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find the answer you are looking for, send us an email and we will be glad to help
with your questions!
·Is DDM an authorized dealer?
Yes, DDM is
a direct factory-authorized dealer or distributor for each of the following
manufacturers and brands:
HPI Racing R/C Products
FG Modellsport R/C Products
NGK Spark Plugs
DDM is also a direct factory-authorized dealer or distributor 0.for each of
the following smaller manufacturers:
ADA Racing - AMS - CAT5 - Craftwerks -
DarkSoul - Earth Surfer Products - Gabe Brown Engineering (GBE)
Golden Horizon - Jet-Pro - LunaTik - Outerwears - PhatDad-RC - Proline Racing
- RamTech - RC4WD - TeamFastEddy
TeamGoNads (TGN) - Trevor Simpson - Turtle Racing - Vertigo Performance
We work directly with the best in order to bring you a wide variety of
products at unbeatable pricing.
·Does DDM match prices?
Depending on the circumstances, possibly. We generally cannot match clearance
or other exceptional pricing. Call 801 619 0235 for a competitive price
quote over the phone. DDM believes that offering a fair price, great
service, and providing extensive on-line resources is best for our
·Can I get some free DDM stickers? Sure :) Send us a S.A.S.E.
(self-addressed, stamped envelope. This is an envelope with your return
address and a stamp on it. We will put the stickers in the envelope you send
and mail it back to you.) So, you need 2 envelopes with stamps:
1 large envelope addressed to:
DDM Sticker Request
228 West 12300 South, Suite 106
Draper, UT 84020
Inside this envelope, put another stamped envelope addressed to you. We will
put the stickers in this envelope and mail them back to you.
If you have a CY engine ( CY23RC "Fuelie", CY29RC, GP290,
etc) you can look at the Zenoah G230RC manual above for general tips.
You will need the Adobe Acrobat reader to view these files - you can
download it for free at http://www.adobe.com
My engine seems
sluggish and won't get up to speed? If
your engine has sluggish acceleration, is difficult to start and seems
to have low wide open throttle speed, you may have a plugged exhaust.
Check the muffler tubing for blockages. Remove the muffler and check the
exhaust port for carbon deposits. Also, if you are using a stock
muffler, check to see if the spark arrestor screen (internal muffler
packing) is clogged with carbon.
Fuel leaks out
of the carburetor into my air filter. How can I fix this? This
usually happens when dirt or other debris gets lodged in the carb needle
and seat area. The gas cap on many RC vehicles has a one-way valve. Air
can come in to replace used fuel, but nothing can get out. If the tank
becomes pressurized from a hot day or from heavy engine use, the
pressure will push fuel through the fuel lines and into the carb. Since
there is foreign matter causing the needle to stick, the fuel usually
runs out the front of the carb and into the air filter foam. Clean your
carb thoroughly with a can of spray carb cleaner. (See directions under
'how do I tune my carb' on this page).
A small amount of fuel in the air filter can also be caused by
"blowback" inherent in a piston-port two cycle engine design.
This is normal.
How can I tell
if my spark plug and ignition coil are working?
Over time, spark plugs wear out and need to be replaced. If you think
you may need a new plug or ignition coil, here is an easy test:
Remove the plug from the cylinder. Make sure the wire is still connected
on top, and place the tip of the plug close to the cylinder. Pull the
pull start a few times. If your plug and ignition coil are working, a
spark will jump from the plug to the cylinder. If you do not get a spark,
you may need to replace your plug or coil.
How can I tell
what type of engine my R/C vehicle has? Here
are pictures of engines commonly used on large scale RC products.
Chung Yang CY23RC / CY26RC / CY27RC / CY29RC
Zenoah G230RC / G260RC
Chung Yang GP290
Zenoah G231PUH / G260PUH
Zenoah G62 (large scale airplanes)
CY 26cc Marine Engine (boats)
Zenoah G231PUM / G260PUM Marine Engine (boats)
·There are lots of different engines available
for large scale RC. How fast are they, and how can I choose the right one for
On a fixed gearing R/C vehicle, there are two ways to go faster:
1) Make your engine rev (spin) faster. This is generally accomplished with
high performance parts and high performance engines.
2) Go further with each spin (change your gearing). This is generally
accomplished by using different drive gears. However, there is a limit to how
much you can increase your gearing. Eventually, the motor is not strong
enough to pull the additional load - it's like trying to start your manual
transmission car in 4th gear from a dead stop.
For example, lets compare the CY23RC engine and the CY29RC engine. The CY23RC
is rated at 2.5 horsepower. The CY29RC is rated at 3.5 horsepower. With
similar gearing, both engines will give you about an equal top speed. Why is
the speed similar, when one engine is much more powerful? Because the engines
spin at about the same maximum revolutions per minute (RPM). But
wait... the CY29RC puts out more power - which means that it can generally
handle higher gearing than the CY23RC can handle. You can install taller
gearing on your CY29RC and go much faster. Additionally, engines with higher
horsepower will generally accelerate more quickly.
A general rule of thumb can be: if you want to go fast, get an engine with
the most horsepower and 'gear it up'.
91 octane or
91 octane or higher
87 octane or higher
91 octane or
91 octane or higher
91 octane or
91 octane or higher
91 octane or higher
·Many engines require 91 octane (R+M/2 octane rating
method) or higher gasoline. Where can I find it? Using "Premium" pump gasoline is a good choice for
How should I
adjust the jets on a Walbro Carburetor (WA-167 / WT-603 / WT-668 /
WT-257 / WT-813, etc)? These
carburetors require regular adjustment to ensure peak performance, and
also to avoid an unsafe lean condition, which can prematurely damage
If you find your top-end RPM's have fallen
off a bit, or if you experience lagging or surging, it is probably time
to re-adjust the carb jets. To ensure max performance and engine life,
follow this procedure: 1) Locate the low and high RPM jets on the
side of the carb - they are usually marked with a L and a H. Turn both
jets completely CLOCKWISE ( to the fully closed position). 2) Rotate the Low jet counter-clockwise to 1 and 1/4 turns open. 3) Rotate the High jet counter-clockwise to approx 1 and 3/8
turns open. 4) Now, start the engine. You may need to turn the Low jet
slightly one way or the other for the engine to start. 5) Adjust the Low jet as desired until the idle is where you like
it. Turning clockwise ("CLOSING" THE JET) will
produce a higher idle, and counterclockwise ("OPENING" THE JET) will produce a
lower idle (and eventually flood and the engine will kill, if you turn
it too far). 6) Open the throttle lever to full blast. Adjust the High jet
until you get maximum RPMs. Note: this will probably be REALLY LOUD. Listen for the
highest-pitched whine to tell you where max RPMs are hit. AFTER YOU
FIND THE MAXRPM
SETTING, TURN THE HIGH JET
COUNTER-CLOCKWISE ("OPEN" THE JET)
APPROX 1/16TH OF A TURN TO ENSURE YOU HAVE SUFFICIENT GAS/OIL MIX
TO COOL THE
Note: The above are just general guidelines. You may need to adjust both
the H and L screws once you begin driving, depending on engine loading,
altitude, humidity, etc. The trick is to find settings that work well
for you, and stick with them.
is some helpful information regarding common carburetor tuning problems:
If your engine stutters at full throttle and cannot reach full
The high jet is too far open. Close the jet by turning it
clockwise slightly, and then ride-test. If no improvement, repeat until desired
results are achieved. Once you have found a workable setting, open the
jet approx 1/16 of a turn to ensure sufficient fuel/air mix.
If your engine bogs out when transitioning from low speed:
The high jet is too far closed. Open the jet by turning it
counterclockwise until you are at least 1 1/2 turns open, and then
gradually close the jet until performance is as desired. Poor engine
compression, blocked exhausts, and very heavy engine loading can all
also cause bogging.
If your engine idles very fast and kills if you attempt to slow the
You may have an air leak in your intake. An easy way to check for leaks
is to spray the intake manifold and area surrounding it with WD-40. If
the idle changes after you spray the WD-40, there is an air leak. Common
areas for leaks are between the manifold and the cylinder, and between
the carb and the intake manifold. Inspect the manifold, carb gasket, and
intake gasket for cracks or other signs of damage, and replace if
If your engine idles but then slowly kills:
Your low jet is too far open. Close the low jet by turning it clockwise
until a stable idle is achieved.
What are the
recommended carburetor needle settings for my engine? DDM
recommends the following tuning as a STARTING POINT for tuning your
G230RC / G260RC / CY23RC / CY26RC / CY27RC / CY29RC / GP290 engines: 1
and 1/4 L, 1 and 3/8 H.
What Spark plugs
will work in my Zenoah or Chung Yang RC-style engine? What electrode gap
is correct? For
the Zenoah RC-style engines and clones, the following plugs work well:
This plug works the BEST: NGK CR8HIX Iridium Plug
A gap of .65mm (.029 inches) is recommended.
How should I install
a new big-bore kit on my Zenoah or Chung Yang RC-style engine? Here
are some basic instructions to help you install a new big-bore kit or
replacement top end for your motor:
1) Remove all outer engine parts from your current engine - remove the
airfilter, carburetor and intake manifold; remove the engine shroud and
ignition coil, disconnect the muffler, etc. The cylinder should now be
bare with nothing attached to it.
2) Remove the cylinder by removing the bolts holding it to the
crankcase. Gently slide the cylinder up and off. Remove the old cylinder
3) Separate the piston from the crankshaft. Remove the c-clips which
hold the piston on the piston pin and bearing. Slide the piston off, and
remove the piston pin, washers, and pin bearing if your kit includes new
4) Put the piston ring on your new piston. Slide it down over the top.
Be careful not to bend the ring or it may break. Make sure the gap in
the piston ring is aligned with the little nub in the piston ring groove
on the piston.
5) Re-connect the piston to the crankshaft. Make sure the arrow or dot
on the piston is toward the exhaust (not intake) side of the engine.
Make sure you have the pin washers at both sides of the piston pin.
Install the c-clips at both sides to ensure the piston is securely
attached. Make sure these clips snap securely into their grooves.
6) Place the new cylinder gasket on the crankcase. Slide your new
cylinder down over the piston and ring. You may need to compress the
piston ring slightly to get the cylinder on. Again, make sure the gap in
the ring is aligned with the little nub in the piston ring groove. Slide
the cylinder down slowly and smoothly. Try not to wiggle or twist it too
much to avoid scoring the cylinder.
7) Reconnect the cylinder to the crankcase. Tighten the bolts firmly.
8) Reinstall the carb, filter, muffler, shroud, coil, etc removed in
step 1. When reinstalling the ignition coil, place a business card
between the coil and the flywheel. Turn the flywheel so that the magnets
pull the coil and flywheel together, pinching the card. Now, tighten the
ignition coil bolts. This will ensure you have a proper gap between the
coil and flywheel.
9) Once all parts are reinstalled, fire up your new engine and enjoy
your new, more powerful machine! Be sure to heat-cycle the engine
several times (run the engine for a few minutes at a low, varied
throttle, turn it off and allow to cool, then repeat) in order to allow
the new parts to properly seat themselves.
How should I
Zenoah or Chung Yang RC-style engine? Zenoah
RC-style engines and clones are tuned for high performance and need
to be well taken care of. Breaking-in an engine is a process of
alternately heating and cooling the engine to allow all parts to properly
seat themselves, and allowing 2-stroke oil from the incoming fuel to
coat the interior of the engine. DDM recommends the following break-in
Use 91 octane or higher fuel, mixed 25:1 with a quality non-synthetic
2-stroke oil. (You can use synthetic oil for break-in also. Just
run slightly more fuel through the engine. ) Run the engine at varying
speeds for periods of 3 to 10 minutes at a time. During this break-in
time, NEVER go full throttle. Always let the engine idle for 30 seconds
before turning it off. Allow the engine to cool off for 10 minutes
before starting it again. Repeat this process 3 or 4 times - 3 or 4 full
After the break-in period, switch to a high-quality synthetic 2-stroke
oil, mixed at 25:1. Be sure to let the engine idle for 30 seconds to
cool before stopping. Be sure to follow the maintenance schedule
included in your engine owners manual.
Help! My Zenoah
or Chung Yang RC-style engine won't start! What's wrong? This
engine is tuned for high performance and needs to be well taken care of.
If your engine won't start, check the following things: 1) Are you using high octane gasoline? 91 octane or higher is
needed. Using octane booster is not recommended. 2) Are you using high-quality 2-stroke oil mixed at 25:1? This
is 5 ounces of oil per gallon. DO NOT USE any oil labeled as
'TCW-3', 'MARINE' or 'OUTBOARD' oil. These are designed for
low-revving, water-cooled oil-injected motors (such as personal
watercraft), and your engine will likely not run well if you use them. 3) Are you using the choke properly? On the side of the
carburetor there is often a choke lever. Horizontal is open, vertical is
closed. Lever should be closed when first starting. As soon as the
engine sputters at all, move the choke to open and leave it there.
4) Is your spark plug clean and working? Remove the plug from the
engine and inspect the tip. Is it clogged with gunk or debris? Clean if
necessary. After the plug is removed, check if the plug is working by:
attaching the wire to the top of the plug, and place the tip of the plug
very close to the metal of the cylinder. Pull the pull start a few
times. A spark should jump from the plug to the cylinder. If no spark or
weak spark, replace the plug, ensure the ignition coil and flywheel are
properly gapped, then check again. If still no spark - you likely have a
problem with the ignition coil, and will need professional service. 5) Is your carburetor properly tuned? Rotate the 'H' and 'L'
screws on the side of the carb fully clockwise ('closed'). Then, turn
the L screw counterclockwise ('open') 1 and 1/4 turns. Turn the H screw
open 1 and 3/8 turns. You may need to adjust these screws slightly in
either direction to find correct tuning for your carb. 6) Is your engine flooded? If you have pushed the primer bulb a
lot of times, or pulled the pull start a lot of times, the engine may be
flooded. Remove the spark plug, and allow all the fuel in the cylinder
to evaporate. You can speed up this process by blowing on it with a hair
dryer, and/or by turning the engine upside down with the spark plug out
and pulling the starter a few times to purge accumulated fuel from the
crankcase. 7) Are you getting good compression? If you have used your engine
for an extended period of time, the piston ring may need replacement.
See instructions below. 8) Do you have a gasket leak? Check your carb gasket, intake
gasket, cylinder gasket, and crankcase gasket. Can you hear air
whooshing out of the cylinder gasket or crankcase gasket when you pull
the starter? Is air leaking in the manifold gasket behind the carb? A
gasket leak results in a loss of compression and/or improperly mixed
fuel and air. An easy way to check for intake leaks is to spray the
intake manifold and area surrounding it with WD-40. If the idle changes
after you spray the WD-40, there is an intake air leak. Common areas for
leaks are between the manifold and the cylinder, and between the carb
and the intake manifold. Inspect the manifold, carb gasket, and intake
gasket for cracks or other signs of damage, and replace if necessary.
If your engine still won't start, you will likely need professional
service on your engine.
How do I change
the Zenoah or Chung Yang RC-style piston ring? If
your engine is losing compression, the ring may need replacing. Here's
Remove your air filter, carburetor and muffler. Remove the fan cover and
the engine cover. Remove the ignition coil, and then remove the two
cylinder bolts. Keep them safe. Remove the cylinder by pulling firmly
upwards. Do not rotate, twist, or bend the cylinder, or slide it up and
down. Remove the old ring by carefully breaking it off, or bending it
and pulling it off the top of the piston. Try to avoid touching the
piston or inside cylinder with your bare hands - your body oils or other
foreign matter on your hands may harm the engine... you may want to
consider wearing clean latex gloves. Now, carefully install the new ring
by bending it over the top of the piston. You can put the ring in the
oven at 200° for a few minutes to warm it up and make it less likely to
crack during installation. Place a drop or two of 2-stroke oil on the
edge of the ring. You can also put in a new base gasket now if your
current gasket needs replacing. Slide the cylinder back on smoothly (no
twisting or up and down) and replace the cylinder bolts. Re-install the
ignition coil, engine cover and fan cover, muffler, carb, and filter.
Follow the break-in instructions above to allow the new ring to seat
How does a tuned
pipe exhaust work? Why will it increase the performance of my engine? A
"tuned pipe" is the common name for a Helmholtz resonator. An
example you are probably more familiar with is an organ pipe, which
resonates or is "tuned" to a particular frequency. 2-stroke
engines also make a sound wave with a particular frequency. As the RPM's of your
engine get higher, the pulses of exhaust gas coming out of your engine
bounce back and forth inside the pipe and create a "standing
wave". Areas of high and low pressure are created. The exhaust is
sucked quickly out of the low pressure areas. Tuned pipes create a low
pressure area directly behind the cylinder, and exhaust is sucked
quickly out of the cylinder! This makes more room for fresh air and
fuel, and thus: more power for your vehicle. Additionally, return waves
help push back incoming fuel/air mix, keeping it in the cylinder to be
burned. This is why tuned pipes are an excellent investment, despite the
cost. Other systems, such as aftermarket mufflers with two exhaust
tubes, simply reduce the back pressure from the muffler. They cannot
create a standing wave which leads to low pressure at the exhaust port.
How can I tell
how fast my R/C vehicle is? One
approach is to mount an onboard GPS unit.
to measure your vehicle speed is: use a speed trap. All official speed
records are measured this way. Here's how a simple speed trap works:
We want to find out how many feet per second the vehicle is traveling.
This is easy to do.
Measure off a known distance on a street (at least 200 feet). 300
or more feet is better and will be more accurate. Mark a start line and
a finish line.
Now, get a long running start from further down the street, so your
vehicle is going FULL SPEED on your
vehicle when you cross the start line.
With a stopwatch, have someone time how long it takes the vehicle to
travel from the start line to the finish. This is best accomplished as
Have the person with the stopwatch stand at the start line, and start
the timer when the vehicle crosses the line. Have another person with a
flag or something stand at the finish line. When the vehicle crosses the
finish line, quickly lower the flag. The person with the stopwatch
should stop the timer when the flag is lowered.
Let's say it took your vehicle 3.4 seconds.
This means that it was going (200 feet / 3.4 seconds) = 58.8 feet per
But how many MPH is that?
There are 60 seconds in a minute and 60 minutes in an hour, so there are
(60 * 60) = 3600 seconds in an hour.
This means it was going (58.8 feet/sec * 3600 sec/hour) = 211,764 feet
There are 5,280 feet in a mile, so your vehicle was going (211,764 /
5280) = 40.1 MPH. Not bad!
The general formula for finding MPH from Feet Per
Second is: FPS * .682 = MPH.