Losi LOSB0012 User Manual - Manual (Page 4)

Page 3
Base Start-up Settings from the factory
High-Speed Needle -- 3 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.
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.
Low Speed Adjustment
The low speed adjustment effects the idle and slightly off idle performance.
The optimum setting allows the motor to idle for at least 8-10 seconds. The truck
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 mix-
ture 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 to 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 to
lean and needs to be richened up by turning the needle counter-clockwise 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
counter-clockwise to slow down the engine idle speed. The engine should accelerate at a constant pace without
hesitating.
High-Speed Needle
As you turn this clockwise(leaner)
less fuel enters the engine.
Turning it counter-clockwise
(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 counter-clockwise
decreases the opening and idle
speed.
Low Speed Needle
As you turn this clockwise(leaner)
less fuel enters the engine.
Turning it counter-clockwise
(richer) allows more fuel to enter
the engine.
Richer Leaner
Idle Speed
Screw
Faster Slower
Hi-Speed
Needle
Carb Opening
Leaner Richer
Low-Speed
Needle