Losi LOSB0020 - Manual (Page 4)

Base Start-up Settings from the Factory
High Speed Needle—2
3 /
4
turns out from bottom
Low Speed Needle—3 turns out from bottom
Engine Tuning
After the engine is broken in, you can tune it for optimum
performance. When tuning, it is critical that you be cautious of
overheating as severe damage and premature wear can occur. You
want to make all carburetor adjustments in “one hour” increments.
Low Speed Adjustment
The low speed adjustment affects the idle and slightly off idle
performance. The optimum setting allows the motor to idle for at least
8−10 seconds. The model should then accelerate with a slight amount
of sluggishness and a noticeable amount of smoke. The simplest way
to check this is to make sure the engine has been warmed up and let
the engine idle for 8−10 seconds. If the low speed mixture is so far off
that the engine won’t stay running this long, turn the idle stop screw
clockwise, increasing the idle speed. With the engine at idle, pinch
and hold the fuel line near the carburetor, cutting off the flow of fuel, and listen closely to the engine
rpm (speed). If the low speed needle is set correctly, the engine speed will increase only slightly and
then die. If the engine increases several hundred rpm before stopping, the low speed needle is too rich.
Lean the mixture by turning the needle clockwise one hour and trying again. If the engine speed does
not increase but simply dies, the needle is too lean and needs to be richened up by turning the needle
counterclockwise one hour before trying again. After you have optimized the low speed setting, the
engine will probably be idling faster. You will have to adjust the idle stop screw counterclockwise to slow
down the engine idle speed. The engine should accelerate at a constant pace without hesitating.
Page 4
1 H
our
2 H
our
Carb Adjustments:
Make all carburetor adjustments in one
hour increments. Imagine the slot in
the needle is the hour hand on a clock.
Adjust it as though you were moving
the hour hand from one hour to the
next or previous one.
High speed Needle
As you turn this clockwise
(leaner), less fuel enters
the engine. Turning it
counterclockwise (richer)
allows more fuel to enter
the engine.
Low speed Needle
As you turn this clockwise
(leaner), less fuel enters
the engine. Turning it
counterclockwise (richer)
allows more fuel to enter
the engine.
Idle Speed Screw
As you turn this clockwise,
it increases the carburetor
opening at idle and increases
idle speed. Turning it
counterclockwise decreases
the opening and idle speed.
High speed
Needle
Idle Speed
Needle
Low speed
Needle
Carb Opening
Richer
Richer
Slower
Leaner
Leaner
Faster