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R/C Tips & Tricks Section

Motor Care
Engine Break-In
Engine Tuning
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Motor Care


1) Remove the motor from the car before you clean it.

2) Remove the springs from the endbell and take out the brushes.

3) Slide a commutator cleaning stick into the brush hood, appy moderate pressure, and turn the armature over several times using the pinion gear. Continue until the comm looks shiny and gold. (The comm is the part of the armature the brushes contact inside the endbell)

4) Take out the comm stick and insert the motor cleaner straw. Spray into the motor at several angles while turning the armature until the runoff is clean and clear.

5) Check the bushings/bearings (depending on motor type) on either end of the motor for buildup of dirt. Use motor cleaner if necessary.

6) Put ONE drop of bushing/bearing oil in each side. (more than one drop will attract excess dirt)

7) Install new brushes and put the springs back on. Reclean motor every 5-10 runs.

Motor Care
Engine Break-In
Engine Tuning
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Engine Break-In


On most of the engines we sell, there are three basic carburetor adjustments: the high-end needle, the low-end needle, and the idle screw

The trick to successfully operating a nitro vehicle is knowing when and how to adjust these screws.



The idle screw:      The easiest adjustment on the carb, the idle screw controls the car's idle speed. It limits how far the carb can close it's intake gap. Tightening the screw widens the gap and increases idle speed. Generally, the idle screw should be set with a 1mm gap when the throttle is fully closed.

The high-end needle:      The high-end needle is the most often adjusted needle. It regulates fuel flow to the engine at all times. Adjusting the high-end needle affects the engine's entire RPM range, including top speed and acceleration.

The low-end needle:      The low-end needle adjusts the fuel flow during idle and low RPM. Adjusting the low-end needle has no effect on top speed. Adjustments made to the high-end needle will affect the low-end needle, but not vice versa.

                            Why should you break an engine in?

     Failure to break-in your engine will cause damage to your piston and sleeve and the engine will eventually be difficult to start. The first few minutes of the life of the engine are it's most critical.

     You should always follow the break-in procedures that are included with your engine. This guide is to be used as an additional supplement to the manufacturer's procedure.

     Before you start, ensure that your glo-igniter, radio, and receiver pack all have fresh or fully charged batteries. You should also have at least two extra glo-plugs, a new bottle of 20% nitro fuel, and a fairly large area to run in. It is also helpful to have a friend around to assist you.

     Engines usually have between one and three needle valves on the carb. Nearly all cars carried by Hobby Haven have two needles, and that is what will be covered in this guide. If your engine does not have two needles, the break-in required may be slightly different from these instructions.

     Before beginning this process, be sure to read the manual included with the engine along with this guide. Also, locate the needles on the carburetor. They will usually be set for break-in from the factory, but be sure that it is set properly.

     In order to start your engine, you may need to prime the carb. The easiest way to prime an engine in by placing your finger over the exhaust hole in the tuned pipe (the 'stinger') and turning the engine over until you see fuel shoot up the line from the tank to the carburetor. Be careful not to over-prime the engine because it could result in flooding.

     If the engine does flood, or hydro-lock, remove the glo-plug and turn the engine over while the car is upside-down. This should clear the excess fuel from the combustion chamber.

     Most pre-built car engines come with a pull-starter. Be sure not to pull the starter cord out more than eight inches. If the engine doesn't start in 10-15 pulls, stop to check for the cause. If the glo-plug is good, the engine should at least "pop" and sound like it wants to start. If your engine is getting plenty of fuel through the carb and it still won't start, try turning the low-end needle in 1/8th of a turn and try again. If you try this process a few times, and the engine still doesn't start, try a new glo-plug (even if your current one looks fine). When the engine starts, it should still be very rich.

     If your engine is running at fairly high RPM or if you do not see fuel and oil coming from the exhaust when you 'blip' the throttle, the engine is probably too lean. Turn the low-end needle out until the engine is running very rich. Remember that carb adjustments do not take effect instantly. Allow 10-15 seconds for the change.

How to break-in your engine:

     After you have the engine started and running fairly rich, drive your model back and forth at about half throttle. Do this for the first four tanks of fuel and be sure to keep an eye on the engine temperature. It should be hot but not hot enough to boil water on the head. If you have a temp gun, run your engine at about 180-200 deg. After each tank, let the engine cool to room temperature.

     Repeat this process for the fifth and sixth tank (you may break-in for more than six tanks, but it is usually not necessary), but you can start tuning in the engine at this point.

     NOTE: You may want to move the piston to the bottom of the sleeve while cooling. This will give the engine more compression after it is broken-in, making it harder to turn over, but it will also increase the power of the engine. To put the piston at the bottom of the sleeve, turn the flywheel 1/2 a rotation from full compression.

Additional Information


     If the engine won't start, check the glo-plug with your glo-igniter. It is not uncommon for them to foul out during break-in. If it is fine and you have fuel flowing to the carb, lean the high-end needle an eighth (1/8) of a turn. BE CAREFUL NOT TO LEAN OUT THE ENGINE TOO MUCH!

     To kill the engine: if the car is idling, use your finger to firmly touch the flywheel on the underside of the chassis. Otherwise, you may cover the stinger or the air intake on the carb with your finger.

Motor Care
Engine Break-In
Engine Tuning
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Nitro Engine Tuning


     First, get the car up to operating temperature. Starting at factory settings, do some high speed passes. Did the car reach its top speed? You should be able to hear the engine 'clear out' at high speeds and sound clean and smooth. If it does not, lean the high-end needle 1/8 turn, let the carb settings take effect (about 10-15 sec), and then try another pass. Do this until the engine clears out at top speed.
If the engine sounds like it's starving for fuel or loses power at high RPM, the high-end needle is probably too lean. Richen the high-end needle 1/4 turn and then repeat the above process.

     Now to set the low-end needle. Let the car idle for three seconds and then punch the throttle. Did the car accelerate off the line without 'bogging down?' If not, lean the low-end needle 1/8 turn, run the car for about 20 sceonds to let the carb settings take effect, and try again. You should be able to get the car to jump off the line with little hesitation.

     You should always keep an eye on the temperature of your engine, especially while tuning. If you do not have a temp gauge, you can use the 'spit test.' Since spit has about the same boiling point as water, 212 F, how the spit reacts to the engine's head is a great indicator of the engine's temperature. If your spit has little reaction, you are under 212. If it sizzles and evaporates in only a few seconds,the temperature is too high. At best, you want the spit to sit there and slowly simmer for several seconds.

     The other thing to watch for is smoke. The amount of smoke coming from the exhaust will depend on your fuel brand, but all fuels should smoke during acceleration. If your engine does not, it is probably too lean and should be readjusted.

     Please note that nitro engine tuning is not an exact science, and there is no instruction manual that can replicate the usefulness of experience. I've found that 'if in doubt, change your glo-plug.' Just be sure to take your time, follow the instructions included with the car, and, coupled with the preceding information, you should be able to conquer the beast of nitro engine tuning.

     Keep in mind that it's always better to be too rich than too lean.

     An engine can be an expensive thing to ruin. If you are unsure about something in this section, contact the Hobby Haven car dept. using the information below...

     If you have problems or questions, contact the Hobby Haven Car Dept. at 515-276-8785 or 800-697-1213 (toll free) or hhaven@hobbyhaven.com

Motor Care
Engine Break-In
Engine Tuning
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This page was last updated: Wednesday, November 14, 2012
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