Resetting the air/fuel mixture after installing your MaxFlow

RESET PROCEDURE FOR THE STIHL CHAINSAW CARBURETOR

After installing a new MaxFlow® filter, it is likely that you will need to make a slight adjustment to the air/fuel mixture of the carburetor.  Most Stihl Chainsaws have a high speed carburetor adjusting screw on the the right side of the saw, and generally this is the adjustment that you will need to change. Consult your owners manual for instructions on how to correctly adjust this for the optimum RPM and power.  As a general rule, the saw should NOT be tuned to the highest RPM it will spin at no load (meaning the saw is not cutting).  It is best to adjust the RPM to a slightly rich condition when free spinning a chain to where the saw is slightly 4 cycling (missing), but as soon as the saw is placed into the cut the saw tone should immediately clear and run smoothly.  This is not a perfect method, and a RPM tachometer should be used as a check to prevent a lean condition.

RESET  PROCEDURE FOR THE M-TRONIC MS661 CARBURETOR

The Stihl MS661 is equipped with an Auto-tune function that normally will self adjust for altitude and air filter caused changes in air pressure.  Switching from an old used HD2 filter to a new MaxFlow filter will allow additional airflow to the carburetor and also cause this auto tune function occur.  In the event that this does not automatically occur, here is the procedure reset the saw.

To reset the carburetor to the original factory setting.
a. Engage the chain brake
       b. Hold throttle and set start lever to the Start position (Δ)
c. Start saw and let idle in Start position (Δ) for 90 seconds
d. Release chain brake and blip throttle to bring the machine to the Run position (I)
e. Immediately move lever to Stop position (O)
 

To calibrate the idling characteristics of the saw.
a. Engage the chain brake
b. Hold throttle and set start lever to Start position (Δ)
c. Start saw

                        d. Release chain brake and blip throttle to bring the machine to the Run position (I)
e. Let idle in Run position (I) for 90 seconds
f. Immediately move lever to Stop position (O)
 

To calibrate the full throttle characteristics of the saw.

                        a. Engage the chain brake

                        b. Hold throttle and set start lever to Start position (Δ)
c. Start saw, release the chain brake

                        d. Blip throttle to bring the machine to the Run position (I)
e. Make five uniform cuts through a minimum 12-inch-diameter log.