Stihl MS 171 Manual Download Page 18

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MS 171, MS 181, MS 211

4.7

Engine

Always check and, if necessary,
repair the following parts before
looking for faults on the engine:

- Air filter
- Fuel system
- Carburetor
- Ignition system

Condition

Cause

Remedy

Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle

Oil seals in engine damaged

Replace the oil seals

Engine leaking or damaged
(cracks)

Seal or replace the engine

Engine does not deliver full power
or runs erratically

Piston rings worn or broken

Fit new piston rings

Muffler / spark arresting screen
carbonized

Clean the muffler (inlet and
exhaust), replace spark arresting
screen, replace muffler if necessary

Air filter element dirty

Replace air filter element

Fuel hose severely kinked or
damaged

Fit new hose or position it free from
kinks

Tank vent faulty

Check tank vent and replace if
necessary

Air valve does not open

Check air valve and replace if
necessary

Engine overheating

Insufficient cylinder cooling. Air
inlets in fan housing blocked or
cooling fins on cylinder very dirty

Thoroughly clean all cooling air
openings and the cylinder fins

All manuals and user guides at all-guides.com

Summary of Contents for MS 171

Page 1: ...STIH STIHL MS 171 181 211 2007 05 All manuals and user guides at all guides com a l l g u i d e s c o m...

Page 2: ...33 8 6 Crankshaft 34 8 7 Ball Bearings Crankshaft 36 8 8 Piston 37 8 8 1 Piston Rings 39 9 Ignition System 40 9 1 Ignition Module 40 9 1 1 Removing and Installing 40 9 2 Ignition Timing 42 9 3 Testing...

Page 3: ...e Shutter 82 14 4 9 Adjusting Screws 85 14 5 Adjusting the Carburetor 86 14 5 1 Basic Setting 86 14 5 2 Standard Setting 87 14 6 Choke and Throttle Rods 87 14 7 Removing and Installing the Intake Mani...

Page 4: ...tools in the STIHL Special Tools manual which lists all the special servicing tools currently available from STIHL Symbols are included in the text and pictures for greater clarity The meanings are as...

Page 5: ...nce with local environmental regulations 533RA000 TG 2 Safety Precautions If the engine is started up in the course of repairs or maintenance work observe all local and country specific safety regulat...

Page 6: ...tch without linings Clutch engages at 5 100 rpm 5 100 rpm 5 100 rpm Crankcase leakage test at gauge pressure 0 5 bar under vacuum 0 5 bar 3 2 Fuel System Carburetor leakage test at gauge pressure 0 8...

Page 7: ...ne housing repair solution 2 0 Screw D 5x16 Cover chain brake engine housing repair solution 2 0 Countersunk screw M 6x14 Replacement chain catcher repair solution 4 0 Screw P 5x20 Filter base engine...

Page 8: ...lockwise until it drops down slightly Tighten the screw clockwise to the specified torque This procedure ensures that the screw engages properly in the existing thread and does not form a new thread a...

Page 9: ...ed screw LA counterclockwise Clutch springs stretched or fatigued Replace the clutch springs or install new clutch Clutch spring hooks broken Replace the clutch springs Clutch shoe bores worn Replace...

Page 10: ...cket worn Fit new chain sprocket Saw chain stops under load at full throttle Clutch shoes badly worn Install new clutch Clutch drum badly worn Install new clutch drum Brake band blocked Check freedom...

Page 11: ...not properly fitted or damaged Fit oil intake hose properly or install new hose Machine losing chain oil Oil pump body engine housing damaged Check engine housing and oil pump and replace if necessary...

Page 12: ...crankshaft does not turn Guide peg on pawl or pawl itself is worn Fit new pawl Spring clip on pawl fatigued Fit new spring clip Versions with ErgoStart Spring worn or fatigued Fit new ErgoStart sprin...

Page 13: ...module and flywheel Set air gap correctly Flywheel cracked or has other damage or pole shoes have turned blue Install new flywheel Ignition timing wrong flywheel out of adjustment key in flywheel has...

Page 14: ...ulty insulation or short in short circuit wire Check short circuit wire for short circuit to ground Break in ignition lead or insulation damaged Check ignition lead replace ignition module if necessar...

Page 15: ...e the inlet control lever and refit it correctly Perforated disc on diaphragm is deformed and presses constantly against the inlet control lever Fit a new metering diaphragm Poor acceleration Setting...

Page 16: ...air valve replace if necessary Air valve stiff Check air valve replace if necessary Throttle rod stiff throttle shutter does not close Replace throttle rod and lever Engine stalls at idle speed Idle j...

Page 17: ...crew H too rich Check basic carburetor setting correct if necessary Main jet bores or ports blocked Clean the carburetor Pump diaphragm damaged or fatigued Fit new pump diaphragm Engine running extrem...

Page 18: ...ings worn or broken Fit new piston rings Muffler spark arresting screen carbonized Clean the muffler inlet and exhaust replace spark arresting screen replace muffler if necessary Air filter element di...

Page 19: ...snaps into position Remove the screw arrow Remove the cover plate 1 and adjusting wheel 2 1 165RA006 TG 1 165RA007 TG 2 1 533RA005 TG When installing the adjusting wheel check that its teeth face the...

Page 20: ...locking strip 1 0000 893 5904 into the spark plug hole until it butts against the cylinder wall arrow as shown Unscrew the clutch 1 Note that the clutch has a left hand thread Disassembling Clamp the...

Page 21: ...rows must be properly attached Cover washer 1 must be in position It is correctly fitted when TOP arrow faces outwards Position the clutch on the crankshaft stub so that the raised hexagon arrow faces...

Page 22: ...crankshaft stub b 16 Inspect the clutch drum 1 for signs of wear If there are signs of serious wear on the inside diameter of the clutch drum 1 check the remaining wall thickness If it is less than a...

Page 23: ...t come to an abrupt stop The braking time is in order if deceleration of the saw chain is imperceptible to the eye If the chain brake does not operate properly refer to troubleshooting b 4 2 7 2 Remov...

Page 24: ...band 1 into its seat arrow as far as stop Engage pegs on cover 1 in the holes arrows and push it fully home 533RA059 TG 1 533RA027 TG 1 TOP 1 533RA026 TG If the pegs have broken off the cover can be s...

Page 25: ...tle then push it to the left as far as the hole arrow and remove it Remove the spacer sleeve from the brake lever Pull the hand guard 1 and brake lever 2 off the pivot pins arrows together Remove the...

Page 26: ...uard at the starter side and fit the screw Push on the spacer sleeve Fit the strap 1 Fit the E clip 2 The turns of brake spring must be tightly against one another in the relaxed condition If this is...

Page 27: ...2 in the direction of the engine use suitable support Use a suitable punch to drive out the pin 3 in the direction of the clutch use suitable support Before installing the new pin 1 coat its knurled...

Page 28: ...and replace if necessary Clean all disassembled parts b 16 Lubricate the chain tensioner with STIHL multipurpose grease b 16 Install in the reverse sequence 1 533RA057 TG 2 4 2 1 3 2 533RA058 TG 7 7...

Page 29: ...o pull out the spark arresting screen 1 if fitted Clean the spark arresting screen 1 and replace if necessary Install in the reverse sequence Inspect and clean the sealing faces arrows b 16 Position m...

Page 30: ...piston to top dead center This can be checked through the inlet port Fit spark plug 1 and tighten it down firmly Tightening torques b 3 5 533RA008 TG 1 Pry the plugs arrows out of the muffler Take ou...

Page 31: ...Continue with pressure test b 8 2 3 8 2 3 Pressure Test Carry out the same preparations as for the vacuum test b 8 2 2 Always carry out the vacuum test before the pressure test b 8 2 2 Connect pressu...

Page 32: ...b Cleaning the sealing face b 16 Lubricate sealing lips of new oil seal with grease b 16 Apply thin coating of sealant b 16 to the outside diameter of the oil seal Slip the oil seal closed side facing...

Page 33: ...e facing the engine over the installing sleeve Remove the installing sleeve 1 Use press sleeve 1 1123 893 2400 to install the oil seal 2 Wait about one minute then rotate the crankshaft several times...

Page 34: ...r Remove the shroud b 8 4 Remove the chain sprocket cover bar and chain b 5 Remove the muffler b 8 1 Remove the clutch b 6 Remove the ignition module b 9 1 Remove the wiring harness b 9 6 2 Remove the...

Page 35: ...e pan and cylinder must line up Fit and tighten down the cylinder mounting screws arrows Install the worm b 8 3 Reassemble all other parts in the reverse sequence Tightening torques b 3 5 Carry out le...

Page 36: ...03 1585 if the engine has been opened up Push the installing sleeve 1 1118 893 4602 onto the crankshaft Push the new oil seals open side facing the crankshaft onto the crankshaft stubs Fit the retaini...

Page 37: ...any way Replace parts with damaged mating faces Apply sealant along the groove b 16 Sealant must not get into the recesses arrows the transfer ports must not be obstructed Place the engine pan 1 on t...

Page 38: ...the needle bearing with oil Install the piston b 8 8 Install the crankshaft and oil seals b 8 6 Install the engine b 8 5 8 8 Piston Remove the engine b 8 5 Remove the crankshaft b 8 6 Use a suitable...

Page 39: ...the sleeve 1 from the installing tool 5910 890 2210 Attach the snap ring 1 to the magnet 2 so that the snap ring gap is on the flat side of the tool s shank arrow Push the large slotted diameter of th...

Page 40: ...1 Check the oil seals and ball bearings and replace if necessary b 8 7 Install the crankshaft b 8 6 Install the engine b 8 5 8 8 1 Piston Rings Remove the piston b 8 8 Remove the piston rings from the...

Page 41: ...tage output with ignition lead 1 the connector tag 2 for the short circuit wire Testing in the workshop is limited to a spark test A new ignition module must be installed b 9 1 if no ignition spark is...

Page 42: ...inst the upper hole Secure the insulator 1 with the lugs arrows on the bosses Position the ignition module 1 so that the ignition lead 2 is on the left and insert the screw arrow with washer do not ti...

Page 43: ...during repair work Since there is no mechanical wear in these systems ignition timing cannot get out of adjustment 9 3 Testing the Ignition Module To test the ignition module use either the ZAT 4 ign...

Page 44: ...ccelerate during the test If a spark is visible the ignition system is in order If no spark is visible in the window 3 check the ignition system with the aid of the troubleshooting chart b 9 7 9 4 Spa...

Page 45: ...Tap the end of the puller a few times to release the flywheel Unscrew the puller and remove the flywheel 533RA157 TG 533RA158 TG 1 533RA159 TG Inspect flywheel 1 and magnet poles 2 for cracks or other...

Page 46: ...nce 533RA161 TG 1 9 6 2 Removing and Installing The short circuit and ground wires are combined in a wiring harness If damaged the complete wiring harness must be replaced When cleaning the machine ta...

Page 47: ...RA166 TG 1 2 533RA167 TG 1 2 Fit the wiring harness 1 along the housing and push it ground wire first completely into the guide arrow Push ground wire connector with protective tube 2 onto the contact...

Page 48: ...or prevent operation of the short circuit wire Always check ground wire for contact and continuity The short circuit and ground wires are combined in a wiring harness If damaged the complete wiring h...

Page 49: ...nintentional disconnection 533RA169 TG 1 2 533RA173 TG 1 Check operation the short circuit wire s connector must touch the contact spring arrow in position 0 The ground and short circuit wires must be...

Page 50: ...correct Contacts shorted Clean or replace the plug b 9 3 Check spark plug boot Firmly seated on plug leg spring Leg spring hook in center of ignition lead Boot damaged If necessary install new spark...

Page 51: ...ng Spark plug boot Holes cracks Resistance spark plug boot to ground spec 1 5 12 k If necessary install new spark plug boot and or ignition lead with ignition module b 9 4 Check ground and short circu...

Page 52: ...tem or carburetor Check engine for leaks Check position of flywheel on crankshaft b 8 2 b 9 5 yes Check operation of switch shaft Short circuit wire chafed Does contact spring make contact with short...

Page 53: ...rter post with STIHL special lubricant If clogged with dirt or pitch the entire starter mechanism including the rewind spring must be removed and disassembled Take particular care when removing the sp...

Page 54: ...ight part of the spring clip 1 ease it out of the groove and pull the spring clip off the starter post the rewind spring may pop out during this operation Remove and inspect the pawls 2 clean or repla...

Page 55: ...d position arrows Push the pawls 1 onto the pivot pins 2 on the flywheel and locate the ends of the torsion springs against the ribs arrow Install the E clips 533RA197 TG 1 2 3 3 4 4 533RA198 TG 1 1 5...

Page 56: ...ry Coat bore in rope rotor with STIHL special lubricant b 16 Lubricate starter post with oil b 16 Fit the rope rotor 2 on the starter post so that the inner spring loop arrow engages the recess 1 Fit...

Page 57: ...maining rope out of the sleeve Inspect the individual parts and replace if necessary Do not shorten the starter rope 165RA230 TG 1 165RA231 TG Thread the new starter rope through the sleeve Tie a simp...

Page 58: ...the rewind spring Hold the rope rotor 2 steady Pull out the twisted rope 1 with the starter grip and straighten it out 533RA209 TG 1 2 533RA210 TG 1 2 Hold the starter grip 1 firmly to keep the rope t...

Page 59: ...out during this process Remove the spring housing Check that the new rewind spring 1 is properly seated and the anchor loop is engaged on the lug arrow If the rewind spring has popped out refit it in...

Page 60: ...Start The same procedures are used here as for the standard version The differences are the anchor loop and the installed position of the spring The open side of the anchor loop arrow must face inward...

Page 61: ...ug 1 Inspect the anti vibration spring and plug and replace if necessary Screw home the bearing plug 1 as far as stop Screw the anti vibration spring 2 into the handle frame arrow as far as stop 533RA...

Page 62: ...rames Insert screw and tighten it down firmly Lift the handle frame a little and handle frame push the anti vibration spring over the mount arrow Insert screw and tighten it down firmly Reassemble all...

Page 63: ...gs on oil tank and cylinder Remove the screw arrow Pry the anti vibration springs out of their mounts Pull tank vent hose 1 off the nipple Hold the rear handle turn the handle frame to the right and t...

Page 64: ...sing Insert and firmly tighten down the screws arrows of the anti vibration springs on the oil tank and cylinder 533RA245 TG 1 533RA232 TG Fit screw arrow and tighten it down firmly Check that handle...

Page 65: ...lling Remove the filter base b 14 2 Remove the handle molding b 12 2 Disconnect the throttle rod 1 from the throttle trigger arrow Remove the carburetor b 14 3 Remove the connector arrow of short circ...

Page 66: ...t 1 Ease the switch shaft 1 into the guide until it snaps into position Insert screwdriver through opening in the lever 1 and apply it to the edge arrow Push the lever 1 into the mounts until it snaps...

Page 67: ...ugh the handle frame from below 533RA174 TG 533RA260 TG Remove the handle molding 1 Disconnect the throttle rod 1 from the throttle trigger arrow Pry the interlock lever 1 out of its mounts and lift i...

Page 68: ...Attach the throttle rod 1 to the throttle trigger arrow Make sure the throttle rod is properly located in the mounts b 14 6 Fit forked end arrow of handle molding 1 over the throttle rod mount 533RA2...

Page 69: ...y Install in the reverse sequence 533RA274 TG 1 2 13 2 Oil Suction Hose The oil suction hose is located on the underside of the machine and must be replaced if damaged Open the oil tank cap and drain...

Page 70: ...or the pump itself The worm is removed and installed at the clutch side b 8 3 Remove the handle frame b 11 4 533RA279 TG 1 Pry the oil suction hose 1 out of the oil pump arrow Screw the puller 1 1130...

Page 71: ...ow in the engine housing b 13 2 If necessary inspect the worm and replace it if necessary b 8 3 Install the handle frame b 11 4 Reassemble all other parts in the reverse sequence Tightening torques b...

Page 72: ...led depth of valve a about 2 5 mm Reassemble all other parts in the reverse sequence 533RA293 TG 533RA294 TG 219RA479 TG 13 5 Oil Tank Cap See instruction manual Open the tank cap Disconnect the nippl...

Page 73: ...air filter and clean of replace if necessary see instruction manual Install in the reverse sequence 1 533RA095 TG 14 2 Baffle Filter Base Remove the air filter b 14 1 Use screwdriver 5910 890 2420 to...

Page 74: ...Master Control lever to 0 533RA193 TG 1 Machines with manual fuel pump Pull the fuel hose 1 off the stub arrow Pull off the carburetor and pull stub arrow out of fuel hose at the same time Check the c...

Page 75: ...f it drops there are three possible causes 1 The inlet needle is not sealing foreign matter in valve seat or sealing cone of inlet needle is damaged or inlet control lever sticking Remove to clean b 1...

Page 76: ...cover 1 so that the lever arrow is opposite the adjusting screws Fit the end cover 1 carefully the holes must be in alignment Insert the screws but do not tighten yet Check position of diaphragm and g...

Page 77: ...in the bore Position the inlet control lever 3 with spindle 2 on the spring s seat arrow first then slide the inlet control lever s clevis into the groove in the inlet needle 1 533RA309 TG 533RA310 T...

Page 78: ...taper arrow points towards the carburetor bore 1 533RA313 TG 1 533RA314 TG Take care to position the drift exactly to ensure that valve jet and carburetor bore are not damaged Fit the valve jet 1 in...

Page 79: ...atches the contour of the end cover arrows and is held in position by the pegs 2 Coat the diaphragm 1 with fuel and fit it so that it matches the contour of the gasket arrows and is held in position b...

Page 80: ...position air valve open about 10 1 It must be possible to move the air valve in both directions and it must always return to its starting position Lever 1 must butt against lever 2 and engage lever 3...

Page 81: ...ld the air valve shaft in the preloaded position Slide the air valve 1 with the hole 2 on the left and the marking visible into the slot in the shaft 533RA333 TG 1 1 533RA334 TG 533RA335 TG 2 1 Coat t...

Page 82: ...2 and replace if necessary Note installed position arrow of torsion spring 2 Clean the choke shaft and guides b 16 Install in the reverse sequence The throttle shaft is shown without the lever for re...

Page 83: ...eedom of movement Reassemble all other parts in the reverse sequence 2 533RA344 TG 3 1 2 1 533RA345 TG 14 4 8 Throttle Shaft Throttle Shutter Throttle shaft is stiff or throttle shutter cannot be clos...

Page 84: ...trainer 3 in the bore first Then fit the spring 2 and pump piston 1 in the bore arrow Push the throttle shaft 1 with torsion spring into the carburetor body from the side with the adjusting screws Use...

Page 85: ...row Attach the torsion spring to the lever arrow Fit the lever 1 and tighten the screw 2 slightly it must still be possible to turn the lever Turn the lever 1 clockwise until its arm can be fitted aga...

Page 86: ...djusting screws 533RA364 TG 2 1 533RA365 TG 2 1 3 The high speed screw H has a limiter cap which has to be removed before the screw is removed Always install a new limiter cap Remove the carburetor b...

Page 87: ...ts seat unscrew it one full turn counterclockwise this is the basic setting Screw down the low speed screw L 2 clockwise onto its seat With the low speed screw L 2 against its seat unscrew it one full...

Page 88: ...gine to warm up Turn low speed screw L counterclockwise until the engine runs and accelerates smoothly It is usually necessary to change the setting of the idle speed screw LA after every correction t...

Page 89: ...14 2 Remove the handle molding b 12 2 Disconnect the throttle rod 1 from the throttle trigger arrow Pull the throttle rod 1 out of its mount arrow Remove the throttle rod Check it and replace if nece...

Page 90: ...ws arrows Remove the intake manifold 1 Inspect the intake manifold 1 and replace if necessary even very minor damage can cause engine running problems b 4 6 Inspect and clean the sealing face arrow on...

Page 91: ...out of its seat arrow Check the shutter and replace it if necessary Install in the reverse sequence 1 533RA390 TG 1 533RA391 TG Coat the flanges of the intake manifold with STIHL Press Fluid b 16 To...

Page 92: ...ends of the strings with the manifold flanges arrows through the bores The manifold flanges are thus pulled through the carburetor carrier and into position without being damaged Position the fuel ho...

Page 93: ...Seal the fuel hose 1 with a plug arrow Vacuum test Push the ring 1 to the left and connect the pump 2 0000 850 1300 to the nipple arrow subject the fuel tank to a vacuum Equalization of pressure takes...

Page 94: ...1 4 Push the fuel hose 1 onto the stub arrow Reassemble all other parts in the reverse sequence Tightening torques b 3 5 14 8 3 Manual Fuel Pump Not installed in all machine versions A faulty manual f...

Page 95: ...e clogged with minute particles of dirt This restricts the passage of fuel and results in fuel starvation In the event of trouble with the fuel supply system always check the fuel tank and the pickup...

Page 96: ...ow in the fuel tank Line up the fuel hose 1 and press it into the housing bore until its flange is positioned as shown arrow and is flush with the housing Coat with STIHL Press Fluid b 16 1 2 3 533RA4...

Page 97: ...oses for the manual fuel pump are described in the chapter on manual fuel pump b 14 8 3 Remove the carburetor b 14 3 Remove the switch shaft b 12 1 Pull off the fuel hose 1 Remove the tank vent b 14 8...

Page 98: ...hose 1 onto the connector arrow Install the manual fuel pump if standard b 14 8 3 Reassemble all other parts in the reverse sequence Tightening torques b 3 5 533RA191 TG 1 14 9 4 Fuel Tank Cap See in...

Page 99: ...855 8106 Sealing the exhaust port 5 Flange 1123 855 4200 Sealing the exhaust port Hose for leakage test 1110 141 8600 Testing carburetor for leaks Nipple 0000 855 9200 Testing carburetor for leaks 6 P...

Page 100: ...r M8 5910 893 0501 Removing bar mounting studs 24 Installing tool 0000 890 2201 Installing rope guide bushing 25 Installing tool 1116 893 4800 Rewinding rewind spring 26 Hook 5910 893 8800 Removing pi...

Page 101: ...20 1109 High voltage output on ignition module 5 Dirko HT red sealant 0783 830 2000 Engine pan oil seals outside 5 Medium strength threadlocking adhesive Loctite 242 0786 111 2101 6 High strength thre...

Page 102: ...englisch english 0455 533 0123 M7 F7 FST Printed in Germany All manuals and user guides at all guides com...

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