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QuickStart: Nitro Gas Powered Vehicles

Instructions on how to break in / tune your nitro gas vehicle.  Download 
You Got the Box Open. Now What?
Starting Your Nitro for the First Time
Engine Break-In Procedure
Engine Tuning
You Got the Box Open. Now What?
There once was a time, when assembling an RC kit was a rite of passage for anyone who wanted to experience the excitement and fun of running a "real" RC car. But with the proliferation of ready-to-run (RTR) options, this time honored tradition has now become optional. Although the construction quality of these vehicles is superb, there is still some minor work that needs to be done. The purpose of this article is to help anyone who has just purchased a nitro get acquainted with their new vehicle. Be prepared to learn everything from initial set-up to performance tuning. Whether you’re a veteran or a beginner, this guide will get you on the road (or off it, if that’s what you prefer) in no time.

Important Note: During the break-in process, the engine may seem like it's stalling or not running properly. This is normal. Your car is not malfunctioning. This is part of the break-in process. Moreover, it is normal to have to replace glow-plugs after the break-in process due to the deposits left behind during the break-in. Since glow plugs are a normal item that need replacing, and play a large part in determining how the engine will run, we recommend our customers always have a few spares on hand.

Our manufacturers implement stringent quality control measures in order to eliminate defects. Although rare, defects do occur. By verifying the operation of the servos and remote, it allows us to identify and replace any defective items before any damage can arise from use of a defective item. As such, any defective items (i.e. faulty servos etc.) will be replaced. However, any damage (crashed or broken parts) arising from the use of defective items is not covered under warranty and is the sole responsibility of the owner, because normal operating procedure requires users to verify the proper operation of these items, prior to operation.
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Starting Your Nitro for the First Time
  • Step 1. Charge the igniter.
    In order to start your nitro vehicle, you will need to charge the glow plug igniter. Attach the glow plug igniter to the charger, and plug the charger into the outlet. Charge the glow plug igniter for 4 - 5 hours. Troubleshooting: If you have tried several times to start the engine without any success, you may have to recharge the glow plug igniter, as a weak igniter will not have the necessary voltage to ignite the nitro fuel.

  • Step 2. Install the radio system batteries.
    Install batteries into both the transmitter and the RC vehicle. Be sure to use only high quality batteries.
    Caution: Weak or dead batteries can cause you to lose control of your RC vehicle.

  • Step 3. Turn on the transmitter and receiver.
    Always turn on the controller [First] and the receiver [Second].
    Caution: This rule of thumb will prevent you from losing control of your RC due to stray radio signals.

  • Step 4. Check operation of the radio system and servo.
    Caution: Checking the radio system is probably the most important thing one can do prior to starting their nitro vehicle. A malfunctioning radio system can potentially result in severe damage. It is important that you perform a radio check every time you take your nitro vehicle for a run.

    Begin by lifting the front tires off the ground. Now, turn your transmitter wheel left and right to verify that the servos that control the steering are functioning properly. If operating properly, once the "wheel" is released, the front wheels should automatically return to the neutral position.

    It is now time to check the engine throttle. To check the throttle, pull back on the trigger. If operating properly, the carburetor throat should open.
    Note: Make sure the servo returns all the way to the pre-set position once the trigger is released.
Wheel Check
Center Right Left

Throttle Check
None Middle Full Throttle

  • Step 5. Perform a range check.
    Before starting, make sure to fully extend the antenna on the transmitter. Also, check the wire antenna on your RC and be sure that it has been uncoiled. Use the antenna tube to properly mount the antenna onto the body of the receiver. Now, while leaving your vehicle in place, walk a good distance away (however far you plan on operating your RC from) from your RC. From this distance, verify that your servos are still operating properly.

    Troubleshooting: There are a number of factors that can cause radio signal interference. These include, but are not limited to, power lines, metal beams, large outdoor antennae, fluorescent lights, and even computer monitors. If you think you radio system may be faulty, try another location, as radio interference may be the source of your problem.
  • Step 6. Check the screws.
    Check and tighten all of the screws on the vehicle. We recommend that you apply threadlock to any screws being inserted into any metal components of your vehicle. In doing so, this will prevent any screws from loosening due to engine vibration. Remember to pay extra attention to the four engine screws pictured on the left.
    Threadlock can be purchased at your local hardware or automotive store.

  • Step 7. Adjust the fit between the spur gear and clutch bell.
    Loosen the four engine screws, allowing the engine to slide back and forth. Then, place a small ¼ inch by six inch wide piece of paper between the spur gear and clutch bell. Push the engine towards the spur gear (as pictured), then tighten the bolts and remove the paper.

    To verify a proper fit, place one finger on the spur gear to hold it steady and check for a tight fit between the gears. It should not be too tight, though. When the car is pushed gently, it should move freely.

    Note: The clearance between the differential gear and the clutch bell must be 0.1mm. A clearance of greater than 0.2mm will negatively affect the performance of your vehicle.
    Caution: An improperly fitted spur gear can not only affect performance, but cause damage to your transmission as well.
  • Step 8. Fill the tank with fuel and prime the engine.
    We recommend you use 20% nitro fuel when first fueling your vehicle. Begin by lifting the lid on the vehicle's fuel tank and inserting the fill tube. Slowly squeeze the fuel bottle and fill the tank until full. Be careful not to overfill the tank. To prime the engine, place your finger over the exhaust and gently pull the pull start until you see fuel entering the fuel line into the carburetor.
    Note: Some RCs come equipped with a fuel primer on the fuel compartment. If so, push the fuel primer until you see fuel entering the carburetor.

    Troubleshooting: Be careful not to over prime the engine, as this may result in a flooded engine. Although an easy fix, this will prevent the engine from starting. See Clearing a Flooded Engine for more information.
  • Step 9. Perform a visual check for obstructions.
    Check the nitro vehicle for any potential obstructions that may prevent proper operation of your RC. Make sure there are no hoses, wires or any other obstructions interfering with the moving parts of your RC. For example, pictured below is a fuel hose which was punctured by the spinning spur gear. This was replaced with a new hose and secured in place to prevent future complications.

  • Step 10. Fire it up.
    When starting the engine, do not place the vehicle directly on the ground. Instead, place the vehicle on top of a block so the wheels are not in direct contact with the ground. This will prevent the vehicle from taking off unexpectedly from stray radio signals.
    Pull back on the glow plug igniter and insert it into the glow plug chamber until it clicks, then let go of the grip to attach the glow plug igniter to the glow plug. Once the igniter is attached, pull the pull-starter with short, quick pulls until the engine fires. Once started, remove the glow plug igniter by pulling back on the grip and removing the igniter.

    Troubleshooting: If you engine locks up during the start up process, do not be alarmed, as this is relatively normal for a brand new nitro engine. This is caused by one of two things, a flooded engine and/or a mechanically stuck engine. Both of which are discussed below.

    Clearing a Flooded Engine - If, during the "firing" process, the cord become hard to pull, the engine may have become flooded.
    • 1. Disconnect the glow plug wire from the glow plug if present. Proceed to remove the glow plug from the engine using a two-way 5/16" nut driver.
    • 2. Turn the nitro vehicle upside down and quickly pull the pull start a few times. This should turn the engine over at a rapid rate, causing any excess fuel from the combustion chamber and crankcase to be drained. If, after several pulls from the starter, there is still fuel coming out of the engine, continue this process until all the fuel has been drained from the crankcase.
    • 3. Be careful to wipe away any raw fuel from the cooling head with a clean rag and reinstall the glow plug. When installing the glow plug, make sure to install the copper glow plug gasket correctly before installing the glow plug.
    For more detailed instructions and pictures regarding this process, see Clearing a Flooded Engine.

    Loosening the Engine – Brand new nitro engines have a tight fit between the piston and the sleeve. However, this tight fit, should not be so tight that it prevents the starting of the engine. If the engine is stuck, simply follow these simple steps to loosen it.
    • 1. Make sure the engine is not flooded. A flooded engine has some of the characteristics of a stuck engine. See above.
    • 2. Locate the flywheel on your RC. It is usually visible from underneath the vehicle frame. Simply wedge a screwdriver into a groove on the flywheel and, using the frame as a leverage point, rotate the flywheel a couple times.
    • For more detailed instructions and pictures regarding this process, see Loosening the Engine.

    It's now time to start the break-in process. This consists of starting the engine and following the recommended operating guidelines for each fuel tank.

    Radio interference is invisible, and can pose as an unseen danger. If there are no stray signals in your area, you can take your vehicle off the block and proceed with the break-in process. At the end of each tank, there will be a short cool down period of 10-15 minutes before refueling, restarting the engine, and progressing to the next tank. At the end of the 5th tank, your engine will be properly "broken-in" and will be ready for engine tuning. This will allow for efficient, high-speed racing.

    Troubleshooting: The carburetor is preset at the assembly factory for optimal break-in. Please use the pre-set settings as a starting point for the break-in process. However, if for some reason you are having trouble starting or keeping the engine running, please adjust the fuel mixture according to the guidelines outlined below.
Engine Break-In Procedure
The purpose of the break-in procedure is to thoroughly prepare the engine and its components for consistent and lasting performance. In order to allow for a smooth break-in, we recommend you follow these operating guidelines outlined for the first 5 tanks of fuel.

Caution: High speed running is not recommended until the engine has been broken by using the 5 tank guideline outlined below. Failure to do so can result in permanent engine damage.
Once broken-in, you will need to "tune" the engine by adjusting the carburetor settings, which is also outlined in this manual. This will allow the nitro vehicle to operate efficiently, as well as maximize its performance capabilities giving you the most out of your RC.

Things to keep in mind during the break-in procedure :

  • Fuel Level: Be mindful of the fuel level. Allowing the vehicle to run on an empty fuel tank can result in a damaged fuel plug or engine damage caused by high engine temperatures.
  • Location: It is advised that the break-in procedures be performed on a flat and clean surface since this part of the break-in procedure will be performed without the car body. This environment will minimize dirt build-up and accidental damage that may occur without the body present.
  • Throttle Control: Braking and throttle should be applied gently. Sudden breaking and acceleration may cause the engine to stall and increase the chances of damaging the RC vehicle.
  • Batteries: Before operating your nitro vehicle, check the strength of the batteries in both the receiver and controller.

Tank 1 – Guidelines

  • Body: Drive the vehicle with the body removed. This will allow for proper cooling.
  • Driving Procedure: Gently pull back the throttle to the ¼ position, over a 2 second count. Then, gently apply the brake to stop. Repeat this "start and stop" procedure until the first tank of fuel is nearly empty.
  • Signals: If there is a nice trail of smoke coming from the exhaust, then your engine is being lubricated and the fuel mixture is properly set. If this smoke is absent, richen the high speed fuel mixture a ¼ turn counterclockwise until the smoke is present.
  • Shutdown: Shut off the engine by pinching the fuel line to the carburetor. Before your next tank, let the car cool down for 10-15 minutes.

Tank 2

  • Driving Procedure: Gently pull back the throttle to the ½ position over a 2 second count. Then, gently apply the brake to stop. Repeat this "start and stop" procedure until the second tank of fuel is nearly empty.
  • Shutdown: Shut off the engine by pinching the fuel line to the carburetor. Before your next tank, let the car cool down for 10-15 minutes.

Tank 3

  • Driving Procedure: Gently pull back the throttle to the ½ position, over a 3 second count. Then, gently apply the brake to stop. Repeat this "start and stop" procedure until the third tank of fuel is nearly empty.
  • Idle Speed Adjustment: As the engine loosens and the break-in procedure progresses, the idle speed may increase, causing the car to move forward without any input from the throttle. If this occurs, you may have to reduce the idle speed by turning the idle adjustment (underneath the oil filter) on the carburetor counterclockwise until the car no longer moves on its own.
  • Shutdown: Shut off the engine by pinching the fuel line to the carburetor. Before your next tank, let the car cool down for 10-15 minutes.

Tank 4

  • Driving Procedure: Gently pull back the throttle to the full position, over a 3 second count. Then gently apply the brake to stop. Repeat this "start and stop" procedure until the fourth tank of fuel is nearly empty.
  • Always make sure to apply the throttle slowly. Keep your driving smooth and consistent.
  • Shutdown: Shut off the engine by pinching the fuel line to the carburetor. Before your next tank, let the car cool down for 10-15 minutes.

Tank 5

  • Driving Procedure: Gently pull back the throttle to the full position, over a 3 second count. Then, hold for 2 seconds, and gently apply the brake to stop. Repeat this "start and stop" procedure until the fifth tank of fuel is nearly empty. Shut off the engine and refuel. It is now time to "tune" the engine.
  • Shutdown: Shut off the engine by pinching the fuel line to the carburetor. Before your next tank, let the car cool down for 10-15 minutes.

Tank 6

At this stage, the engine is now "broken in." It is now time to tune the engine for general performance.
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Engine Tuning
The first and foremost consideration when attempting to tune your glow engine is to understand the basic parts of a nitro vehicle and their functions.

The main function of the carburetor is to create a proper mixture of fuel and air. Once this mixture is achieved, it is sent to the engine to be combusted. The carburetor can be adjusted to control the mixture ratio of gas to air that is fed into the engine. If you increase the amount of fuel in the mixture, you are making the mixture "rich" and alternatively, if you decrease the amount of fuel in the mixture, you are making the mixture "lean".

An engine's performance is dependent upon this fuel mixture and is regulated by the carburetor, which, in turn, is regulated by a high speed, low speed, and idle speed setting.

Important Note: Make sure to completely break-in your nitro engine prior to tuning the engine for maximum performance.

Important Note: Turn the mixture needles clockwise to create a “lean” mixture and counterclockwise to create a “rich” mixture. A lean fuel mixture will increase engine power, but be wary.

Caution: Never run an engine too lean, because it will cut out or begin to stall. This could cause severe engine damage.

In order to tune your RC for performance, start with a rich fuel mixture and slowly move towards a lean mixture until the ideal mixture ratio is found.

Caution: Never EVER tune from a lean to a rich mixture. There should always be a light stream of smoke coming from the exhaust.

You can tell an engine is running rich by observing any of the following:
kLeaning the high speed fuel mixture increases performance
kSluggish acceleration
kUnburned fuel spraying from the exhaust tip

  • Step 1. High Speed Fuel Mixture Adjustment
    This is primary fuel mixture adjustment. It is located next to the air filter, where the fuel line connects to the engine.

    After the engine is warmed up, gradually lean the high speed mixture by turning it in 1/16 increments clockwise until an ideal mixture is reached. Make several passes with the RC after each adjustment and note any changes in performance.
    If you "lean" your mixture too much, one or more of these things may occur:
    Fluctuating idle speed
    Temperature measurement above 270F at the glow plug
    Little or no smoke from the exhaust
    Noise or clattering sound during deceleration
    Sudden cutting of power during acceleration
    Smoke or steam form the engine (not exhaust)
    Hesitation or stalling during acceleration

    If you are experiencing one or more of these symptoms listed above, slowly richen the mixture by giving the high speed adjustment 1/16th turns counterclockwise until the symptoms disappear.
  • Step 2. Low-Speed Fuel Mixture Adjustment
    The low speed mixture adjustment is performed only after the high speed needle has been correctly adjusted. The easiest way to adjust the low speed mixture is by doing the "pinch" test. The valve is located where the throttle arm pivots.
    Pinch” Test
    Having set the high speed needle correctly, take the RC vehicle and pinch the fuel line going into the carburetor. The engine should run for about 2-3 seconds, speed up, and die.
    If the engine runs longer than 3 seconds, give the low speed needle a 1/16 turn clockwise. Run the vehicle again and retest. Repeat as necessary.
    If the test results in the engine dying immediately, without speeding up, richen the low speed needle by giving it 1/8 turn counter clockwise. Run the vehicle again and retest. Repeat as necessary.

    Once the low speed needle is correctly adjusted, the engine throttle should respond very quickly. It is now time to adjust the idle speed.
  • Step 3. Idle Speed Adjustment
    This spring tensioned screw is located beneath the oil filter, facing towards the front of the vehicle.

    In order for an engine to run, it must have enough internal inertia built up in the engine to catalyze the entire ignition cycle. Generally speaking, you want to adjust the idle speed to the slowest idle possible, just before it starts to stall. The key is to set the idle speed as low as possible while still maintaining reliable running characteristics. In order to do this, turn the idle screw counterclockwise to reduce the idle speed. If your engine stalls or cuts out, turn it clockwise to increase it. Remember, the goal is to reach the point that is just before the point where the engine stalls and cuts out.

This chart indicates the direction in which you should adjust the fuel mixture when faced with changing conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in this chart. Knowing how to adjust the fuel mixture is a crucial part of operating and maintaining your RC vehicle.

Higher Air Pressure Lean
Lower Air Pressure Rich
Higher Humidity Lean
Lower Humidity Rich
Higher Barometric Pressure Rich
Lower Barometric Pressure Lean
Higher Altitude Lean
Lower Altitude Rich
Higher Nitro Content Rich
Lower Nitro Content Lean
Higher Oil Content Lean
Lower Oil Content Rich
Hotter Glow Plug Rich
Cooler Glow Plug Lean

After breaking in the engine and tuning the engine, no major adjustments should be necessary. It's now time to run your brand new nitro vehicle. If you experience any other issues with your nitro RC, see here: Troubleshooting Your Nitro Vehicle.

We hope you found this information useful and enjoyed our easy to use tutorial guide. For more tutorials, how-to guides, FAQs, and much more, please visit our Learning Center at

Copyright © The Xenon Project, LLC. Any duplication, copying, or use without prior written consent is illegal.

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