Husqvarna 340 EPA II, 345 EPA II, 350 EPAI manual Maintenance, Carburetor

MAINTENANCE

Carburetor				Conditions
Your Husqvarna product has been designed and manufactured				•	Before any adjustments are made the air filter should be
					clean and the cylinder coer fitted. Adjusting the carburetor
to specifications that reduce harmful emissions.
					while a dirty air filter is in use will result in a leaner mixture
After your unit has been run 8-10 tanks of fuel the engine has
					when the filter is finally cleaned. This can give rise to serious
broken in. To ensure that your unit is at peak performance and
					engine damage.
producing the least amount of harmful emissions after break in,
				•	Carefully turn the L needle to the mid point and H needle
have your authorized servicing dealer, who has a revolution
					counter-clockwise against the stop.
counter at his disposal, to adjust your carburetor for optimum
				•	Do not attempt to adjust the needles beyond the stops as
operating conditions.
					damage can occur.
Functioning, Basic setting, Final setting				•	Now start the saw according to the starting instructions and
					run it warm for 10 minutes.
	WARNING! Do not start the saw without the				NOTE! If the chain rotates the T screw should be turned
					counter-clockwise until the chain stops.
	bar, chain and clutch cover (chain brake)
				•	Place the saw on a flat surface so that the bar points away
	! assembled. If you do, the clutch might come
					from you and so that the bar and chain do not come into
	loose and cause severe injuries.				contact with the surface or other objects.
Operation				Low speed needle L
•	The carburetor governs the engine speed via the throttle. Air/			Turn the low speed needle L clockwise until the stop. If the engine
	fuel are mixed in the carburetor. The air/fuel mixture is			has bad acceleration or erratic idling, turn the L needle counter-
	adjustable. To take advantage of the engine’s optimal output			clockwise until good idling and acceleration.
	the setting must be correct.			NOTE! If the chain rotates in the idling position, turn the idling
•	The setting of the carburetor means that the engine is			speed screw T counter-clockwise until the chain stops.
	adapted to local conditions, for example, the climate, altitude,			Final setting of the idling speed T
	fuel and the type of 2-stroke oil.
•	The carburetor has three			Adjust the idling speed with the screw T. If it is necessary to re-
		L	H
				adjust, first turn the idle speed adjusting screw T clockwise, until
	adjustment possibilities:			the chain starts to rotate. Then turn, counter-clockwise until the
	L = Low speed jet.			chain stops. A correctly adjusted idle speed setting occurs
				when the engine runs smoothly in every position. It should also
	H = High speed jet.			be good margin to the rpm when the chain starts to rotate.
	T = Adjustment screw for
	idling.				Contact your servicing dealer, if the idle speed
					setting cannot be adjusted so that the chain
		T			stops. Do not use the saw until it has been
					! properly adjusted or repaired.
				High speed needle H
•	The fuel quantity required in relation to the air flow, provided
	by opening the throttle, is adjusted by the L and H-jets. If they			The high speed needle H
	are screwed clockwise the air/fuel ratio becomes leaner (less			influences the power of the
	fuel) and if they are turned counter-clockwise the ratio			saw. A too lean adjusted high
	becomes richer (more fuel). A leaner mixture gives a higher			speed needle H (high speed
	engine speed and a richer mixture give a lower engine speed.			needle H turned too much
•	The T screw regulates the idling speed. If the screw T is			clockwise) gives overrevs and
	turned clockwise this gives a higher idling speed; counter-			damages the engine. Do not
	clockwise a lower idling speed.			allow the engine to run at full
Basic setting and running in				speed for more than 10
				seconds. Turn the high speed
The carburetor is set to its basic setting when test run at the				needle H counter-clockwise
				until the stop. If the engine		H
factory. The basic setting should be kept during the machine‘s
				runs roughly, turn the high
first working hours. Thereafter the carburetor should be finely
				speed needle slowly the
adjusted. Fine adjustment should be carried out by a skilled
				minimum amount clockwise
technician.
				until the engine runs smoothly.
NOTE! If the chain rotates while idling the T screw should be				The high speed needle H is correctly set when the saw ”4-
				cycles” a little. If the saw ”whistles” the setting is too lean. If
adjusted counter-clockwise until it stops.
				there is too much exhaust gas at the same time as the saw ”4-
Recommended idling speed: 2 700 rpm.
				cycles” much, the setting is too rich. Turn the high speed needle
	Contact your servicing dealer, if the idle speed			H until the setting sounds correct. NOTE! For optimum setting
				of the carburetor, contact a qualified servicing dealer who
	setting cannot be adjusted so that the chain			has a revolution counter at his disposal.
	! stops. Do not use the saw until it has been
	properly adjusted or repaired.			Correctly adjusted carburetor
				A correctly adjusted carburetor means that the saw accelerates
Fine adjustment				without hesitation and the saw preferably 4-cycles a little at max
				speed. Furthermore, the chain must not rotate at idling. A too lean
•	When the saw has been ”run-in” the carburetor should be
				adjusted low speed needle L may cause starting difficulties and
	finely adjusted. The fine adjustment should be carried out
				bad acceleration. A too lean adjusted high speed needle H gives
	by qualified person. First adjust the L-jet, then the idling
				lower power=less capacity, bad acceleration and/or damage to the
	screw T and then the H-jet.
				engine. A too rich adjustment of the two speed needles L and H
				gives acceleration problems or too low working speed.

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