Harness
Adjusting the harness
N
Pull the ends of the straps
downward to tighten the harness.
N
Adjust the harness so that the
backplate fits snugly and securely
against your back.
Loosening the harness
N
Lift the tabs of the sliding adjusters.
SR 430, SR 450
Disconnecting harness from
backplate
1
N
Pull the ring (1) out of the slot.
Fuel
This engine is certified to operate on
unleaded gasoline and the STIHL two-
stroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of high-
quality gasoline and quality two-stroke
air cooled engine oil.
Use mid-grade unleaded gasoline with a
minimum octane rating of 89 (R+M/2). If
the octane rating of the mid-grade
gasoline in your area is lower, use
premium unleaded fuel.
Fuel with a lower octane rating may
increase engine temperatures. This, in
turn, increases the risk of 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 and
catalytic converters as well. This could
cause running problems or even
damage the engine. For this reason
STIHL recommends that you use only
nationally recognized high-quality
unleaded gasoline!
Use only STIHL two-stroke engine oil or
equivalent high-quality two-stroke
engine oils that are designed for use
only in air cooled two-cycle engines.
We recommend STIHL 50:1 two-stroke
engine oil since it is specially formulated
for use in STIHL engines.
Do not use BIA or TCW rated (two-
stroke water cooled) mix oils or other
mix oils that state they are for use in both
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