STIHL 4-Stroke Engine Check
©2010 STIHL Incorporated
1. Check condition of cutting attachment or blower
tube and nozzle. 10. Set valve clearance to
0.1 mm (0.004”) when
cold. 0.1 to 0.3 mm
(0.004” to 0.012”) is
acceptable.
2. Check throttle for proper operation, opens 11. Perform cylinder leak
completely, returns to idle. down test. Maximum
of 10% leakage is
3. Empty fuel tank: check for debris, acceptable.
contamination, and verify if oil is mixed.
Warning! Gasoline is extremely flammable.
Keep away from spark or other ignition source.
Properly dispose of fuel per local regulations. 12. Install valve cover and new gasket. Install
spark plug; perform crankcase pressure and
4. Inspect spark plug connector and high tension vacuum test.
lead.
5. Check for spark with a ZAT 4 tester with plug
Pressure specification:
installed, if no spark retest with new plug.
Pressurize to 0.5 bar (7
Verify stop switch function.
psi). Leakage to 0.3 bar
(4 psi) in 20 seconds is
6. Verify that spark plug is correct heat range and
acceptable.
set electrode gap to .020” (0.5 mm).
FS 90, FS 100, FS 110, FS 130, KM 130,
KM 110, HL 100, HT 130, HT 131,
FC 100, FC 110, BR 500, BR 550, BR 600
HT 100, HT 101 Vacuum specification:
STIHL 0000 400 7009 Apply vacuum of -0.5
STIHL 0000 400 7011
Bosch USR7AC bar (-7 psi). Leakage to
NGK CMR6H
NGK CMR5H -0.3 bar (-4 psi) in 20
seconds is acceptable.
7. Remove shroud, loosen muffler and inspect fire
screen, inspect air filter, remove carburetor.
8. Check for sheared flywheel key by verifying 13. Verify impulse signal
flywheel is in time with crankshaft (note flywheel Connect a second
markings in relation to ignition armature when piston gauge to impulse hose
is positioned at top dead center). while performing
pressure and vacuum
tests. Gauge needle
should move while
performing tests.
9. Verify proper air gap between ignition module
and flywheel. Use tool 4118 890 6401.
14. Perform carburetor check-shafted products:
Step 1: Attach tester
to fuel supply fitting.
Pressurize carburetor
to 0.7 bar (10 psi). If
pressure holds, the
fuel pump components
and inlet needle are
sealing. Go to step 2. Step 3: Attach tester to primer return hose. Push
primer bulb; gauge should indicate pressure and
Step 2: With pressure
hold. If not, purge primer is faulty.
present from step 1,
pump primer bulb and the
15. Pressure test tank to 0.3 bar (5 psi). There
gauge needle should go
should be no leakage
down. Put tester in
vacuum mode and pump
16. Vacuum test tank, it should slowly leak back
bulb 3 times and the
to atmospheric pressure. If not, tank vent is
needle should show a
faulty.
vacuum for a minimum of
1 second. If not,
17. Inspect or replace fuel filter. Important: use
carburetor has an internal
only STIHL filter part no. 0000 350 3502.
leak.
Step 3: Attach tester to
return line fitting in
pressure mode. Pump
primer bulb and gauge
should indicate pressure
and hold. If not, purge
primer flange is faulty. Replace Okay New
14. Perform carburetor check-backpack blowers:
18. Pressure test fuel lines to 0.3 bar (5 psi).
There should be no leakage
19. Perform necessary repairs and re-assemble.
20. Set the carb H and L screws with limiter cap
removed to initial start-up setting of H = 3
Step 1: Attach tester to fuel line fitting. Pressurize turns out from lightly seated, L = 2 turns out
carburetor to 0.7 bar (10 psi). If pressure holds, the from lightly seated (refer to repair
fuel pump components and inlet needle are specification charts for detailed settings).
sealing. Go to step 2. Final adjustment may vary significantly.
21. Verify throttle cable adjustment.
22. Start engine, warm up and perform final
carburetor adjustments. Verify idle speed and
maximum RPM (refer to repair specification
charts). Seat limiter caps in place.
Step 2: With pressure present from step 1, pump 23. Test run machine under load.
primer bulb and the gauge needle should go down.
Put tester in vacuum mode and pump bulb 3 times 24. Verify stop switch function.
and the needle should show a vacuum for a
minimum of 1 second. If not, carburetor has an Checklist complete.
internal leak.
