Losi LST XXL User Manual - Manual (Page 3)

Page 3
Tools You Will Find Handy
In addition to the tools included with the LST XXL, you will find the following both useful and in some cases
necessary.
• Small flat blade and Phillips screwdrivers
• Needle-nose pliers
• Quality .050-inch, 1/16-inch, 5/64-inch, 3/32-inch, 1.5mm and 2.5mm hex (Allen) drivers
Engine Break-In and Adjustments
Breaking in your new engine is critical for proper performance. Failure to follow the break-in procedures can cause
damage and shortened engine life. During break-in and when running, always use Losi Nitrotane 20% Sport Fuel.
Although the carburetor is preadjusted at the factory, you must be familiar with the following adjustments and
break-in procedure. If you change fuel or run in dramatically different environments (hot/cold, high/low elevation,
etc.) you will probably have to adjust at least the high-speed needle to prevent overheating and maintain proper
performance. Never, under any circumstances allow the engine to rev freely with the wheels off the ground.
Break-In Procedure
1. The first three tanks of fuel should be run with the high and low speed needles noticeably “rich” (see
explanation below). There should be a slight sluggishness and thick smoke when accelerating with the
smoke decreasing as the model gains speed. At speed, there should still be a noticeable trail of smoke from
the exhaust pipe. Run the LST XXL on a flat surface in an oval pattern. Ease into the throttle as you accelerate
on the straight sections, easing off as you approach turns—letting the model roll through the turn before
easing back on the throttle. This will also allow you to get a feel for the steering response and handling
characteristics of the model.
2. You can also break in the engine by placing the model against a wall or fixed object and allowing the engine
to idle through two full tanks of fuel. You may have to lean the low-speed mixture (slightly) as noted below.
3. Note: The 2-speed will not shift during break-in. Do not expect the 2-speed to shift until at least the fifth or
sixth tank of fuel. If you want it to shift earlier follow the directions in “2-Speed Adjustment”.
Understanding “Rich” and “Lean” Fuel Mixture
Adjusting the carburetor is one of the most critical facets of running a nitro powered RC vehicle. The fuel mixture
is referred to as being “rich” when there is too much fuel and “lean” when there is not enough fuel for the amount
of air entering the engine. The amount of fuel entering the engine is adjusted with high- and low-speed threaded
needle valves. The low-speed needle is located in the front of the moving slide. The high-speed needle sticks
straight up at the back of the carburetor. Both feature a slotted head that is used as a reference and receptacle
for a flat blade screwdriver for adjustments. The mixture is made richer by turning the needle counterclockwise
and leaner by turning clockwise. An overly “rich” mixture will yield sluggish acceleration and performance with
thick smoke from the exhaust. A “lean” mixture can cause the engine to hesitate before accelerating or, in some
cases, to lose power momentarily after the initial acceleration. A lean mixture also makes the engine run hotter
than desired and does not provide enough lubrication for the internal engine components, causing premature
wear and damage. It is always advisable to run the engine slightly rich and never lean to avoid overheating and
possible damage.