Husqvarna 3120 XP Owners Manual - Page 29
MAINTENANCE, Carburetor - rpm
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MAINTENANCE Carburetor Your Husqvarna product has been designed and manufactured to specifications that reduce harmful emissions. After your unit has been run 8-10 tanks of fuel the engine has broken in. To ensure that your unit is at peak performance and producing the least amount of harmful emissions after break in, have your authorized servicing dealer, who has a revolution counter at his disposal, to adjust your carburetor for optimum operating conditions. Functioning, Basic setting, Final setting ! WARNING! Do not start the saw without the bar, chain and clutch cover (chain brake) assembled. If you do, the clutch might come loose and cause severe injuries. Conditions • Before any adjustments are made the air filter should be clean and the cylinder cowling fitted. Adjusting the carburetor while a dirty air filter is in use will result in a leaner mixture when the filter is finally cleaned. This can give rise to serious engine damage. • Turn the low speed needle clockwise until it bottoms. Now turn it one turn anti-clockwise. The carburetor is set to L = 1. • Do not attempt to adjust the needles beyond the stops as damage can occur. • Now start the saw according to the starting instructions and run it warm for 10 minutes. NOTE! If the chain rotates the T screw should be turned anti-clockwise until the chain stops. • Place the saw on a flat surface so that the bar points away from you and so that the bar and chain do not come into contact with the surface or other objects. Operation • The carburetor governs the engine speed via the throttle. Air/ fuel are mixed in the carburetor. The air/fuel mixture is adjustable. To take advantage of the saw's maximum output the setting must be correct. • Adjusting the carburetor means the engine is adapted to local operating conditions, e.g. climate, altitude, petrol and the type of 2-stroke oil used. • The carburetor is equipped with two adjustment possibilities: L = Low speed needle T = Idling speed adjuster screw (The max. speed is controlled by a fixed needle/ electronic speed governor). • The fuel quantity required in relation to the air flow permitted by the throttle opening is adjusted using the low speed needle. Turning the needle clockwise gives a leaner fuel mixture (less fuel) and turning it anti-clockwise gives a richer fuel mixture (more fuel). A leaner mixture gives high revs while a richer mixture give less revs. • The T screw regulates the idling speed. If the screw T is turned clockwise this gives a higher idling speed; anticlockwise a lower idling speed. Basic setting and running in The carburetor is set to its basic setting when test run at the factory. The basic setting is richer than the optimal setting and should be kept during the machine's first working hours. Thereafter the carburetor should be finely adjusted. Fine adjustment should be carried out by a skilled technician. NOTE! If the chain rotates while idling the T screw should be adjusted counter-clockwise until it stops. Recommended idling speed: 2 500 rpm. ! Contact your servicing dealer, if the idle speed setting cannot be adjusted so that the chain stops. Do not use the saw until it has been properly adjusted or repaired. Fine adjustment • When the saw has been "run-in" the carburetor should be finely adjusted. The fine adjustment should be carried out by qualified person. The L-needle is adjusted first, then the idling screw T. Low speed needle L Try to find the highest idling speed, turning the low speed needle L clockwise respectively counter-clockwise. When the highest speed has been found, turn the low speed needle L 1/4 turn counter-clockwise. NOTE! If the chain rotates in the idling position, turn the idling speed screw counter-clockwise until the chain stops. Final setting of the idling speed T Adjust the idling speed with the screw T. If it is necessary to readjust, first turn the idle speed adjusting screw T clockwise, until the chain starts to rotate. Then turn, counter-clockwise until the chain stops. A correctly adjusted idle speed setting occurs when the engine runs smoothly in every position. It should also be good margin to the rpm when the chain starts to rotate. ! Contact your servicing dealer, if the idle speed setting cannot be adjusted so that the chain stops. Do not use the saw until it has been properly adjusted or repaired. High speed jet H This saw is equipped with a carburetor that has an integrated, fixed high speed jet. NOTE! There is an integrated speed governor in the ignition that limits the maximum speed 12 000 rpm. Therefore adjusting the jet does not affect the maxi- H mum speed. The high speed jet affects the saw's power. WARNING Setting the high speed jet to lean reduces the engine's power and causes overheating. This results in engine damage. Correctly adjusted carburetor A correctly adjusted carburetor means that the saw accelerates without hesitation and the saw 4-cycles a little at max speed. Furthermore, the chain must not rotate at idling. A too lean adjusted low speed needle L may cause starting difficulties and bad acceleration. A too lean setting on the H jet gives the saw lower power = "less strength", bad acceleration and/or engine damage. A too rich setting on the L-needle results acceleration problems or a too low working speed. English - 29