Stihl BR 800 Service Manual
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Stihl BR 800 Service Manual

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STIHL BR 800
Service Manual
2018-06

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Summary of Contents for Stihl BR 800

  • Page 1 STIHL BR 800 Service Manual 2018-06...

  • Page 3: Table Of Contents

    Ignition System 6.11 Installing the Spring Housing 13.1 Special Servicing Tools, Servicing Aids 6.12 Tensioning the Rewind Spring. This service manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process with electronic systems. BR 800...
  • Page 4 Installing Cam Followers and Cam Gear 18.6 Installing Rocker Arms and Pushrods Testing Engine for Leaks 19.1 Tools, Servicing Aids 19.2 Testing Compression Pressure 19.3 Testing Engine for Leaks Crankcase, Crankshaft, Oil Seals 20.1 Tools, Servicing Aids 20.2 Removing the Collar Studs BR 800...

  • Page 5: About This Service Manual

    If there is a risk of particles being thrown during the repair: Wear safety glasses. Spare Parts If spare parts not approved by STIHL are installed, they may not fulfill the required function or deactivate safety devices. This can result in serious or fatal injuries.

  • Page 6: Troubleshooting

    Fit new spring on rope rotor, @ 6.6. Go to 2. fatigued? Go to 2. Are pawls on the rope rotor damaged Fit new pawls on rope rotor, @ 6.6. Replace rewind starter, @ 6.2. or badly worn? Repair completed. Repair completed. BR 800...

  • Page 7: Starter Rope Is Difficult To Pull Or Rewinds Very

    12. Is connector of wiring harness’ black Go to 13. Push connector of wiring harness’ wire firmly seated? black wire firmly into place, @ 14.3. Go to 13. 13. Is ignition lead chafed? Replace ignition lead, @ 13.5. Go to 14. Go to 14. BR 800...

  • Page 8: Engine Will Not Idle, Idle Speed Too High

    Test tank vent, @ 10.4. Go to 6. Fit new tank vent, @ 10.7. Is tank vent OK? Go to 6. Is fuel system leaking? Replace fuel hoses, @ 8.2. Replace carburetor, @ 8.2. Repair completed. Repair completed. BR 800...

  • Page 9: Engine Does Not Start Easily, Stalls At Idle

    @ 20.6. Go to 11. 11. Are air inlets in blower housing Clean all cooling air inlets, pre-sep- Go to 12. blocked, is pre-separator plugged or arator and cylinder fins are cylinder fins very dirty? Go to 12. BR 800...

  • Page 10: Engine Speed Drops Quickly Under Load - Low

    Test tank vent, @ 10.4. Go to 6. Fit new tank vent, @ 10.7. Is tank vent OK? Go to 6. Is pickup body in oil tank dirty? Replace pickup body in fuel tank, @ Go to 7. 10.2. Go to 7. BR 800...

  • Page 11: No Spark

    @ 15.3, @ 8.3. Go to 9. Is ignition lead chafed? Install new ignition module, @ 13.5. Go to 10. Go to 10. 10. Is flywheel damaged? Replace flywheel, @ 13.3. Go to 11. Go to 11. BR 800...

  • Page 12: Engine Does Not Start

    @ 14.6, piston rings or oil seals, Is engine OK? @ 20.4 or seal up or replace crank- case, @ 20.5. Go to 12. 12. Does condition still exist? Replace carburetor, @ 8.2. Repair completed. Repair completed. BR 800...

  • Page 13: Engine Does Not Reach Maximum Rpm

    @ 20.4 or seal up or replace crank- case, @ 20.5. Go to 6. Is fuel system leaking? Replace fuel hoses, @ 8.2. Go to 7. Go to 7. Is maximum engine speed higher that Repair completed. Replace carburetor, @ 8.2. 8,300 RPM Repair completed. BR 800...

  • Page 14: Harness

    Rotate the lower sliding adjusters of the harness straps (1 and 5) through 90° and push them out through the openings in the backplate. Take out the screws (4). Remove the straps (1 and 5). Take out the screws (3). Remove the waist belt (2). BR 800...

  • Page 15: Fitting The Harness

    Engage the upper sliding adjusters, @ 5.3. Fitting the Backplate Extension Preparations, @ 3.1. Disengage the upper sliding adjusters, @ 5.2. Place the backplate (6) in position. Insert and tighten down the screws (7) firmly. Engage the upper sliding adjusters, @ 5.3. BR 800...

  • Page 16: Rewind Starter

    – STIHL gear grease – 0781 417 1315 Hold the rope rotor (13) steady. – STIHL OH 723 press fluid – 0781 957 9000 Pull out the starter grip (2) until the starter rope (3) is – under tension. Removing the Rewind Starter...

  • Page 17: Removing The Rewind Spring

    Pull the knot (25) out of the rope rotor (13). The rewind spring can pop out and cause serious eye and hand injuries. Wear safety glasses and work gloves. Undo the knot (25). Unlock and remove the cap (1). BR 800...

  • Page 18: Installing The Rope Rotor

    Push the spring (14) into the guides (arrows). Push the spring housing (17) onto the starter post. WARNING The rewind spring can pop out and cause serious eye and hand injuries. Wear safety glasses and work gloves. Install the rewind spring, @ 6.9. BR 800...

  • Page 19: Tensioning The Rewind Spring

    Fit the spring (22) so that the lobes of the pawls (23) are inside the spring (22). Push the spring (22) into the guides (arrows). Fit bearing shell (24) in the starter cover (9) and engage it in position. Install the rewind starter, @ 6.14. BR 800...

  • Page 20: Installing The Rewind Starter

    (9). 6.16 Installing the Stop Buffers Coat cones of stop buffers (8) with press fluid. Press the stop buffers (8) into the openings in the starter cover (9). Install the rewind starter, @ 6.14. BR 800...

  • Page 21: Air Filter, Shroud

    (3). Insert and tighten down the screws (1). Removing the Shroud Preparations, @ 3.1. Remove the rewind starter, @ 6.2. Remove the filter cover (2), @ 7.2. Unscrew the screw (8) and remove it with the cover (7). BR 800...

  • Page 22: Filter Housing, Carburetor, Fuel Pump

    – Pry out the grommet (8). Flat nose side cutting pliers – Installing Filter Housing and Carburetor STIHL OH 723 press fluid – 0781 957 9000 – Removing Filter Housing and Carburetor Fit the grommet (8). Insert the gasket (5).

  • Page 23: Removing The Fuel Pump

    Fit the filter cover, @ 7.3. Removing the Fuel Pump Preparations, @ 3.1. Remove filter housing and carburetor, @ 8.2. Pull off the fuel hose (12) to the carburetor (7). Unlock retaining lugs of fuel pump (5) and remove the fuel pump (5). BR 800...

  • Page 24: Installing The Fuel Pump

    The following tightening sequence of screws (1) and (2) must be observed to make sure the baffle (10) is properly sealed after installation and the carburetor (7) is correctly fitted, @ 8.3. Install the filter housing and carburetor, @ 8.3. BR 800...

  • Page 25: Carburetor

    Fit nipple 0000 855 9201 (45) in the 135mm Pin punch, 6 mm – hose 1110 141 8600 (46). STIHL OH 723 press fluid – 0781 957 9000 – Connect hose from pump 0000 850 1300 (43) to Loctite 242 (medium-strength threadlocking nipple 0000 855 9201 (45).

  • Page 26: Disassembling The Carburetor

    9.3.8 Removing the Choke Shaft Take out the screw (21). Remove the choke shutter (20). Take out the screw (11). Pull off the choke knob (37). The spring (12) may pop out. Take out the screw (35). Pull out the clip (34). BR 800...

  • Page 27: Assembling The Carburetor

    Fit the spring (39) on the throttle shaft (38) so that its bent end (arrow) engages the lever on the throttle shaft (38). Push the bushing (40) onto the throttle shaft (38). Push the sealing ring (42) into the ring (41). BR 800...
  • Page 28 Press the inlet control lever (14) down and hold it throttle lever (27). there. Fit E-clip (28) in groove of pin (24). Insert and tighten down the screw (11). Push the sealing ring (31) into the ring (30). BR 800...

  • Page 29: Adjusting The Carburetor

    Adjust engine speeds with the aid of the EDT 8 used at temperatures below –10°C. The carburetor can be tachometer 5910 850 1009 or MDG 1 analyzer adjusted to obtain normal engine acceleration in such 5910 840 0210 (tolerance ± 200 rpm). conditions. BR 800...
  • Page 30 Rotate the low speed screw (L) a quarter turn counterclockwise. If the engine stalls: Adjust idle speed. Engine power may drop noticeably when the blower is subsequently used at temperatures above –10°C. Carry out the standard setting. BR 800...

  • Page 31: 10 Backplate, Tank Housing

    – Screwdriver, T27x200 – 5910 890 2415 or equivalent – Hook – 5901 893 8800 – STIHL OH 723 press fluid – 0781 957 9000 – 10.2 Removing Pickup Body from Fuel Tank Preparations, @ 3.1. Open the tank cap (9).

  • Page 32: Removing The Fuel Tank

    Remove the backplate (1). 10.10 Removing the Protective Screen Preparations, @ 3.1. Remove the backplate, @ 10.9. Unlock retaining lugs of protective screen (14) and Do not remove the two hoses from the connector (12). remove the protective screen (14). BR 800...

  • Page 33: 10.11 Fitting The Protective Screen

    Lay down the backplate (4) on its flat side. Position the powerhead/blower unit on the backplate (4) so that the antivibration elements (arrows) locate in their seats in the backplate (4). Insert and tighten down the screw (5). Stand the backplate (4) with powerhead/blower unit upright. BR 800...

  • Page 34: 11 Antivibration Elements

    Screw the bearing plug (4) clockwise onto the Pipe wrench – spring (5) as far as stop. STIHL OH 723 press fluid – 0781 957 9000 – If the springs and bearing plugs cannot be fitted by hand: Coat guides in bearing plugs with press fluid.

  • Page 35: Installing The Stop Buffer

    11.5 Installing the Stop Buffer Coat the stop buffer (7) with press fluid. Push the stop buffer (7) into the bore as far as stop. Install the backplate, @ 10.12. Install the tank housing, @ 10.6. BR 800...

  • Page 36: 12 Adjusting Valve Clearance

    Turn the flywheel (9) one more revolution. Remove the spark plug (1). Unscrew the screw (3) and remove it with the cover (2). Take out the screw (4). Remove the sealing ring (5). Remove the valve cover (6). Remove the gasket (7). BR 800...
  • Page 37 Push the sealing ring (5) onto the thread of screw (4). Insert and tighten down the screw (4). Install the spark plug (1). Fit the cover (2) together with screw (3). Insert and tighten down the screw (3). Install the rewind starter, @ 6.14. BR 800...

  • Page 38: 13 Ignition System

    – 13.2.1 Testing Ignition Spark with ZAT 4 Ignition Tester Soft-faced hammer – Preparations, @ 3.1. STIHL OH 723 press fluid – 0781 957 9000 – Remove the cover, @ 7.3. Pull boot (9) off the spark plug. 13.2 Testing the Ignition System WARNING The saw’s ignition system generates high voltages.

  • Page 39: Removing The Flywheel

    (arrow) engages the slot (arrow) in the crankshaft. Remove the cover, @ 7.4. Rotate the flywheel (1) clockwise by hand as far as Pull boot (9) off the spark plug. stop. Check spark plug (10) and replace if necessary. The piston is now blocked. BR 800...

  • Page 40: Removing The Ignition Module

    Use a needle to pierce the center of the ignition lead’s insulation at distance ‘a’ = 10 mm (0.4 in) from the end of the lead (7). Pinch the hook of the leg spring (8) into the pierced hole in the ignition lead (7) as far as stop. BR 800...

  • Page 41: 14 Airflow Shroud, Impulse Hose, Manifold

    Screwdriver, T27x200 – 5910 890 2415 or equivalent – Punch-down tool – 5910 890 4000 – Flat nose side cutting pliers – STIHL OH 723 press fluid – 0781 957 9000 – 14.2 Removing the Airflow Shroud Preparations, @ 3.1. Remove the filter cover, @ 7.2.

  • Page 42: Removing The Impulse Hose

    Tighten down the screw in the hose clamp (4). Remove the manifold (3) with hose clamp (4) and flange (2). Pull the sleeve (1) out of the manifold (3). Pull manifold (3) out of the flange (2). Remove the hose clamp (4) from the manifold (3). BR 800...

  • Page 43: 15 Control Handle

    Unlock retaining lugs of setting lever (1) and take out Punch-down tool – 5910 890 4000 – the setting lever (1). Flat nose side cutting pliers – STIHL multipurpose grease – 0781 120 1110 15.3 Fitting the Control Handle – 15.2 Removing the Control Handle Lubricate opening for setting lever (1) in handle (2) with STIHL multipurpose grease 0781 120 1110.
  • Page 44 2. Yellow wire (11) so that it engages the lockout lever (8). 3. Bowden cable Lubricate web (19) in handle molding (2) with STIHL multipurpose grease 0781 120 1110. Push blade receptacle of black wire onto the contact spring (11) so that its closed side faces the contact spring (11).

  • Page 45: Removing The Clamp

    @ 14.3. Connect throttle cable to carburetor, @ 8.3. Install wiring harness on engine, @ 8.3. Push the sleeve (13) onto the throttle cable (12). Push the sleeve (13) into the retainer. Install the control handle, @ 15.3. BR 800...

  • Page 46: 16 Muffler

    Fit new muffler gasket (1) on the screw threads. Install the rewind starter, @ 6.14. Place the muffler (2) in position. Install the cover, @ 7.5. Insert and tighten down the screws (3) firmly. Install the shroud, @ 16.2. BR 800...

  • Page 47: 17 Blower Assembly

    Screwdriver, T27x200 – 5910 890 2415 or equivalent – If necessary: Remove the pleated hose together with Socket, 18 mm – the blower tube. STIHL OH 723 press fluid – 0781 957 9000 – If necessary: Remove the antivibration elements, @ 11.2. 17.2 Removing the Stop Buffer 17.5...

  • Page 48: Removing The Inner Blower Housing

    Screw home the screws (10) as far as stop. Tighten down the screws (10) to 1.5 Nm. Then turn screws (10) back one full turn. Install the backplate, @ 10.12. Fit the pleated hose together with the blower tube. Install the control handle, @ 15.3. BR 800...

  • Page 49: 18 Valve Gear

    Top dead center on ignition stroke can be set only with the valve gear installed. Remove the rocker arms (9). Set the crankshaft to top dead center on ignition stroke Pull out the pushrods (8). before removing the valve gear. BR 800...

  • Page 50: Removing Cam Followers And Cam Gear

    Fit the sleeves (10). Fit locknuts (11) on the collar studs. Check that the ends of the pushrods (8) are seated in the cam followers (3 and 4). Check lever (arrow) of decompression system to make sure the following points apply: BR 800...
  • Page 51 Insert and tighten down the screws (1). If the inner blower housing has been removed: Install inner blower housing, @ 17.7. Install the blower wheel, @ 17.8. Install outer blower housing, @ 17.9. Adjust valve clearance, @ 12.2. Install the cover, @ 7.5. BR 800...

  • Page 52: 19 Testing Engine For Leaks

    Hold the ZAT 3 only by the handle (3) during the test. Loosen screws on muffler (12), @ 16.2. Slide the sealing plate 0000 855 8106 (11) between the exhaust port and muffler (12) so that it completely fills the space between the two screws. BR 800...
  • Page 53 Take out the screws (8). Remove the test flange 5910 850 4200 (9). Remove the muffler (12), @ 16.2. Remove the sealing plate 0000 855 8106 (11). Fit a new muffler gasket, @ 16.3. Install the muffler (12), @ 16.3. BR 800...

  • Page 54: 20 Crankcase, Crankshaft, Oil Seals

    – Install the spark plug (1). Punch-down tool – 5910 890 4000 – Install the cover, @ 7.4. STIHL multipurpose grease – 0781 120 1110 – HT red silicone sealant – 0783 830 2000 – 20.4 Removing the Engine Pan and Oil Seals Loctite 270 (high-strength threadlocking adhesive) –...
  • Page 55 (17). Lift away the piston (13). Remove piston rings (15 and 16). If the piston rings (15 and 16) are damaged: Replace the piston rings (15 and 16). The snap ring (14) need not be removed. BR 800...
  • Page 56 20.11. NOTICE The diameter of the intake valve (7) is larger than that of the exhaust valve (6). Fit intake valve (7) in intake side of cylinder (5). Fit exhaust valve (6) in exhaust side of cylinder (5). BR 800...
  • Page 57 Install the blower wheel, @ 17.8. Install outer blower housing and elbow, @ 17.9. Install the backplate, @ 10.12. Install the airflow shroud, @ 14.3. Install the filter housing and carburetor, @ 8.3. Install the air filter, @ 7.3. BR 800...
  • Page 58 Socket, 13 mm, long, or equivalent Removing the flywheel 5910 893 6400 Feeler gauge Checking, adjusting valve clearance 5910 893 8800 Hook Installing the pickup body Socket, 16 mm, long Removing, installing spark plug Socket, 18 mm Removing, installing blower wheel BR 800...
  • Page 59 0781 417 1315 STIHL special lubricant Installing the rewind spring 0781 957 9000 STIHL OH 723 press fluid Installing rubber components; installing manifold 0783 830 2000 Silicone sealant, HT red Installing valve gear; installing engine pan...
  • Page 60 RA_014_2018_01_01 englisch www.stihl.com...

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