Losi LOSR2100 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.

glow fuel!

your engine and immediately void any warranty.
We recommend using Losi Nitrotane

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 DYN2495 Glow Plug as this
is the best glow plug for this engine. The DYN2495
Plug has been designed to deliver an ideal balance of
performance and longevity.

Never use any type of model airplane

Use of model airplane fuel can damage

™

fuel, providing

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

Faster Idle

Slower Idle

(clockwise)

(counterclockwise)

Idle Stop
Adjustment

Leaner

Fuel Inlet
(Adjustable)

We suggest the following settings for breaking in
your engine using Nitrotane 20% Sport Fuel.

Low-Speed
Needle Valve

High-Speed Needle: 23/4 turns out (counterclockwise)

from closed.

3

Low-Speed Needle: 2

/4 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
(LOSA99176) 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,

the exhaust pipe when the engine is warm.

Should the engine become difficult for the spin 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.

do not touch

)

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. If the engine dies when throttle is
applied the plug may be bad. Remove the plug and
attach the igniter and check for a bright glow. If all the
coils are not glowing it should be replaced. If the new
plug exhibits the same behavior the needle setting is
probably too rich and should be adjusted.

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 (LOSA99171), 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. 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.

Troubleshooting Guide

Problem

Engine won’t start

Engine starts, then dies

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

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

Warranty Period:

Exclusive Warranty- Horizon Hobby, Inc., (Horizon)
warranties that the Products purchased (the “Product”)
will be free from defects in materials and workmanship
at the date of purchase by the Purchaser.

Limited Warranty

(a) This warranty is limited to the original Purchaser
(“Purchaser”) and is not transferable. REPAIR OR
REPLACEMENT AS PROVIDED UNDER THIS
WARRANTY IS THE EXCLUSIVE REMEDY OF THE
PURCHASER. This warranty covers only those Products
purchased from an authorized Horizon dealer. Third
party transactions are not covered by this warranty.
Proof of purchase is required for warranty claims.
Further, Horizon reserves the right to change or modify
this warranty without notice and disclaims all other
warranties, express or implied.

(b) Limitations- HORIZON MAKES NO WARRANTY
OR REPRESENTATION, EXPRESS OR IMPLIED,
ABOUT NON-INFRINGEMENT, MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE OF THE
PRODUCT. THE PURCHASER ACKNOWLEDGES
THAT THEY ALONE HAVE DETERMINED THAT THE
PRODUCT WILL SUITABLY MEET THE

REQUIREMENTS OF THE PURCHASER’S INTENDED
USE.

(c) Purchaser Remedy- Horizon’s sole obligation
hereunder shall be that Horizon will, at its option,
(i) repair or (ii) replace, any Product determined by
Horizon to be defective. In the event of a defect, these
are the Purchaser’s exclusive remedies. Horizon
reserves the right to inspect any and all equipment
involved in a warranty claim. Repair or replacement
decisions are at the sole discretion of Horizon.
This warranty does not cover cosmetic damage or
damage due to acts of God, accident, misuse, abuse,
negligence, commercial use, or modification of or
to any part of the Product. This warranty does not
cover damage due to improper installation, operation,
maintenance, or attempted repair by anyone other than
Horizon. Return of any goods by Purchaser must be
approved in writing by Horizon before shipment.

Damage Limits:

HORIZON SHALL NOT BE LIABLE FOR SPECIAL,
INDIRECT OR CONSEQUENTIAL DAMAGES, LOSS OF
PROFITS OR PRODUCTION OR COMMERCIAL LOSS
IN ANY WAY CONNECTED WITH THE PRODUCT,
WHETHER SUCH CLAIM IS BASED IN CONTRACT,
WARRANTY, NEGLIGENCE, OR STRICT LIABILITY.
Further, in no event shall the liability of Horizon exceed
the individual price of the Product on which liability is
asserted. As Horizon has no control over use, setup,
final assembly, modification or misuse, no liability shall
be assumed nor accepted for any resulting damage or
injury. By the act of use, setup or assembly, the user
accepts all resulting liability.

If you as the Purchaser or user are not prepared to
accept the liability associated with the use of this
Product, you are advised to return this Product
immediately in new and unused condition to the place
of purchase.

Law: These Terms are governed by Illinois law (without
regard to conflict of law principals).

Safety Precautions:

This is a sophisticated hobby Product and not a toy.
It must be operated with caution and common sense
and requires some basic mechanical ability. Failure to
operate this Product in a safe and responsible manner
could result in injury or damage to the Product or
other property. This Product is not intended for use by
children without direct adult supervision. The Product
manual contains instructions for safety, operation
and maintenance. It is essential to read and follow all
the instructions and warnings in the manual, prior to
assembly, setup or use, in order to operate correctly
and avoid damage or injury.

Questions, Assistance, and Repairs:

Your local hobby store and/or place of purchase
cannot provide warranty support or repair. Once
assembly, setup or use of the Product has been started,
you must contact Horizon directly. This will enable
Horizon to better answer your questions and service
you in the event that you may need any assistance.
For questions or assistance, please direct your

email to [e-mail], or call

877.504.0233 toll free to speak to a service technician.

Inspection or Repairs

If this Product needs to be inspected or repaired, please
call for a Return Merchandise Authorization (RMA).
Pack the Product securely using a shipping carton.
Please note that original boxes may be included, but
are not designed to withstand the rigors of shipping
without additional protection. Ship via a carrier that
provides tracking and insurance for lost or damaged
parcels, as Horizon is not responsible for merchandise
until it arrives and is accepted at our facility. A Service
Repair Request is available at www.horizonhobby.com
on the “Support” tab. If you do not have internet access,
please include a letter with your complete name, street
address, email address and phone number where
you can be reached during business days, your RMA
number, a list of the included items, method of payment
for any non-warranty expenses and a brief summary of
the problem. Your original sales receipt must also be
included for warranty consideration. Be sure your name,
address, and RMA number are clearly written on the
outside of the shipping carton.

Warranty Inspection and Repairs

To receive warranty service, you must include your
original sales receipt verifying the proof-of-purchase
date. Provided warranty conditions have been met,
your Product will be repaired or replaced free of
charge. Repair or replacement decisions are at the sole
discretion of Horizon Hobby.

Non-Warranty Repairs

Should your repair not be covered by warranty the
repair will be completed and payment will be required
without notification or estimate of the expense unless
the expense exceeds 50% of the retail purchase cost.
By submitting the item for repair you are agreeing
to payment of the repair without notification. Repair
estimates are available upon request. You must
include this request with your repair. Non-warranty
repair estimates will be billed a minimum of ½ hour of
labor. In addition you will be billed for return freight.
Please advise us of your preferred method of payment.

Horizon accepts money orders and cashiers checks,
as well as Visa, MasterCard, American Express, and
Discover cards. If you choose to pay by credit card,
please include your credit card number and expiration
date. Any repair left unpaid or unclaimed after 90 days
will be considered abandoned and will be disposed of
accordingly. Please note: non-warranty repair is only
available on electronics and model engines.

United States:

Electronics and engines requiring inspection or repair
should be shipped to the following address:

Horizon Service Center

4105 Fieldstone Road

Champaign, Illinois 61822

All other Products requiring warranty inspection or
repair should be shipped to the following address:

Horizon Product Support

4105 Fieldstone Road

Champaign, Illinois 61822

Please call 877-504-0233 or e-mail us at
[e-mail] with any questions
or concerns regarding this product or warranty.

United Kingdom:

Electronics and engines requiring inspection or repair
should be shipped to the following address:

Horizon Hobby UK

Units 1-4 Ployters Rd

Staple Tye

Harlow, Essex

CM18 7NS

United Kingdom

Please call [phone] or e-mail us at
[e-mail] with any questions or
concerns regarding this product or warranty.

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LOSR2124

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LOSR2128

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LOSR2112

LOSR2113

LOSR2128

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LOSR2110
LOSR2111

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LOSR2111

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Losi 3.4
Rear Exhaust Engine

Engine Components

LOSR2110 3.4 Pist/Sleeve/Rod/Wrist Pin ...............................$89.99

LOSR2111 3.4 Connecting Rod w/Clips ..................................$29.99

LOSR2112 3.4 Crankshaft .........................................................$56.99

LOSR2113 3.4 Crankcase .........................................................$39.99

LOSR2114 3.4 Backplate & O-ring ..........................................$11.99

LOSR2115 3.4 Front Bearing ....................................................$14.99

LOSR2116 3.4 Rear Bearing .....................................................$18.99

LOSR2117 3.4 Combustion Chamber .......................................$8.99

LOSR2118 3.4 Head Gasket Set (.1 & .2mm) ...........................$3.49

LOSR2119 3.4 Heatsink – Orange ...........................................$44.99

LOSR2121 3.4 Head Protector & Screws...................................$4.99

LOSR2123 3.4 Carburetor Complete ........................................$44.99

LOSR2124 3.4 Carb O-Rings & Bellows ...................................$4.99

LOSR2126 3.4 Starter Rotor/Shaft .............................................. $6.99

LOSR2128 3.4 Screw/Hardware Set (10) ...................................$7.99

LOSR2129 3.4 Exhaust Seals (2) ...............................................$4.99

© 2008 Horizon Hobby, Inc.

Losi engines are manufactured in

Taiwan and distributed worldwide by:

Horizon Hobby, Inc.
4105 Fieldstone Rd.

Champaign, IL 61822

Customer support

1-877-504-0233

www.horizonhobby.com

www.losi.com

800-0377