Husqvarna 120 Mark II Owner Manual - Page 20

Intermittent maintenance • Have an approved service center repair or replace the muffler after 50 hours of operation. • Do maintenance on the spark plug when: • the power level in the engine is low. • it is hard to start the engine. • the engine does not work correctly at idle speed. • Do a check of the saw chain lubrication each time you refuel. See To do a check of the saw chain lubrication on page 21. To adjust the idle speed Make sure that the air filter is clean and the air filter cover is attached before you adjust the idle speed. 1. Turn the idle adjustment screw, which is identified with a "T" mark, clockwise until the saw chain starts to turn. 2. Turn the idle adjustment screw, which is identified with a "T" mark, counterclockwise until the saw chain stops. 3. The idle speed must be below the speed when the saw chain starts to turn. The idle speed is correct when the engine operates smoothly in all positions. To clean the spark arrester screen 1. Use a wire brush to clean the spark arrester screen. To do maintenance on the spark plug CAUTION: Use the recommended spark plug. Make sure that the replacement is the same as the manufacturer supplied part. An incorrect spark plug can cause damage to the product. 1. If the product is hard to start or operate, examine the spark plug for unwanted materials. To decrease the risk of unwanted material on the spark plug electrodes: a) make sure that the idle speed is correctly adjusted. b) make sure that the fuel mixture is correct. c) make sure that the air filter is clean. 2. Clean the spark plug if it is dirty. Make sure that the electrode gap is correct. (Fig. 72) 3. Replace the spark plug when it is necessary. To clean the air filter 1. Remove the air filter cover and remove the air filter. 2. Clean the air filter with warm soap water. Make sure that the air filter is dry before you install it. 3. Replace the air filter if it is too dirty to fully clean it. Always replace a damaged air filter. To sharpen the saw chain The cutter The cutting part of the saw chain is called the cutter and consists of a cutting tooth (A) and the depth gauge (B). The cutters cutting depth is determined by the difference in height between the two, the depth gauge setting (C). (Fig. 73) When you sharpen a cutting tooth there are four important factors to remember: • Filing angle. (Fig. 74) • Cutting angle. (Fig. 75) • File position. (Fig. 76) • Round file diameter. (Fig. 77) To sharpen the cutting teeth Use a round file and a file gauge to sharpen the cutting teeth. SeeSaw chain filing and saw chain combinations on page 23 for information on the recommended dimension of the file and gauge for the saw chain installed on your product. 1. Make sure that the saw chain is correctly tensioned. A slack chain will move sideways, making it more difficult to sharpen correctly. 2. File all teeth on one side first. File the cutting teeth from the inside face and reduce the pressure on the return stroke. 3. Turn the product over and file the teeth on the other side. 4. File all the teeth to the same length. When the length of the cutting teeth is reduced to 4 mm (5/32") the saw chain is worn out and must be replaced. (Fig. 78) To adjust the depth gauge setting Sharpen the cutting teeth before you adjust the depth gauge setting. See To sharpen the cutting teeth on page 20. When you sharpen the cutting tooth (A), the depth gauge setting (C) will decrease. To maintain optimal cutting performance, the depth gauge (B) has to be filed down to achieve the recommended depth gauge setting. See Saw chain filing and saw chain combinations on page 23 to find the correct depth gauge setting for your particular chain. (Fig. 79) (Fig. 80) Note: This recommendation assumes that the length of the cutting teeth is not reduced excessively. 20 654 - 007 - 05.05.2020