Stihl MS 440/044 Chainsaw

SECTION: Tools and EquipmentISSUED: 02-2011 REVISED: ##-####

Objectives

• To provide an understanding of the following– Specifications– Use– Maintenance– Safety

Specifications

• STIHL MS 440/044

• 20” Bar

• Chain

– 33 cutting teeth

– Carbide tipped

• HD air filter with pre-filter

• 2 stroke engine

• 5.2 horse power

• 50:1 pre mix

• Spark plug

– Bosch WSR6 F or NGK BPMR 7A

• Idle RPM-2,500

• Max RPM-13,500

Use

• Vertical ventilation• Forcible entry• Cutting timber and

brush• Cutting lumber

– Shoring operations

Control Lever Positions

• Stop

• Run

• Half choke

• Choke

Interlock and throttle must be depressed

to switch from run to half choke or choke

Parts

• Chain brake– Manual and inertia

operated

• Decompression valve– Allows for an easier

and quicker start

Parts

• Chain catch– Reduces risk of operator

contact with chain should it break or derail

• Chain tensioner– Allows for chain tension

adjustment

Starting Procedures

• Ground starting method– Place saw on ground– Disengage chain

break– Ensure control lever

is in choke position– Hold handle firmly

with left hand

Starting Procedures

• Place foot firmly in handle

• Pull starter grip• Repeat until engine fires• Adjust control lever to

half choke• Pull starter grip until saw

starts and runs

Starting Procedures

• Quickly depress interlock and throttle– Places saw in run

position• Do not pull start rope to

its full extension

Starting Procedures

• Drop starting method– Ensure brake is

disengaged– Ensure control lever

is in choke– Hold handle with left

hand– Hold starter grip with

right hand

Starting Procedures

• Raise saw slightly above waist

• Let saw drop in a controlled manner– Pulling starter grip

• Repeat until saw fires• Adjust master control

valve to half choke

Starting Procedures

• Continue to drop and pull starter grip until saw fires and runs

• Quickly squeeze throttle and interlock– Puts saw in run

position• Do not pull start rope to

its full extension

Procedures

• Disengage brake– Rest tip of the saw’s bar

on ground or roof– With left hand, keep

thumb on handle– Pull back on the chain

brake to disengage

Procedures

• Stopping the Chain– Release throttle to bring saw to idle– Engage chain brake with back of left hand while

holding handle• Turn saw off by raising control lever to the stop

(top) position• Always place saw in ready to run position when

placing back into service – Brake disengaged, throttle trigger interlock depressed

and the control lever in the choke position

MaintenanceBasic

• Refuel after use• Refill chain bar oil whenever you refuel• Adjust chain tension ensuring the chain can slide

across the bar– Approximately 1/16” gap between bar and chain

• Rotate guide bar when chain is removed to extend bar life

• Inspect chain for damage– Replace when 3 consecutive teeth or 6 total teeth are

missing or when a tie strap is broken• Saw may need a complete tear down to ensure it is

thoroughly cleaned of all dirt and debris– Pay extra attention to the cooling fins. Over time they can

accumulate “gunk” and cause the saw to overheat.

MaintenanceAdvanced

• Recommended tools– Scrench

• Stihl combination wrench

– Stihl flathead screwdriver– Larger flathead screwdriver– Stihl provided torques style

wrench– Cleaning solvent or WD-40

Air Filter System

• Set master control lever to full choke

• Open the twist lock above and remove the carburetor box cover

Air Filter System

• Remove filters and check outer butterfly position– Ensure its closed

• Separate filter components• Clean filters by using

compressed air– Blowing from the inside out

• In case of stubborn dirt, wash filters with warm soapy water– Rinse from the inside out

• Let air dry

Outer Butterfly

Felt Prefilter HD Filter Standard Filter

Clutch and Chain Assembly

• Unscrew the nuts and remove chain sprocket cover– Note side of stamped

serial numbers or graphics on chain bar

• Bar must be flipped when re-installed

Stamped Serial #

Chain and Bar Removal

• Loosen chain by turning tensioning screw counterclockwise

• Once chain starts to sag on the bottom of the bar, remove the bar and chain

Chain Tensioning Screw

Chain and Bar Cleaning

• Use parts cleaner to thoroughly clean chain and bar

• Inspect chain and determine if it needs to be out of service.– 3 missing teeth in a row– 6 missing teeth total– 1 broken link

• Use a small screwdriver to remove debris from the bar chain guide

• Use compressed air to blow excess solvent from the chain and bar and dry with a rag

Powerhead Cleaning

• Remove the inner side mounting plate by removing the screw adjacent to the tensioning screw

• Remove the chain catcher with the Stihl torx wrench

Powerhead Cleaning

• Removing the E clip from the crank shaft using small screwdriver

• Remove clutch drum assembly

• Place the needle cage in a cap full of bar oil to lube

E-Clip

Washer

Clutch Drum

Rim Sprocket

Needle Cage

Powerhead Cleaning

• Use compressed air to blow as much debris off of the powerhead

• Remove the two cover plates using the Stihl torx wrench

• Use the parts cleaner to further clean the powerhead– Use caution with the solvent

avoiding the carburetor intake

• Clean thoroughly • Use compressed air to blow off

any excess solvent and dry with a rag

Powerhead Cleaning

• Clean all parts using the parts cleaner

• Use compressed air to blow off excess solvent and dry with a rag

• Set aside once cleaned and try to keep everything organized

Chainsaw Reassembly

• Now reassemble the powerhead in reverse order• Starting with the following

– 2 cover plates– Clutch drum assembly

• When installing the clutch drum, rotate and apply slight pressure until the oil pump drive spring engages the slot on the outside diameter of the drum

• There should be a noticeable connection when the drum catches and drops into place

• The slot on the drum is identified with a mark located on the face of the drum

Chainsaw Reassembly

• Continue reassembling in the following order– Chain catcher– Inner side plate– Bar and chain– Sprocket cover– Air filter– Carburetor box cover

Chainsaw Reassembly

• Replace bar and chain• Ensure the bar is flipped

to the opposite side from where it was initially assembled– This will help with wear

over time

• Ensure the chain is properly seated in the bar and sprocket

Chainsaw Reassembly

• Apply tension to the chain by turning the chain tension screw clockwise– Take some of the sag

out of the chain

• Install the sprocket cover and finger tighten the two nuts

Chainsaw Reassembly• Adjust the tension of the chain• Appropriate tension has been applied when:

– With a gloved hand, pull the chain upward from the middle of the bar to create a gap equal to the width of a nickels edge being exposed between the chain and bar

– With the chain brake off, the chain can be spun around the bar• Use the Scrench to finish tightening the sprocket cover nuts until snug

– Do not over tighten

Chainsaw Reassembly• Refuel with 2 stroke pre-mix 50:1 fuel• Top off bar oil• Test Run

– Ensure adequate chain lubrication by running at full throttle and aiming saw towards the ground

– A light spray pattern of oil should begin to form on the ground• Adjust if necessary

• Re-adjust chain tension if necessary• Place back into service in the “Ready Run Position”

Chainsaw Maintenance

• Refer to Stihl Owner’s Manual for further maintenance needs – http://www.stihlusa.co

m/stihl_ownersmanuals/044_Manual.pdf

Safety

• Always wear proper PPE when operating chainsaws.– Minimum- helmet, eye protection, gloves,

and hearing protection while performing maintenance

• Avoid cutting overhead and inline with body• Maintain a firm grip at all times• Cut at full throttle

Safety

• Common reactive forces when cutting– Kickback

• Occurs when saw chain near upper quadrant of bar nose contacts a solid object causing the saw to fling up and back in an uncontrolled arc

– Pushback• Occurs when the chain on the top of the bar is suddenly

stopped or caught, driving the saw straight back into the operator

– Pull in• Occurs when the chain on the bottom of the bar is

suddenly stopped or caught, causing the saw to be pulled forward

• Let the saw cool before refueling