Losi LOSR1002 User Manual

Owner’s Manual

Congratulations on the purchase your new Losi
product. Before installing your engine, please
read these instructions to ensure reliable and
trouble-free performance.

Using the Proper Fuel and Glow Plug

Using the proper fuel and glow plug is critical in order
to achieve maximum performance and reliability.
You must use fuel, glow plugs and air filters that
are specifically designed for model car/truck/buggy
applications. Never use any type of model airplane

glow fuel! Use of model airplane fuel can damage

your engine and immediately void any warranty.
We recommend using Losi Nitrotane™ fuel, providing

the best combination of power and fuel economy. Losi
fuels are vigorously tested, researched and formulated
to deliver excellent power as well as engine protection.

A glow plug has been included and is ideal for
breaking in your new engine. In fact, during the
break-in procedure, it is not uncommon to go through
one or two glow plugs, as microscopic bits of metal
(from the cylinder/piston wearing in) bond themselves
to the plug element causing glow plug failure. We
recommend the Dynamite McCoy MC59 Glow Plug
(DYN2508) as the absolute best glow plug for this
engine. The MC59 Plug has been designed to deliver
an ideal balance of performance and longevity.

All car engines must use a properly oiled air filter
to keep dirt out of the engine. Any dirt that enters
the carburetor can immediately destroy your engine.
We recommend LOSB5020 as an excellent choice
for a quality air cleaner. Service the air filter after
every hour of running, by washing out the foam filter
with warm water. Dry the filter then re-apply air filter
oil to the foam filter.

Carburetor Adjustments

Your Losi engine comes equipped with a precision
slide-valve carburetor. Take a moment to review the
pictures below to familiarize yourself with the various
functions of the carb. Loosening the nut located on the
side of the crankcase under the carburetor body will
allow you to rotate the carburetor to properly fit your
particular application. Make certain to mount the throttle
arm to the side required by your particular vehicle.
Although preset at the factory, some changes in the
needle setting can occur during shipping and handling.

High-Speed
Needle Valve

Low-Speed
Needle Valve

Fuel Inlet
(Adjustable)

Leaner

Fuel Inlet
(Adjustable)

Slower Idle
(counterclockwise)

Idle Stop
Adjustment

Low-Speed
Needle Valve

Faster Idle
(clockwise)

Leaner

We suggest the following settings for breaking in
your engine:

High-Speed Needle: 21/2 turns out (counterclockwise)

from closed.

1

Low-Speed Needle: 2

/2 turns out (counterclockwise)

from closed.

When checking the adjustment of the low­speed needle, it is crucial that the throttle
slide is closed completely when turning the
needle and that you do not over-tighten the
needle. Use an engine tuning screwdriver to
make this job easier. When you feel resistance
in the needle, immediately stop turning and
begin turning the needles counterclockwise,
counting the number of turns from “closed.”

Starting Your Engine

for the First Time

The first start of your engine is the most critical time of
the engine’s life, dictating how well it will perform. After
installing the engine in your model and inserting the
glow plug, turn on your radio system and attach a glow
igniter to the glow plug. Place your finger over over the
exhaust and turn the engine over with the starter for
2–3 seconds to prime the fuel line.(This should only be
necessary when the engine is cold, do not touch the

exhaust pipe when the engine is warm.) Should

the engine become difficult for ospin start to turn over,
the engine may be flooded (hydro-locked). Excess fuel
between the cylinder head and piston will not allow the
piston to travel through its full range of compression,
effectively “locking up” the engine. Should this occur,
immediately remove the glow igniter from the plug.
Using a glow plug wrench (LOSB4603), remove the
glow plug and turn the model upside down and rotate
the flywheel to clear out the fuel, re-install the glow plug
and start again.

You may need to “blip” the throttle on the transmitter
(applying throttle on/off) while trying to start the engine,
as new engines are more difficult to start due to the
tight piston/cylinder fit.

We recommend using an spin starter or starter box for
the initial starts, even with a pull-start equipped engine.
You may need to “blip” the throttle on the transmitter
(applying throttle on/off) while trying to start the engine,
as new engines are more difficult to start due to the
tight piston/cylinder fit.

Never start an engine above 1⁄4 throttle.
Immediate damage to your engine can
and will occur.

When the engine starts, the exhaust should emit lots
of blue/white smoke, indicating that the engine is
excessively rich (a good thing during break in). During
the first tank of fuel, you may wish to set a higher than
normal idle speed and/or leave the glow plug igniter
attached in order to keep the engine from stalling.
Drive your vehicle around while “blipping” the throttle
and avoid operating the engine at full throttle for
more than 2–3 seconds at a time. Consume the entire
first two tanks of fuel in this manner. After the first two
tanks of fuel, begin leaning out the high-speed needle
valve 1/8 turn at a time. It generally takes about 5
or 6 tanks of fuel before you’d want to start tuning
for “maximum” power.

Do not skip this process of breaking in a new
engine! Should you choose not to follow these
procedures, you risk damaging your engine
during the first tank of fuel.

Your patience during these procedures will be rewarded
by an engine that performs reliably and to its maximum
power potential. First run attempts can be more
frustrating than with other (less powerful) sport engines,
so take your time—it will be worth the wait. Glow
plug failure is a common occurrence when breaking
in a new engine. To test your plug, let the engine idle
at a properly adjusted low-speed needle setting with
the glow igniter attached. Then, remove the igniter. If
you hear no appreciable change in engine rpm, the
plug is still good. If the engine loads up and the rpm’s
decrease, it’s time to replace the glow plug.

Setting the Needle Valves

When tuning the needle valves for maximum
performance, adjust them in small increments,
1⁄16 turn at a time.

An engine should not be run too lean; doing so
severely shortens the life of the engine. When an
engine is set too lean, it will run very strong at
first but will soon begin to sag and hesitate or stall
when accelerating.

The best way to tune an engine is by using an
infrared temperature gauge, but you can also use
water to check the head temperature (refer to “Tuning
the High-Speed Needle”).

Tuning the High-Speed Needle

To obtain the correct high-speed needle setting, start
the engine and drive your vehicle around for a minute
or two, applying full throttle frequently. Place a drop
of water on the cylinder head. If the water sizzles away
(evaporates immediately), the needle setting is too
lean. A correct needle setting will result in the water
evaporating after 3–5 seconds. If the water does not
evaporate, chances are good that the needle setting is
too rich. Lean the needle 1/16 of a turn and run the
engine again, adjusting the needle setting to get the
desired evaporation time.

Check the temperature each time you change
the needle mixture. Do not let the engine
overheat, as this will damage the engine.

Tuning the Low-Speed Needle

The low-speed needle (also referred to as the idle
mixture or idle needle) should be set after you’re
satisfied with the high-speed needle setting. After
achieving the proper operating temperature, reduce the
engine throttle to idle and pinch the fuel line with your
fingers close to the carb fuel inlet nipple. If the engine
dies immediately, the low-speed needle is set too lean.
If the rpm’s increase dramatically, the setting is too rich.
The ideal setting results in the rpm’s increasing just a
slight amount after pinching the fuel line.

Idle Stop Adjustment

The last setting to be made is the idle stop screw.
Turning this screw clockwise increases the idle speed,
whereas turning the screw counterclockwise will
make the engine idle at a lower speed. Ideally, the
engine should idle just fast enough to be reliable in
acceleration and transition from idle to full speed.
Avoid an idle speed that is too fast, as it will cause
damage to your clutch.

After Operating Your Engine

Periodic maintenance must be performed in order
to keep your engine in proper operating condition.
After each day of running, it’s critical to use high
quality after-run oil to protect the internals of the
engine and help prevent corrosion. (This is not
necessary when using Losi fuels.) The methanol
used in the fuel attracts moisture that can cause
corrosion (particularly in the ball bearings). Follow
these steps after running your engine:

1) Empty all fuel from the tank and fuel lines.

2) Remove the glow plug and air filter and add
5 to 6 drops of a quality after-run oil into the
carburetor and cylinder head openings. Turn
the engine over a few times to distribute the oil
throughout the engine.

3) Clean and inspect the engine, air cleaner and
fuel system.

Problem

Engine won’t start

Engine starts, then dies

Engine starts and runs
for 1⁄2 tank, then quits

Troubleshooting Guide

Possible Cause/Solution

• Clogged fuel line

• Bad or improper glow
plug

• Glow igniter not
charged

• Bad or old fuel

• Glow plug is bad

• Engine flooded

• Pressure line blocked or
disconnected

• Bad glow plug

• High-speed needle too
lean

• Hole or tear in fuel line

• Bad glow plug or idle
speed set too low

• Overheated engine
(too lean)

• Improper needle
settings