RC Cars / Trucks / Buggies
FREQUENTLY ASKED QUESTIONS

If you don't 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
Zenoah Engines
Walbro Carburetors
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.

· What if I need to return a product?
No problem. You can view a copy of our terms of sale here.
All returns need to be accompanied by a completed product return form. You can download this form here.
The return form requires Adobe Acrobat to view - download it for free here.

· 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 customers.

· Does DDM ship internationally?
Yes, we do. Every day. More info is here:  http://www.davesmotors.com/goped-international.htm

· 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.

MAINTENANCE

• Can I get an owners manual for my engine?
  
  Zenoah owners manuals are here:
  Engine owners manuals: G230RC / G260RC G231PUM / G260PUM / G231PUH / G260PUH / G260PU G62PU
  
  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.
  
• Where can I find information on my carburetor?
  Here is some information on some common carburetors for small engines for use in R/C:
  (visit http://wem.walbro.com/walbro/family2.asp for more info)
  

Type	Carburetor Type	Exploded View
G230RC / G260RC Stock Carb	WT-603	View of WT-603
Chung Yang stock carb (CY23RC, CY26RC, CY27RC, CY29RC, GP290)	WT-668	View of WT-668
Alcohol carburetor for use on G23LH / G230RC / G260RC / CY23RC / CY26RC / CY27RC / CY29RC / GP290	WT-499
Zenoah recommended upgrade carb for G23LH / G230RC / G260RC / CY23RC / CY26RC / CY27RC / CY29RC / GP290	WT-813

• 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 (helicopters)
Zenoah G62 (large scale airplanes)	CY 26cc Marine Engine (boats)	Zenoah G231PUM / G260PUM Marine Engine (boats)

HIGH PERFORMANCE

· There are lots of different engines available for large scale RC. How fast are they, and how can I choose the right one for me?

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'.

Engine	Brand	Size	Horsepower	Recommended Fuel Octane (R+M/2) Method	Recommended Oil Ratio
G230RC	Zenoah	22.5 cc	2.8	91 octane or higher	25:1
G260RC	Zenoah	25.4cc	3.0	91 octane or higher	25:1
G62PU	Zenoah	61.5cc	5.0	87 octane or higher	25:1
CY23RC	Chung Yang	22.5cc	2.5	91 octane or higher	25:1
CY26RC	Chung Yang	25.4cc	3.0	91 octane or higher	25:1
CY27RC	Chung Yang	26.9cc	3.25	91 octane or higher	25:1
CY29RC	Chung Yang	28.9cc	3.5	91 octane or higher	25:1
GP290	Chung Yang	28.5cc	3.5	91 octane or higher	25:1

· 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 these engines.

· How much power does my engine have?
Click here to check out some dyno results for stock Zenoah engines in this factory PDF.

• 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 your engine. 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 MAX RPM 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 ENGINE PROPERLY.
  
  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.
  
  Here is some helpful information regarding common carburetor tuning problems:
  
  If your engine stutters at full throttle and cannot reach full RPMs: 
  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 idle:
  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 necessary.
  
  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 engine:
  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:
  Champion R27C
  NGK CR8HVX
  NGK CR8HSA
  NGK CR7HVX
  NGK CR7HSA
  NGK CMR8A
  NGK CMR7A
  
  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 gasket.
  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 ones.
  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 break-in my 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 procedure:
  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 "heat cycles".
  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 how:
  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 itself well.
  
• 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.
  Another approach 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 follows:
  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 second.
  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 per hour.
  Almost there...
  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.