When tuning up a Husqvarna chainsaw you must make sure your air filter is clean. A can of starting fluid works great for this. Take your air filter off of the saw, split it in half (there is a seam along the center of the sides with a tab that you can separate using your combination screw driver/wrench), spray the filter from the inside to the outside, brush off any debris with a soft brush (an old tooth brush works great for this), and if you have access to an air compressor, give it a blast of air to get every thing out, also from the inside out. A clean filter is critical to a finely tuned chain saw.
With the saw shut off, turn in the high and low speed jets till you feel them bottom out. Back each one out 3/4 of a turn. The owners manual of some saws may say a little more, especially on the high speed, but 3/4 should get you started for most saws. Start the saw up, get it “warmed up”, and adjust the idle so the chain isn’t going around. With the saw running at an idle, adjust the low speed to where you get the maximum rpms on saw.keep your hand off of the throttle for this part.
Once you have done this, reset the idle, if necessary. At this point, you should have immediate response when you hit the throttle. If there is some hesitation, the low speed may need to be opened up a bit. Now, with the saw on the ground, or on a stump, or some place here NOTHING can or will come in contact with the chain, adjust the high speed. You’ll have to hold the throttle down while you turn in the high speed jet. Adjust the jet till you hear the saw “peak”, then open it up a bit, about 1/4 of a turn. Your saw should now be a lean, mean, screaming cutting machine. There should be no hesitation when you hit the throttle, and it should get to max rpm’s right away. If your saw is still bogging down at top end, try changing the fuel filter. If you still have problems, get a kit and rebuild the carb. The lever in the bottom of the carb may be out of whack. The kit will consist of a couple gaskets, a needle, a little lever with a slot in the one end that holds on to the needle, and a diaphragm.
Here you should have an air compressor to blow the dust and chips out of the way, and to blow through all the little openings in the carb once you get it stripped down. Where the gas enters the carb, there’s a little screen you may have to replace….that keeps stuff from getting into the rest of the carb. Make sure that this area is clean. When you reassemble the carb, make sure the lever is level. Set the carb on your work bench upside down, and bend the lever slightly where the needle’s hooked on to get the lever level. Then make sure you get the little tab on the diaphragm hooked up before you reinstall the bottom cover.