Evolution Engines
26GT2/35GT2
USER G UI D E
®
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Introduction
Congratulations on your purchase of the newest and one of the most technically advanced 2-stroke gas model airplane engines in the
world. Whether you are new to the sport of model aviation or an experienced flyer, you will enjoy the features of the new Evolution GT engine.
Evolution engines are designed to be the most powerful in their class, extremely easy to start and operate, and provide years of enjoyable
service. These engines incorporate many unique design features. Each feature is designed to
ensure success with your new engine.
This user’s guide is intended to provide the basic information required to operate and maintain your Evolution GT engine.
Important: While the Evolution engine is extremely easy to operate, if this is your first experience flying a model airplane, it is highly
recommended that you have the help of an experienced modeler during the first few flights.
Your local hobby shop or flying club can put you in touch with an experienced pilot in your area.
Before using this engine, please read these instructions carefully.
Evolution Engines® 2-Year Warranty
This Evolution Engines product is
guaranteed to be free from defects in
materials and workmanship for a period of
2 years from the date of purchase. During
this time, Evolution’s authorized service
center will repair or replace, at their option,
any defective parts without charge.
This warranty does not apply to damage
or defects resulting from misuse, neglect
or abuse; damage caused by customer
disassembly, use of substandard fuel,
use of incorrect accessories (spark plug,
propeller, etc.); or damage resulting from a
crash or any use of this engine other than
for which it is specifically intended. Any
of the above will automatically void the
warranty of the engine.
Should your engine require warranty or nonwarranty repair service, please package
it carefully and return it to the address at
the right, along with a copy of the original
invoice or receipt and a detailed letter
explaining the problems. Write your name,
address and daytime phone number clearly
on the letter and return it via FedEx, UPS
or insured Parcel Post (Evolution Engines
will not be responsible for product lost en
route).
For repairs not covered under warranty,
please specify in your letter whether you
want an estimate of the repair charges prior
to performing the service (which may cause
a slight delay). Payment for non-warranty
repairs should be made by credit card or
money order. Unless otherwise specified, all
repaired engines will be returned. We will
do everything we can to expedite the service
required to your Evolution product.
_________________________________
Evolution/Horizon Service Center
4105 Fieldstone Road, Champaign, IL 61822
1-217-355-9511
www.horizonhobby.com
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Mounting the Engine
Most model airplane designs make provision for an engine
mount. It is extremely important that the engine mount be
securely mounted to the airplane’s firewall and that the engine
is securely mounted to the engine mount. Follow the instructions
included with the airplane for mounting the engine.
The engine should be fastened in place with 4 screws through
a conventional beam mount. Use 8x32 screws (26GT2) or 10x32
(35GT2). If you decided to fasten the engine using a flexible
motor mount, always choose parts with enough integrity and
strength. Make sure all screws are tightened and regularly check
that they are tight and in good condition.
Important: Air is necessary to cool the engine during operation.
Make sure that sufficient air circulation through the cowling is
provided. As a basic reference the outlet area should be 3–5
times the area of the inlet area to provide adequate cooling.
Throttle Linkage
Carefully attach the throttle linkage to the engine using a ball
link on the carburetor. Make sure that the linkage is free to
operate from low throttle to high throttle and confirm that the low
throttle setting on the transmitter closes the carburetor butterfly
to the low idle position. Adjust the length of the pushrod until full
throttle opens the carburetor butterfly fully, while low throttle, low
trim completely closes the butterfly.
Attaching the Fuel Lines
Use medium gasoline-compatible fuel line in the fuel tank
as well as the supply line to the engine.
Selecting a Suitable Propeller
The Evolution 26GT and 35GT have been designed to generate
maximum power at 8500 rpm, according to the type of exhaust
used. If you wish to utilize the maximum power output, choose a
propeller, which will allow the engine to reach these revolutions,
or slightly lower revolutions. (The engine will unload in the air
depending on the aircraft speed and propeller selected.) We do
not recommend using propellers that allow the engine to reach
more than 9000 rpm on the ground.
Fuel for the Evolution Gas Engine
The Evolution gas engine has been designed to run on a mixture
of high quality unleaded gasoline and synthetic oil intended
for racing 2-stroke gasoline engines. For the break-in period of
the new engine, mix the fuel in a ratio of 30 parts gasoline to 1
part lubricant. After break-in use a ratio of 40 parts gasoline to
1 part lubricant.
Suggested Propeller Dimensions
16x8 16x10 16x11 16x12
17x8 17x10 17x12
18x6 18x8
26GT2
18x8 18x10
19x8 19x10
20x8 20x10 20x12
35GT2
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1) Before attempting to start your engine make sure that the ignition is switched off, the choke valve is closed and the throttle
valve is about half opened. Then turn the engine 3–4 revolutions, assuming the engine has not been flooded.
2) When you are ready to start the engine switch the ignition on, open the choke valve and set the throttle at a slightly high idle speed.
Be sure to have a helper hold the model securely. Using an electric starter begin cranking the engine. It should fire within seconds of
applying the starter. Allow the engine to idle for 30–45 seconds.
3) If the engine does not start even after using the starter to crank the engine a second time, open the throttle to maximum, turn
off the ignition and turn the engine about 4 revolutions. Switch the ignition on again, then restart the engine with throttle at a
fast idle position and the choke valve set open.
4) At this point if the engine still will not start, unscrew the spark plug and check its contacts. Clean any possible excess fuel (i.e.
an indication of engine flooding) and screw it in again. Further starting should only be done with the throttle at idle position. If the
plug is dry then probably not enough fuel has been drawn into the carburetor. If that is the case, check the fuel feed and then return
to the instructions given in paragraph 1.
Starting the Engine
Evolution Engines® new carburetor comes adjusted to
a basic setting. This setting should be maintained
during the initial break-in runs.
Before you first start the engine, make sure that the spark
plug is screwed in and tightened and that the plug socket
is fitted in place and fastened down properly. Fix the ignition
sensor in the proper position above the magnet with the
screws enclosed. *Follow the directions in the ignition system
addendum to mount the ignition module in your model.
Important: Never turn the engine over with the ignition turned
on unless the spark plug is inserted in the plug socket. This
could lead to ignition damage.
Carburetor Adjustments 26GT2
Adjust needle (L) for low rpm range 1 turn and 50 minutes
Adjust needle (H) for high rpm 1 turn and 35 minutes
Basic setting: (minutes refer to the hands of a clock)
Carburetor Adjustments 35GT2
Adjust needle (L) for low rpm range 1 turn and 45 minutes
Adjust needle (H) for high rpm 1 turn and 45 minutes
Idle stop screw
Adjusting Needle L
( directly below Needle H )
Adjusting Needle H
Choke Lever
Pressure Inlet
Fuel Intake
Throttle Lever
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