Duratrax Velocity 17 User manual

Thank you for purchasing a DuraTrax engine – designed to provide
easy starts and all the power you'll need for thrilling R/C action.
The following instructions contain information you'll need to break-in,
operate and maintain your new engine like a pro. Read and follow
them carefully, and your engine will provide a long life of strong,
dependable performance.
• Model engine fuel is poisonous and must be kept in a clearly marked
container, stored away from the reach of children.Avoid getting fuel into
your eyes or mouth.
• Because model engine fuel is highly flammable, it should also be kept
away from anything that might cause it to ignite (including open flames,
excessive heat, or any objects and materials which could produce a
spark). Smoking must not be permitted near the fuel.
• R/C model engine exhaust, like that of automobile engines, contains
deadly carbon monoxide. Do not run the engine in enclosed spaces –
operate it only in open, well-ventilated areas.
• Your engine will become very hot as it runs. Touching any part – particu-
larly the muffler (silencer), cylinder head or exhaust header pipe – could
result in a serious burn. Avoid contact with the engine until it has cooled.
• Protect onlookers – especially small children – by making sure that
they remain at least 60 feet (20 meters) away while you start the engine.
• This engine was designed only to power R/C model vehicles and
should not be used for any other purpose.
• Never pull the starter cord out more than 10 inches (25cm).To rewind
the cord, continue holding the handle and let the recoil action pull it
smoothly back into the starter unit. Do not abruptly release the handle.
The High-Speed Needle
The “high-speed” needle is sticking up from the side of the carb. It is
located in the brass housing, just above the fuel inlet. It controls the
fuel-to-air mixture of the carb. The needle is pre-set for break-in from
CARBURETOR SETTINGS
ADDITIONAL PRECAUTIONS
FORYOUR SAFETY
INTRODUCTION
®
ENGINE INSTR
ENGINE INSTRUCTIONS UCTIONS
Warranty
•DuraTrax®will warranty this engine for 90 days after the pur-
chase date from defects in materials or workmanship. DuraTrax
will either repair or replace, at no charge, the incorrectly made
part.
•Make sure you save the receipt or invoice you were given
when you bought your engine! It is your proof of purchase and
we must see it before we can honor the warranty.
•To return your Velocity 17 for repairs covered under warranty
you should send your engine to:
Hobby Services
1610 Interstate Drive
Champaign, Illinois 61822
Attn: Service Department
Phone: [phone]:00 am - 5:00 pm Central Time M-F
E-mail:
[e-mail]
Repair service is available anytime.
•After the 90 day warranty, you can still have your Velocity 17
repaired for a small charge by the experts at DuraTrax’s
authorized repair facility, Hobby Services, listed above.
To speed up the repair process, please follow these instructions:
Send written instructions which include:a list of all items returned,
a THOROUGH explanation of the problem, the service needed
and your phone number during the day. If you expect the repair to
be covered under warranty, be sure to include a proof of date of
purchase (your store receipt or purchase invoice).Also be sure to
include your full return address.
TM

the factory at 2-3/4 turns out from the fully closed position of the carb.
Once the engine is broken-in, the high-speed needle would typically
run from 2-1/4 to 2-1/2 turns out from closed, depending on the weath-
er, humidity and altitude above sea level. To richen turn the needle
counterclockwise, to lean turn the needle clockwise.
The Low-Speed Needle
The “low-speed”needle is the screw in the carb body, opposite the throt-
tle arm (see picture on previous page).It controls the fuel to air mixture at
low throttle settings.There is a simple way of adjusting the low-speed nee-
dle correctly called the “pinch test.”With the engine at idle, pinch the fuel
line and listen to how the engine speeds up or slows down. If the engine
increases its speed for about 2 or 3 seconds and then loses RPM, the
needle is set correctly. If the engine loses RPM quickly, it is set too lean
and the low-speed needle needs to be opened (counterclockwise) to
richen the mixture. Pinch again
to check the mixture. If the engine takes
longer than 4
seconds to slow down, lean (clockwise) the low-speed nee-
dle and then pinch again to check the mixture. Use small adjustments
when setting the low speed needle. Start with 1/16 turn increments.
The Throttle Stop Screw
On the front of the carburetor, there is a black screw (see picture on previ-
ous page).This is called the throttle stop screw.This increases or decreas-
es the idle RPM without changing the fuel-to air-mixture.You should see an
opening of approximately 1.5mm (between 1/32" and 1/16") between the
carb body and the carb barrel when the throttle is pushed closed.
Before running, please, read this manual thoroughly to familiarize your-
self with this engine.
There are several simple steps to starting the engine:
1. Install a glow plug if one is not in your engine.This threads into the
top of the cylinder head.
2. Fill the tank almost to the top. Leave a little air at the top of the tank.
3. Prime the engine by turning the flywheel on the engine. Watch the
fuel go through the line and when it gets to the carburetor, turn the
flywheel one more full revolution.
4. Open the high speed needle valve exactly 2-3/4 turns out (coun-
terclockwise) from fully closed. Be careful not to overtighten the
high speed needle. When you feel some resistance, stop turning
the needle. The high-speed needle is sticking up from the car-
buretor inside the brass housing. All of the carburetor settings
are adjusted with a flat bladed screwdriver. If you have previously
run the vehicle, keep the same needle valve setting that you used
on your last run.
5. Install your glow plug starter onto the glow plug.
6. Start the engine by pulling the recoil - Use short, quick pulls. DO
NOT pull the recoil starter’s string to the end.You only need 10 inch-
es of pull to start the engine.
If the engine does not start after several pulls, sometimes it is helpful to
start the engine at around half throttle. Have a friend pull back on the
throttle some while you start the engine. This
may be an indicator that
the low speed needle setting needs to be adjusted. When the engine
starts, immediately return the throttle to idle. If this is not done the
engine can over-rev and cause engine damage. If the engine is diffi-
cult to turn over with the recoil starter,especially if it is brand new,
loosen the glow plug a half turn before starting the engine. This
allows some compression to escape, but the engine will still start.
Make sure you tighten the glow plug after the engine starts. If the
recoil starter is still difficult to pull, the engine is flooded –there is too
much fuel inside the engine. Remove the glow plug and air cleaner,
then turn the engine upside down and pull the recoil 5 or 6 times.This
will clear the engine of fuel, and you will notice the recoil pulls easier.
Replace the glow plug and repeat the starting procedure.
Fuels
Use fuels that are specially formulated for car and truck engines.
DuraTrax Red Alert fuel is specially formulated for R/C engines like the
Velocity .17.
How To Stop Your Engine
You may have been wondering how to stop the engine. All you have to
do is pinch the fuel line that runs to the carburetor and from the bottom
of the fuel tank. Pinching this will restrict the fuel flow and the engine
will quit within a few seconds.You can also touch the flywheel with the
tip of your shoe through the hole in the bottom of the chassis.
To insure long life and good performance from your Velocity .17 engine,
you MUST break-in the engine. The break-in period is critical for long
life of the internal parts of the engine.This should be done over the first
5 or 6 tanks of fuel.
Some ThingsTo Remember During Break-In:
1. Run with the body off. This will keep the engine cooler.
2. Keep the air cleaner on at ALL times.
3. Run on a smooth, hard surface. An empty parking lot is perfect.
4. Use the same fuel that you will use for normal running.
5. Resist the urge to accelerate and decelerate the vehicle quickly.
6. Break-in puts stress on the glow plug and you can burn it out dur-
ing break-in. Make sure you have an extra plug or two on hand.
7. Do NOT overheat the engine.You can check the head temperature
by using one of the temperature gauges that are available.
The First Tank
Your first tank of fuel should be running the engine at a very rich high-
speed needle valve setting. This allows the fuel to carry as much oil as
possible into the engine to lubricate the internal parts during the break-in.
1. Open the needle valve 2-3/4 turns from fully closed (counterclockwise).
This is factory set already, but check it to make sure.When closing the
high-speed needle, close the needle until you feel some resistance.DO
NOT overtighten or you will damage the engine.
2. Start the engine.
3. Once the engine is started, open the high-speed needle valve
around 1/8 turn at a time, finding the setting where the engine just
barely runs. This may take a few times adjusting the needle, run-
ning the vehicle away from you and back, then adjusting the nee-
dle.The engine will perform sluggishly and stall from time to time -
that is normal.
4. Run the vehicle back and forth at medium speeds, slowly acceler-
ating and decelerating the vehicle, until the tank is almost out of
fuel. Do not allow the tank to run out of fuel. This leans out the
engine and can cause overheating.
5. Stop the engine and allow the engine to cool before the second
tank. This normally takes around 10 minutes (See How To Stop
Your Engine).
Tanks 2-6
Turn in the needle valve (clockwise) around 1/12 turn from the previous
setting. Run the vehicle back and forth. You should notice that the
engine will perform better during each run. Stop the vehicle periodical-
ly to check for overheating. If it is too hot, stop the engine.Wait for it to
cool, then open up the needle valve 1/4 turn and restart. After the 6th
tank, you should be near to the peak performance of the engine.
BREAKING-IN THE ENGINE
RUNNING THE ENGINE
1/32"TO 1/16" GAP
THROTTLE STOP SCREW

40
39 38 42
43
44
48 47
46
45
14 15 7
51
1
2
5
11 4
12
10
11
9
6
33
34 35
36
8
3
19
18
16 13
32
32
17
20 21 22
23
24
25
27
28
30
29
31
26
41
50
37
49
Ten WaysTo Ensure A Long Life FromYour Engine:
1. Keep your engine clean. Dirt will act as insulation on an engine. It
will not be able to shed heat as easily. Use a good air filter to keep
dirt out of your engine and clean it often.
2. Do not over-lean your engine.
3. Do not run your engine with little or no load.Don’t throttle up the engine
to full throttle when the wheels are not in contact with the ground.
4. Do not overheat the engine.This goes along with keeping it clean
and not over-leaning the engine.
5. Do not use a fuel with a low oil content. Make sure you use a fuel
from a reputable manufacturer, such as DuraTrax Red Alert.
6. Avoid using old fuels in the engine.Always run all of the fuel out of the
engine. After running for the day, use an after-run oil and work it into
the engine by turning the flywheel or pulling the engine recoil slowly.
7. Do not use a fuel with a nitromethane (often called nitro) content
over 20%.
8. Do not scratch the piston or cylinder sleeve. Avoid jamming some-
thing into the exhaust port when removing or re-installing the
clutch or flywheel. Use a special tool called a crankshaft locking
tool (not included), which is installed in the glow plug hole.
9. Do not use silicone sealer on the engine joints.Silicone sealer con-
tains acetic acid, which is corrosive if it gets inside your engine.
10. Do not allow any water inside the engine. This sounds
easy, but
temperature changes can cause
condensation inside the engine.
This is a good reason to use an after- run oil. Store your engine
inside the house, not in a garage or shed where there will be tem-
perature extremes.
If you are having problems with your engine consult the engine
troubleshooting on the back page. The following are some poten-
tial problems.
Glow Plug
The glow plug is an item that will wear out and need replacement from time
to time.It is a good idea to remove the glow plug before your first run, heat
it and see how well it glows.You should see a bright orange glow from the
filament. If a coil or two will not glow or the plug will not glow at all, replace
the plug. If the engine quits when you remove the glow starter, the plug
might need to be changed, although this may be because you are running
too rich and need to screw in your high-speed needle some. Look at the
glow plug when you are running the engine.If you see some bubbles com-
ing from around the plug, replace the glow plug (copper) gasket, or both the
plug and gasket.The only real way to test a glow plug is to replace it. Make
sure you have a spare plug or two on hand when you run the engine.
Fuel
Fuel can go bad. The main ingredient in model fuel is methanol, which
is basically an alcohol.Alcohols can absorb water out of the air, so keep
your fuel jug capped at all times. Store your fuel out of the sunlight and
in a cool place.Bad fuel is one of the most difficult problems to diagnose
in engines. If you have tried everything you can think of to remedy an
engine that is not running correctly, try using some fresh fuel.
Fuel line is susceptible to pinhole leaks.You cannot see the hole in the
fuel line, but if you see air bubbles in the line going to the carburetor,
replace the fuel line. Another symptom of a leak in the fuel line is a
surging engine.The properly tuned engine will surge when the air bub-
bles hit the carb. It is basically leaning out the mixture.
To keep dirt out of the engine, use an inline fuel filter on the fuel line
running from the fuel tank to the carburetor. Dirt can get caught in the
needle seat and cause an inconsistent running engine. If you suspect
that some dirt has lodged itself in the carb, remove the needles and
clean the carb with denatured alcohol or fuel. It can help to use com-
pressed air to blow out the fuel passages as well. Dirt can get into your
carburetor and engine through the air filter. Ensure that your air clean-
er has a good seal to the top of the carb. Periodically wash the air
cleaner foam element and re-oil the filter.Any air cleaner that has a torn
element or a bad seal should be replaced immediately.
Overheating
One of the worst things you can do to your engine is overheat it.The oils
that lubricate the engine are carried in the fuel. If your engine is set too
lean, there will not be enough oil in the engine to lubricate the internal
parts.This will cause premature wear in the engine and cause damage.
We have talked about overheating in other parts of this manual, but we
want to stress the proper techniques to check for overheating.The easi-
est way of checking the temperature of the cylinder head is using one of
the available temperature gauges. This will give you a direct reading of
the cylinder head temperature. Do not let the head temperature exceed
240°Fahrenheit (115°Celsius). Another way of checking the head tem-
perature is to put a drop of water on the cylinder head.If it boils away with-
in 10 seconds, the high-speed needle is set too lean. If the water boils
away in around 15 seconds, the engine is within proper operating tem-
peratures. If the water boils away longer than 15 seconds, the mixture is
set rich which is preferable when breaking in the engine. Otherwise lean
the mixture some and retest after a minute of running.
ENGINE MAINTENANCE
Stock # Description ...........................Includes
DTXG0352 Bearing Front.............................7x1pc
DTXG0362 Bearing Rear..............................8x1pc
DTXG0380 Carburetor Barrel.....................38 x1pc
DTXG0401 Carburetor Boot / Dust Cover..39 x1pc
DTXG0411 Carburetor Body.......................37 x1pc
DTXG0415 Carburetor Barrel Spring..........42 x1pc
DTXG0460 Carb Retainer & Nut ......34,35,36 x1pc
DTXG0468 Carburetor O-Ring ................51 x2pcs
DTXG0472 Connecting Rod.........................2x1pc
DTXG0496 Coverplate for Recoil...............17 x1pc
Stock # Description
DTXG0502 Coverplate Gasket...................13 x1pc
DTXG0511 Coverplate Screws.................32 x4pcs
DTXG0523 Crankcase..................................1x1pc
DTXG0535 Crankshaft..................................3x1pc
DTXG0554 Cylinder Piston Set.................4,5 x1pc
DTXG0557 Fuel Inlet Nozzle......................48 x1pc
DTXG0562 Drive Washer ...........................14 x1pc
DTXG0566 Drive Washer Collet.................15 x1pc
DTXG0573 Head Button...............................9x1pc
DTXG0586 Heatsink Head Black .................6x1pc
DTXG0592 Heatsink Head Gasket.............12 x1pc
DTXG0602 Head Screws..........................33 x4pcs
DTXG0604 Idle Needle...............................49 x1pc
DTXG0607 Idle Needle O-Ring ................50 x2pcs
DTXG0617 Needle Socket..........................47 x1pc
DTXG0622 Needle Valve............................45 x1pc
DTXG0630 Needle O-Ring.........................46 x1pc
DTXG0635 One-Way Bearing ...............20,21 x1pc
DTXG0642 Piston Pin.........................................10 x1pc
DTXG0655 Piston Pin Retainers ..............11 x2pcs
DTXG0752 Recoil Starter......22,23,24,25,26,27,28
......................29,30,31 x1pc, 32 x3pcs
DTXG0762 Start Shaft................................16 x1pc
DTXG0776 Start Shaft Pin .........................19 x1pc
DTXG0782 Start Shaft Spring....................18 x1pc
DTXG0802 Throttle Arm........................40,41 x1pc
DTXG0811 Throttle Stop Screw............43,44 x1pc
Optional:
DTXG0442 Carburetor Slide Valve........Not Shown
DTXG0497 Coverplate Standard...........Not Shown
DTXG0587 Heatsink Head Purple.........Not Shown
Exploded View and Parts List

ENGINE TROUBLE SHOOTING
The engine starts
Does the engine
turn over easily?
Does it run con-
tinuously?
Is fuel getting to
the engine?
Check for clogging in
the carburetor or fuel
line. Press the
primer pump and
check for fuel spray-
ing out of the fuel
line. If so, replace
the fuel line.
Is fuel in the
fuel line?
Is the glow plug
red hot?
Check the high speed needle
setting and prime the engine.
Is foreign matter
clogging the fuel
tank or fuel line?
Is the battery for
the glow plug
clip charged?
It should be
ready to go.
Is the high
speed needle
setting 2 to
2-1/2 turns out
from closed (if
the engine is
broken-in?)
Try starting the
engine again.
NO
NO
NO
NO
YES
YES
YES
YES
YES
Does the engine
quit when the
glow plug clip is
removed?
YES
YES
Clear the engine
of fuel.
NO
Reset the high
speed needle.
YES
NO
Replace the
glow plug.
Check that the
pressure line is
connected to the
muffler.The fuel
may be bad.
The engine does not start
NO
Does the engine
turn over easily
with the glow
plug removed?
The engine may
be flooded.
Clear the engine
of fuel.
YES
Check that
nothing is
caught in the
engine. Check
that the the
pull starter
operates
smoothly.
NO
Press the
primer pump
and check for
fuel spraying
out of the fuel
line through a
small hole. If
so, replace
the fuel line. YES
Remove the
obstruction from
the fuel tank or
fuel line.
NO NO Charge or
replace the
batteries.
YES
Replace the
glow plug.
Try starting the
engine again.
Entire Contents Copyright © 2002 DTXZ2604 for DTXG0220 v 1.0