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Traxxas TRX 2.5R Owner's Manual
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Traxxas TRX 2.5R Owner's Manual

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Summary of Contents for Traxxas TRX 2.5R

  • Page 1 ™ OWNERS MANUAL ®...
  • Page 2 Entire contents ©2004 Traxxas. Traxxas, TRX 2.5R, Top Fuel, and Ready-To-Race are trademarks or registered trademarks of Traxxas. Other brand names and marks are the property of their respective holders and are used only for purposes of identification. No part of this manual may be reproduced or distributed in print or electronic media without the express written permission of Traxxas.
  • Page 3 Before running your TRX 2.5R Racing Engine, look over this entire manual and TRX 2.5R Racing examine it carefully. If for some reason you decide the TRX 2.5R is not what you wanted, do Engine Illustrated not continue any further. Your hobby dealer absolutely cannot accept a TRX 2.5R for return Terms to Know or exchange after it has been run.

  • Page 4: Safety Precautions

    SAFETY PRECAUTIONS Safety Precautions All of us at Traxxas want you to safely enjoy your new TRX 2.5R Racing Engine. Operate your TRX All instructions and 2.5R sensibly and with care, and it will be exciting, safe, and fun for you and those around you.
  • Page 5 TRX 2.5R The TRX 2.5R is designed to be tolerant of variations in tuning and running through a than in many aftermarket wide range of variable atmospheric conditions, such as changes in temperature, humidity, manufacturer’s so-called...
  • Page 6 TRX 2.5R ILLUSTRATED TRX 2.5R Racing Engine Illustrated Air Filter Head Protector Base ™ PowerTune Head (Cylinder Head) Pull Starter Idle Speed Screw Air Filter Housing High-Speed Needle Fuel Intake Air Intake Optional Backplate Carburetor Low-Speed Flywheel Needle Crankshaft Crankcase...
  • Page 7 .15 - .15 or “15” refers to the size of the engine. slide carbs and barrel carbs. The TRX 2.5R The TRX 2.5R is .15 cubic inches or 2.5 cubic uses the superior slide carburetor design. centimeters (cc). The name “TRX 2.5R” is Clean-out - Cleaning-out is a condition that derived from the cc measurement.
  • Page 8 Fuel - (10%, 20%) The TRX 2.5R must have ™ Cylinder head (head) - The finned aluminum model engine fuel to run. Traxxas Top Fuel part on top of the engine that is responsible is recommended.
  • Page 9 Usually measured as a trigger is at neutral. percentage of the total fuel volume. Traxxas Idle speed screw (ISS) - Located on the engines are optimized to use 10-20% nitro.
  • Page 10 On a than the barrel carburetor design. Traxxas model this is done by holding your Stall - When the engine stops running, usually finger over the exhaust tip for one or two due to an incorrect fuel mixture setting or seconds while the engine is starting.
  • Page 11 THE FUEL The Fuel Use the Right Fuel It’s imperative that you use the correct fuel in your TRX 2.5R for maximum performance and engine life. Traxxas Top Fuel ™ should be used to ensure correct engine lubrication, performance, and ease of tuning. Traxxas Top Fuel has been proven in thousands of engines, so you can count on it every day for great performance.
  • Page 12 • Read and follow the safety precautions on page 4 in this manual. The Air Filter The TRX 2.5R air filter is carefully designed to deliver maximum performance while protecting your engine from dust and dirt. Use only the supplied filter. You will not improve engine performance by switching to an aftermarket filter, and you may risk engine damage due to poor filtration.
  • Page 13 4. Thoroughly dry the parts with a clean towel or compressed air. Remember to wear your safety glasses when working with compressed air. 5. Oil the foam element with foam filter oil. Use the supplied Traxxas filter oil (part# 5263) or a If foam filter oil is not...
  • Page 14 The tuning needles are there have been lost. to adjust how much fuel is made available for the carburetor to mix with the available air (atomization). TRX 2.5R • 14...
  • Page 15 (Controls Fine Flow) Low Speed Needle throttle (WOT). Two needles on the TRX 2.5R provide precise control of the air/fuel ratio across the engine’s entire RPM range. The maximum possible fuel flow is always controlled by the high-speed needle. It works like the main water valve on a garden hose.
  • Page 16 Always use the idle speed adjusting screw to control engine idle. Do not use the throttle trim on the transmitter to adjust idle speed. The idle speed should be set as low as possible and still maintain reliable running. TRX 2.5R • 16...
  • Page 17 They will disappear once your engine is fully broken in. Many for information on clearing owners report not experiencing any of these symptoms with the TRX 2.5R Racing Engine. We a flooded engine. recommend replacing the glow plug with a new one after the engine break in procedure.
  • Page 18 This could result in a burned glow plug or extremely high engine temperatures. • Do not attempt to break in the TRX 2.5R Racing Engine by idling it on a stand. This will produce poor results.
  • Page 19 6. Proceed with the engine break-in. As you gain experience in the hobby, you may If your engine doesn’t start, refer to the TRX 2.5R Racing Engine troubleshooting section discover that many people at www.Traxxas.com. If you still have problems, contact Traxxas Customer Support at have differing opinions on 1-888-TRAXXAS.
  • Page 20 BREAKING-IN THE TRX 2.5R Tank 3 1. Driving procedure: Gently pull the throttle trigger to 1/2 throttle over a 3-second count. Then gently apply the brake to stop. Count the three seconds out while accelerating: one thousand one, one thousand two, one thousand three, and then stop. Repeat this starting and stopping procedure until the third tank of fuel is nearly empty.
  • Page 21 • After the engine is running, it is important to keep the temperature of the engine to at least 200 to 215 degrees during break-in. In weather below 45 degrees, the TRX 2.5R Racing Engine will tend to run at lower temperatures between 160 to 180 degrees (when tuned at proper break-in mixture settings).
  • Page 22 Tuning Your TRX 2.5R Racing Engine The engine’s performance depends on the fuel mixture. Turn the mixture needles clockwise to lean the fuel mixture and counterclockwise to richen it. Leaning the fuel mixture will increase engine power up to the engine’s mechanical limits.
  • Page 23 1/16 turn increments. Make several high-speed passes after each adjustment to clear out the engine and note any change in performance. The TRX 2.5R is extremely powerful. Remember to apply the throttle gradually to prevent wheelies or loss of control. Continue this procedure until there is no longer any performance improvement.
  • Page 24 TUNING THE TRX 2.5R 3. There is a sudden loss of power during acceleration (Danger!) 4. The engine begins to overheat. Symptoms of overheating include: For your convenience, the • Fluctuating idle speed • Popping or clattering sound when low-speed needle has a •...
  • Page 25 4. Reset the throttle trim on the transmitter to its original position. Fine-Tuning the Carburetor After fine-tuning your TRX 2.5R Racing Engine at the end of the break-in procedure, no major adjustments to the fuel mixture are usually necessary. Make note of the temperature, humidity, and barometric pressure at the time you finished fine tuning your carburetor.
  • Page 26 Tuning the Engine by Temperature The following procedures require an optional infrared temperature probe or on-board temperature gauge (Traxxas on-board digital temperature gauge, part #4091). Engine temperature can be used as an effective tuning aid when you understand the relationship between engine temperature and ambient temperature.
  • Page 27 TRX 2.5R Racing Engine. Most questions arise from simple user errors or minor adjustments that are easy to correct. If you can’t find a solution for your TRX 2.5R Racing Engine here, visit our web site at Traxxas.com and click on the Customer Support menu. There you will find a much more extensive and detailed online troubleshooting area.
  • Page 28 1/4 turn and then retune the engine for performance (see page 22). • Try a new Traxxas glow plug. Sometimes a glow plug will work well enough to start the engine but not be able to deliver the engine’s full performance potential.
  • Page 29 • If the fuel mixture seems to be set correctly, make sure the fuel is fresh. If the fuel is old, or was left uncapped for a long period, then some of the important fuel components could have evaporated. Try new, fresh, Traxxas Top Fuel. • Check to make sure there is no binding in the driveline that would cause excessive loads on the engine.
  • Page 30 MAINTAINING THE TRX 2.5R Maintaining and Storing Your TRX 2.5R Racing Engine TRX 2.5R Racing Engine requires timely maintenance in order to stay in top running condition. If the engine is worn or Neglecting the maintenance could allow dirt, deposits, and moisture to build up inside damaged enough to the engine, leading to internal engine failure.
  • Page 31 WD-40 ™ , a common household lubricant. To ensure your TRX 2.5R as the crankcase, crankshaft, Racing Engine is protected from internal corrosion, use the following procedure: and engine bearings are made to extremely high Whenever possible, shut off the engine by pinching the fuel line closed.
  • Page 32 Replace the wrist pin and G-clip whenever the piston and sleeve are replaced. Follow the instructions for the proper break-in procedure of a new TRX 2.5R Racing Engine whenever the piston and sleeve are replaced.
  • Page 33 Rebuilding the TRX 2.5R Racing Engine These instructions are for the rebuilding The following instructions are for engines equipped with IPS crankshafts using Traxxas of the Traxxas TRX 2.5R engine once the clutch components. For multi-shaft ™ engine has been removed from the crankshafts in non-Traxxas applications, chassis.
  • Page 34 REBUILDING THE TRX 2.5R this temperature. Use gloves to 3. Remove the glow plug from the protect against burns. ) Rotate the cooling head and discard the plug. crank to where the rod and piston are The glow plug should be replaced...
  • Page 35 (601). the piston, sleeve and connecting rod it may Caution: Do not let the compressed air be best to take advantage of the Traxxas spin the bearings and always use eye Engine Replacement Program. protection when using compressed air.
  • Page 36 REBUILDING THE TRX 2.5R 10. Lube the outside of the piston 9. Apply a drop of after-run oil in the 1002 piston’s wrist pin bore, before installing with after-run oil and make sure the Skirt Relief the wrist pin. Locate the oil hole (refer to...
  • Page 37 Install a new glow plug (Traxxas #3232 clutch bell over the pilot shaft followed is recommended for the TRX 2.5R) into by the 5x8x0.5TW (1401). the cooling head. The engine is now Fasten the 5.0 E-clip (wearing safety...
  • Page 38 3x15CS screws (1601). The engine, clutch, exhaust system 1602 and starter assembly is now ready for installation into the chassis (1602). Follow the instructions for the proper break-in procedure of a new TRX 2.5R Racing Engine. TRX 2.5R • 38...

  • Page 39: Troubleshooting

    Speed Adjustment” Clean-out; 7 by temperature; 26 ratio; 14 Clutch Bell; 6 fine-tuning; 24 rich; 10, 15, 16 Combustion chamber; 7 Wear-in; 10 Glow plug; 8 Connecting rod; 7 WOT; 10 driver; 9 Cooling fins; 8 TRX 2.5R • 39...
  • Page 40 ® 1 1 00 Klein Road, Plano, Texas 75074 1-888-TRAXXAS 051007...