My stihl fs120 single screw model, what is correct method of mixture screw adjustment

SOURCE: STIHL CHAINSAW MIXTURE SETTINGS

one turn high and low 66 has compesator carby willrun rich up high but will lean under load

SOURCE: ryobi 31cc lawn trimmer carb adjustment

As with all 2 strokes if you have compression and a reasonable spark, you only need fresh fuel with correct oil ratio) and they must go !(as long as you haven't fiddled first and all gaskets are sealing) I start mine by(1) pumping the primer till it is firm,(2) full choke,(3) pull till it kicks ONCE,(4) half choke, pull till it runs,allow to warm up and(5) switch to run (you may need to apply a bit of throttle while pulling as in (4)(or give it a few more pumps if it dies) If all is ok, check that when properly warmed up there is a smooth transition from idle to full revs, if it hesitates it may need the LOW SPEED mixture leaning (clockwise) SLIGHTLY.If it dies the LOW SPEED mixture may need richening(anti-clockwise)(adjust 1/8 turn at a time) Make sure that motor is just peaking at full revs and is on the RICH side of peaking (HIGH SPEED mixture)(this will avoid seizing it Adjust both till it revs cleanly and is JUST rich at full, and idleing nicely and it should start without too much trouble.(If you have fiddled and are lost,-about 2 1/2 turns out from closed on both needles should get you started)

Mike Butler

• 6674 Answers
• Posted on Apr 04, 2009

SOURCE: I don't know where the air/fuel mixture screw is on my carb

There should be one screw (I'm assuming it's the Carter YF carburetor 1 barrel) that's by itself away from linkages etc, more to center at base of carb where it meets manifold, that is angled approx 45 degrees going in to base. That should be your mixture screw. What symptoms are you experiencing anyway?

SOURCE: What is the correct fuel mixture for this machine

Every Stihl I have ever touched requires 40:1 fuel mixture.

SOURCE: stihl chainsaw

I have a stihl ms 180 that leaks bar oil all the time