Stihl 5910 890 1700 Technical Information

STIHL Incorporated
Technical Information

New STIHL Engine Repair Tool Kit part number 5910 890 1700

The new STIHL Engine Repair Kit includes tools to
inspect and clean the cylinder components of all 2­stroke and 4-stroke cycle engines.

Components included in tool kit:

The main components of the kit include
various abrasive pads for cleaning gasket
surfaces, combustion chambers, valve seats,
and exhaust ports. A cylinder leak-down tester
is also included for checking exhaust and
intake valve sealing on all 4-stroke cycle
engines and also can be used to check piston
ring sealing and piston damage on all 2-stroke
cycle engines. Other useful tools are included
that are further explained in this bulletin. All of

the tools included in the kit are also available
separately (see summary on page 9).

When performing a cylinder leak down test
the flywheel must be blocked at TDC (top
dead center) to avoid rotation of the
crankshaft as high pressure air is introduced
into the cylinder. When using on 4-stroke
cycle engines, the piston should be at TDC
on the compression stroke with both valves
closed.

To use the cylinder leak down tester on
STIHL 4-Stroke engines, remove the valve
cover and index the crankshaft as pictured
below. Verify that the piston is at TDC on the
compression stroke and both intake and
exhaust valves are closed.

BR 500, BR 550, BR 600

STIHL Incorporated
Bulletin #DLR 2007-02

August 2, 2007

DLR 2007-02 New Special Tools ea 2012.doc Page 1 of 9

STIHL 4- Stroke Engine on Shafted
Products

Index arrow between flywheel fins with lower
ignition module mounting screw.

STIHL 4- Stroke Engine on Shafted
Products

Slide blocking tool down onto clutch housing.

Examples of the flywheel blocking tool used
with STIHL 4-MIX® engines:

STIHL 4-Stroke Engine on Shafted
Products

Insert the long pegs of the blocking tool down
between the flywheel fins.

BR 500, BR 550, BR 600

Insert the locating pin of the flywheel
blocking tool into the bolt hole referenced by
the top arrow and secure the tool to the boss
at the lower arrow with a 5 mm bolt normally
used to mount the starter assembly.

DLR 2007-02 New Special Tools ea 2012.doc Page 2 of 9

should now read zero. If not, adjust the
regulator until the right gauge is set to zero.
The gauge assembly is now ready to be
connected to the spark plug adapter hose.

BR 500, BR 550, BR 600

Flywheel blocking tool installed.
The cylinder leak down tester is capable of

verifying cylinder leakage in all 2-stroke and 4­stroke cycle engines. The hose on the tester
has a 14 mm diameter thread for conventional
spark plugs and and an adapter is included for
use in engines that utilize a 10 mm diameter
spark plug thread.

Cylinder Leak Down Tester Installation

To install the tester, thread the adapter hose
into the spark plug opening. Before connecting
the gauge assembly to the adapter hose, turn
the pressure regulator knob counterclockwise
until there is no tension on the regulator knob
(damage to pressure gauge can occur if the
regulator is not backed off before connecting
to air compressor).
Connect an air source of 90 PSI minimum to
the air inlet on the pressure regulator. Turn the
regulator clockwise until the needle on the left
gauge reaches the red set point at the 12
o’clock position, the needle on the right gauge

Above view of the tester showing cylinder
leakage of 75%.

The recommended leakage should not
exceed 10%. If so, the component at fault
will need to be determined (exhaust valve,
intake valve, piston rings, scored piston).
This can be determined by listening for any
escaping air at the intake port, exhaust port
or pushrod openings in cylinder head.

If the exhaust valve is leaking, STIHL
recommends using STIHL Engine De­Carbonizer fluid (part no. 0781 313 8019)
before disassembling the engine.

DLR 2007-02 New Special Tools ea 2012.doc Page 3 of 9

STIHL Engine De-Carbonizer is a mild
chemical solution that breaks down ash
deposits formed by low ash 2-cycle engine oils
and is ideal for removing deposits from
exhaust valves on mix lubricated 4-cycle
engines and softens combustion deposits in 2­cycle engines.

Procedure for using STIHL Engine De­Carbonizer:

• Move stop switch to the off position.

• Remove spark plug.

• Set piston to top dead center (on 4-stroke

engines: TDC between intake and exhaust
strokes at valve overlap with both valves
slightly open).

• Completely fill the combustion chamber
with STIHL Engine De-Carbonizer through
the spark plug opening and let stand for
approximately one hour. Do not leave the
liquid in the cylinder any longer than 12
hours. Note that the de-carbonizer fluid
works best and only needs to soak for
approximately 15 minutes if the engine can
be started and warmed up before applying
the chemical.

• Pour the de-carbonizer fluid out of the
spark plug opening onto an absorbent
towel. The solution can be disposed of in
normal trash collection and is not an
environmental hazard.

• Pull the starter rope several times to clear
the cylinder. On 4-cycle engines, ensure
that the valve clearance is set properly.

• Install the spark plug and start the engine.

• Note: the muffler spark arrestor screen

may need to be cleaned of loosened
combustion deposits after running the
engine.

In the event the de-carbonizer fluid does not
correct the problem, the engine will have to be
disassembled for further inspection and repair.

The tool kit also includes some specialized
tools including a 10 mm piston stop (part no.
4282 890 2700) designed for use with all
STIHL 4- Stroke engines. The piston stop is
used to block the crankshaft from rotating
when performing repairs.

Rotate the crankshaft until the piston
reaches BDC (bottom dead center). Thread
the piston stop into the spark plug hole until
fully seated.

Before the removal or installation of any
components, rotate the crankshaft in the
direction of the item to be removed or
installed until the piston contacts the stop.
Use the proper tools to remove or install the
desired part.

Important note: Do not use an air or electric
powered impact wrench to assemble or
disassemble components on any STIHL
product. Doing so will shear the flywheel key
and damage other components such as
clutches and crankshafts.

DLR 2007-02 New Special Tools ea 2012.doc Page 4 of 9

To further assist in disassembly, a flywheel
removal tool (part no. 1116 893 0800) is
included in the tool kit.

After the the piston stop has been installed
and the crankshaft blocked from movement,
remove the flywheel nut. Thread the puller
onto the crankshaft stub until contact with the
flywheel is made, now unscrew the puller ½
to 1 full turn.

While holding the flywheel, use a suitable tool
to tap the end of the puller to release the
flywheel.

Specialty abrasive pads are included in the
tool kit that greatly ease and reduce repair
times for cleaning gasket surfaces,
combustion chambers, valve seats, and
exhaust ports on any small engine.

DLR 2007-02 New Special Tools ea 2012.doc Page 5 of 9

The abrasive pads work ideally with a small
air powered right angle grinder. A standard
drill motor can also be used although a drill
is slower and requires a little more time to
clean the components.

The 2” abrasive disk is ideal for quickly and
easily cleaning away gasket sealant and
cleaning gasket surfaces. It is important to
use only light pressure when using this tool.
If excessive down pressure is used, the
abrasive disk will quickly wear and require
replacement.

The abrasive cleaning pads and disks have
several uses. Page 6 and 7 list some of the
applications and part numbers of the various
size pads and disks that are included in the
tool kit.

Abrasive Pads

for STIHL (and other) Engines



5910 893 1100 Long Mandrel



5910 893 5603 ¾” Abrasive Pad -



5910 893 5602 1” Abrasive Pad -





5910 893 1100 Long Mandrel



5910 893 5607 ¾” Abrasive Pad –



5910 893 5604 1” Abrasive Pad –



Excellent f or cleaning and polishing valve seats in
small 4-cycle engines.

• Use ¾” for all STIHL 4-MIX

(both intake and exhaust valve seats).

• Use ¾” for exhaust valve seat on STIHL 4-MIX®blowers

• Use 1” for intake valve seat on STIHL 4-MIX

Medium Grit (blue)

Medium Grit (blue)

Excellent for removing carbon deposits
from cylinder heads and exhaust ports.

• ¾” is ideal for cleaning cylinder heads
on STIHL 4-MIX
and small exhaust ports.

• 1” is ideal for cleaning cylinder heads
on all other STIHL engines.

®

shafted products

Extra Fine Grit (red)

Extra Fine Grit (red)

®

shafted products

®

blowers.

DLR 2007-02 New Special Tools ea 2012.doc Page 6 of 9

A setting gauge (part no. 4118 890 6401) is
included in the tool kit for setting the proper air
gap between the ignition module and flywheel.
The setting gauge can be used for all STIHL
4-Stroke

engines.

To use the setting gauge, install the ignition
module or, if the module is already in place,
loosen mounting screws. Rotate the flywheel
so the magnet poles are not interfering with
the ignition module armature and insert the
setting gauge.

Rotate the flywheel until the magnet poles
are between the setting gauge and the
ignition module armature legs. The magnets
will draw the ignition module tight against the
setting gauge. Tighten the mounting screws
to the recommended torque and remove the
setting gauge.

DLR 2007-02 New Special Tools ea 2012.doc Page 7 of 9

A 0.1 mm feeler gauge (part no. 4180 893

6400) is included in the tool kit. This gauge is
used for setting the proper valve clearance on
all STIHL 4- Stroke engines.

To set the valve clearance, rotate the
crankshaft to TDC (top dead center) and verify
that both valves are closed. There should be
play or movement in both the intake and
exhaust valve rocker arms.

Insert the feeler gauge between the rocker
arm and valve stem. Use an 8 mm wrench or
socket to tighten or loosen the adjusting nut
on top of the rocker arm (see arrow) until the
gauge is able to slide with some slight
resistance between the valve stem and rocker
arm.

The recommended valve clearance for all
STIHL 4- Stroke engines is 0.1 mm to 0.3 mm
(0.004” to 0.012”) when the engine is cold.

The tool kit also includes a lubricant that will
assist in the assembly of rubber
components such as intake manifolds, anti­vibration buffers, fuel hoses, and o-rings.
The lubricant evaporates after assembly
without leaving an oily residue.

DLR 2007-02 New Special Tools ea 2012.doc Page 8 of 9

Summary:

STIHL Engine Repair Tool Kit components and part numbers:

Description Part No. Remarks
STIHL Engine Repair Tool Kit 5910 890 1700

Includes:
Leak Down Tester 5910 850 0300

Flywheel Blocking Tool 5910 890 8600
Piston Stop 4282 890 2700 Replaces 4180 890 3400
Flywheel Puller 1116 893 0800

0.1 mm Feeler Gauge 4180 893 6400
Ignition Module Setting Gauge 4118 890 6401
Press Fluid Lubricant 0781 957 9000
Engine De-Carbonizing Fluid 0781 313 8019 1 bottle per kit
Reorder of 1=6 in a case

Mandrel for 2” Abrasive Disk 5910 890 0400
2” Abrasive Disk-Medium Grit 5910 893 5601 pkg. of 10

Long Mandrel for Abrasive Pads 5910 893 1100
1” Abrasive Pad- Medium Grit 5910 893 5602 pkg. of 10
¾” Abrasive Pad- Medium Grit 5910 893 5603 pkg. of 10
1” Abrasive Pad-Extra Fine Grit 5910 893 5604 pkg. of 10
¾” Abrasive Pad-Extra Fine Grit 5910 893 5607 pkg. of 10

DLR 2007-02 New Special Tools ea 2012.doc Page 9 of 9