Fuel - Stihl FS 500 Instruction Manual

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Mounting 225 and 250 Circular Saw
Blades
5
3
2
N Remove the grass shield and fit the
65 mm diameter thrust plate.
N Place the cutting attachment (1) in
position.
Collar (a) must locate in the
cutting attachment's mounting
hole (b).
The cutting edges of circular saw blades
must point clockwise.
N
Fit the 60 mm diameter thrust
washer (2) – convex side facing up.
N Fit the rider plate (3) for circular saw
blades or guard ring (5) for shredder
blade.
20
N Block the drive shaft.
N Screw on the nut (5)
counterclockwise and tighten it
down firmly.
Remove the tool used to block the
shaft.
Removing the cutting attachment
4
N Block the drive shaft.
N Loosen the mounting nut clockwise.
1
If the mounting nut has become
too loose, fit a new one.

Fuel

This engine is certified to operate on
unleaded gasoline and with the mix ratio
50:1.
Your engine requires a mixture of high-
quality premium gasoline and high-
quality two-stroke air-cooled engine oil.
Use premium branded unleaded
gasoline with a minimum octane rating
of 89 RON.
Note: Models equipped with a catalytic
converter require unleaded gasoline. A
few tankfuls of leaded gasoline can
reduce the efficiency of the catalytic
converter by more than 50%.
Fuel with a lower octane rating may
result in preignition (causing "pinging")
which is accompanied by an increase in
engine temperature. This, in turn,
increases the risk of the piston seizure
and damage to the engine.
The chemical composition of the fuel is
also important. Some fuel additives not
only detrimentally affect elastomers
(carburetor diaphragms, oil seals, fuel
lines etc.), but magnesium castings as
well. This could cause running problems
or even damage the engine. For this
reason it is essential that you use only
high-quality fuels!
Fuels with different percentages of
ethanol are being offered. Ethanol can
affect the running behaviour of the
engine and increase the risk of lean
seizure.
FS 500, FS 550