires that lead out of it: the lead wire and the short-circuit ground wire.
The Fuel and Lubrication System
The carburetion system on the 40 chainsaw is a Zama C1Q, which utilizes a butterfly valve. On the end of the carburetor, an integrated fuel pump sucks fuel up from the tank and into the carburetor via a diaphragm that pulses with the crankcase. The fuel tank's maximum capacity is 1.06 pt. or .5 L. The mix fuel used on this engine should only be a 90-octane or above regular unleaded fuel mixed with air-cooled two-cycle engine oil. The mix ratio for the fuel should range from 25:1 to 33:1. You should never use automotive oil as the oil for mixing; outboard two-cycle or four-cycle oil will also damage the fuel system if used. The oil tank's capacity is .53 pt. or .25 L. The 40 also uses an automatic oiling system with an adjustable screw that allows you to control the flow of bar oil.
Bar and Chain Specifications
The standard bar size that comes from the factory is 13 inches or 33 cm. The 40 can also run with a 14,16 and 18-inch bar. The usable cutting length for these bar lengths ranges from 12.6 to 17.5 inches. The maximum chain speed at full power will be 17.4 meters per second. The pitch for the chain is recommended to be .325 inches that has a drive link of .05 inches thick. The drive sprocket on the 40 uses seven teeth.