Husqvarna 340, 345 and 350: fuel and service identity
The cited 340/345/350 manual specifies BPMR7A or RCJ7Y plugs at 0.5 mm, a 0.50 L fuel tank and a separate0.25 L chain-oil tank. Its50:1 premix instruction concerns gasoline and two-stroke oil. The two tank volumes are not a mixing ratio, and a later Rancher or XP Mark II kit is not identified by this older saw family.
Two reservoirs perform different jobs
The published fuel tank is twice the chain-oil tank’s volume: 0.50 L versus0.25 L. That does not mean mixing gasoline and oil two-to-one. The engine uses the manual’s 50:1 fuel, while chain lubricant goes in the separate reservoir.
For a measured one-liter gasoline batch at 50:1, the two-stroke oil amount is 20 ml. Use an approved container and the manual’s specified fuel, oil and mixing procedure. A partly filled tank is not a measuring vessel for the fuel mixture.
A plug gap is not a parts identity
This manual lists BPMR7A or RCJ7Y at 0.5 mm. The 545/550XP Mark II family instead uses CMR6H in its own document. Identical gap figures do not establish that the plug’s body, heat range or construction is interchangeable.
| 340/345/350 system or part | Operator-manual identity |
|---|---|
| Fuel reservoir | 0.50 L |
| Chain-oil reservoir | 0.25 L |
| Specified plug families | BPMR7A /RCJ7Y |
| Plug gap | 0.5 mm |
Keep attachment and safety checks with the saw
Use the approved cutting-attachment combinations for the actual model and revision. A drive-link count alone omits pitch, gauge and bar compatibility. Record the installed attachment rather than buying a chain only by nominal bar length.
The cited maintenance instructions include monthly plug replacement, or sooner when required, alongside the operating checks. A failed brake, moving chain at idle, damaged controls or a lubricant fault needs correction before cutting. Use the complete service procedure for repairs rather than a generic carburetor setting from a different generation.
340/345/350 manual, Husqvarna 545/550XP Mark II plug documentation
Husqvarna 340, 345 and 350 chain saws: fuel mix, spark plug and maintenance
The Husqvarna 340, 345 and 350 run on a 1:50 mix, which is 2½ US fluid ounces of two-stroke oil per gallon of gasoline, and use an NGK BPMR 7A or Champion RCJ 7Y spark plug gapped 0.5 mm. The fuel tank holds 0.5 liter and the chain oil tank 0.25 liter. Husqvarna says to replace the plug after about a month in operation.
Stop the engine and let the muffler cool before servicing, and wear cut-resistant gloves and eye protection.
Three Husqvarna saws, one plug and one mix
The Husqvarna 340, 345 and 350 share one manual. They are two-stroke saws of 40.8, 45.0 and 51.7 cubic centimeters, rated 2.0, 2.2 and 2.3 kW at 9,000 RPM, with an idle speed of 2,700 RPM. They use the same spark plug, gap, mix and tank sizes: a 0.5 liter fuel tank and a 0.25 liter chain oil tank.
| Item | Specification |
|---|---|
| Cylinder volume | 40.8 cc (340); 45.0 cc (345); 51.7 cc (350) |
| Bore and stroke | 40, 42 and 45 mm bore; 32.5 mm stroke |
| Power at 9,000 RPM | 2.0 kW (340); 2.2 kW (345); 2.3 kW (350) |
| Idle speed | 2,700 RPM |
| Spark plug | NGK BPMR 7A or Champion RCJ 7Y |
| Electrode gap | 0.5 mm (0.020 in) |
| Fuel mix | 1:50 (2%) Husqvarna two-stroke oil to gasoline; octane 87 or higher |
| Fuel tank | 0.5 L (1.06 US pint) |
| Chain oil tank | 0.25 L (0.53 US pint), automatic oil pump |
| Weight, empty, without bar and chain | 10.3 lb (4.7 kg) for the 340 and 345; 10.6 lb (4.8 kg) for the 350 |
Two-stroke oil at 1:50
| Gasoline | Two-stroke oil |
|---|---|
| 5 liters | 0.10 liter |
| 10 liters | 0.20 liter |
| 15 liters | 0.30 liter |
| 20 liters | 0.40 liter |
| 1 US gallon | 2½ US fl oz |
| 2½ US gallons | 6½ US fl oz |
Never use oil made for water-cooled outboard engines or oil intended for four-stroke engines. Chain oil is a separate product: the chain lubrication is automatic and Husqvarna recommends a special chain oil, never waste oil, and one of the right grade for the air temperature.
Maintenance the manual lists
| When | What |
|---|---|
| Daily | Clean the air filter as necessary, check the throttle trigger and lockout, clean and check the chain brake, check bar and chain oiling, sharpen and check the chain. |
| Weekly | Clean the spark plug and check the 0.5 mm gap; clean flywheel fins, the cylinder cooling fins and the spark arrestor mesh; clean the carburetor compartment. |
| Monthly | Clean the inside of the fuel and oil tanks; check the fuel hose; change the spark plug and the air filter; check the chain brake band and clutch. |
| Idle speed | Adjust with the T-screw; if the chain moves at idle, take it to a dealer. |
Husqvarna says the spark plug should be replaced after about a month in operation, and warns that using the wrong plug type can damage the piston and cylinder. Husqvarna says the fuel filter must be replaced at regular intervals.
Parts to buy for the Husqvarna 340, 345 and 350 chain saws
| Part | Part number | Notes |
|---|---|---|
| Air filter (felt) | 537024003 | Fits the 340, 345, 350 and related models. |
| Spark plug | NGK BPMR 7A or Champion RCJ 7Y | Gap 0.5 mm (0.020 in). |
Husqvarna also sells a 340, 345, 350, 351, 353 and 346XP tune-up kit with a fuel filter, air filter and spark plug.
1:50
Fuel mix
2½ oz of oil per US gallon.
BPMR 7A
NGK spark plug
Or Champion RCJ 7Y; gap 0.5 mm.
0.5 L
Fuel tank
0.25 L chain oil tank.
How the 340, 345 and 350 compare
Fire and Saw puts the three saws in one family and says the 350 has the best power-to-weight ratio, a good bit more powerful than the 340 and 345 while only slightly heavier, and that the 340 has the worst, weighing the same as the 345 and being less powerful.
Best Professional Chainsaw gives the 350 a dry powerhead weight of 10.6 lb and suggests an 18-inch bar with a .325-inch pitch chain for balance, and a TractorByNet thread shows buyers weighing the cheaper 345 with a 16-inch bar against the 350 with an 18-inch bar.
Husqvarna 340, 345 and 350 chain saws: questions
What is the fuel mix for a Husqvarna 350 chainsaw?
1:50 (2%) Husqvarna two-stroke oil to gasoline. That is 2½ US fluid ounces per US gallon, 6½ ounces per 2½ gallons, or 0.10 liter per 5 liters.
What spark plug does a Husqvarna 350 use?
An NGK BPMR 7A or a Champion RCJ 7Y, with an electrode gap of 0.5 mm (0.020 inch). Husqvarna warns that using the wrong plug can damage the piston and cylinder.
How often do I replace the Husqvarna 350 spark plug?
Husqvarna says after about a month in operation, or earlier if necessary. Clean the outside of the plug and check the gap every week.
How big is the Husqvarna 350 fuel tank?
0.5 liter (1.06 US pint). The chain oil tank holds 0.25 liter and the oil pump is automatic.
How big are the Husqvarna 340, 345 and 350 engines?
40.8 cc, 45.0 cc and 51.7 cc, rated 2.0, 2.2 and 2.3 kW at 9,000 RPM. All three idle at 2,700 RPM.
What oil should I mix in a Husqvarna 350?
Husqvarna two-stroke oil, specially formulated for its engines, at 1:50. Never use oil for water-cooled outboard engines or four-stroke engine oil.
What chain oil should I use in a Husqvarna 350?
A special chain oil with good adhesion. Where none is available the manual says transmission oil can be used, but never waste oil, which damages the pump, bar and chain.
What gasoline should I use in a Husqvarna 350?
Unleaded gasoline with an octane rating of at least 87, and a higher octane for continuous high revs such as limbing. Lower octane can cause knocking and engine damage.
How do I adjust the idle speed on a Husqvarna 350?
Use the T-screw: turn it clockwise to raise the idle speed and anti-clockwise to lower it. The recommended idle speed is 2,700 RPM. If the chain moves at idle, take it to a dealer.
How often do I clean the Husqvarna 350 air filter?
Daily or more often in demanding conditions. Husqvarna says an old filter cannot be cleaned completely and must be replaced at regular intervals, monthly per its list.
How much does a Husqvarna 350 weigh?
10.6 pounds (4.8 kg) for the 350 and 10.3 pounds (4.7 kg) for the 340 and 345, without bar or chain and with empty tanks.
What is the Husqvarna 350 air filter part number?
Husqvarna 537024003 is the felt air filter for the 340, 345 and 350. Husqvarna also sells a tune-up kit for the 340, 345, 350, 351, 353 and 346XP with a fuel filter, an air filter and a spark plug. The plug is an NGK BPMR 7A or Champion RCJ 7Y.