Help With Nitro Engines


Before using any Nitro Engines it is important that you check the following:

* Receiver Battery
* Range check (Stand a distance away from the model and make sure it is responding to the radio control correctly. Ideally do this with someone else so you can stand as far away as you want to use the model.
* Radio Battery
* Glow Plug is tight and glow start is fully charged
* Ensure engine flywheel is tight and tighten if needed (IMPORTANT OR THE FLYWHEEL WILL WEAR AWAY)
* Loctite/tighten any loose nuts, screws or bolts. ie: set screws, engine mount screws, wheel nuts, etc
* Clutch-bell and Spur Gear mesh (IMPORTANT OR YOU WILL STRIP YOUR GEARS)
* Pullstart engine screws
* Nylon ties for exhaust
* Clean & Re-Oil or replace Foam Air Filter element
* Ensure all servo & throttle linkage is straight at 90 degrees & in proper alignment when the radio equipment is turned on. Adjust if needed.
* Ensure fuel system is free of obstruction, line pinches, dirt & leaks
* Clean entire car after every tank – watch for sand, rocks, mud, debris or anything that will hinder proper operation and maintenance.

The above maintenance should be observed ideally after every run.

The main adjustment screw would have been pre-set at the factory and we would have double checked it to make sure it is correct for running the engine in. In 99% of cases this screw will not need touching until after you have run the engine in if you wish to fine tune it. If you do loose the starting position of the screw or want to check it then the top of the screw should be just 1 – 2 mm below the top of the screw casing.


1. Fill the fuel Tank and check that the fuel lines are secure and free of kinks to ensure clear fuel flow.

2. Prime the engine with fuel by putting your finger over the exhaust or air intake and then pulling the starter until you see the fuel reach the engine. Once you see the fuel reach the engine pull the starter another couple of times to spread fuel through the engine. If it will not prime make sure all the screws around the engine and manifold are tight and that the lid on the fuel tank is closed. If it still will not prime take the end of the fuel line that connects to the exhaust off and blow down it which should force fuel into the engine.

3. Attach your glow start to the glow plug (located on top of the engine cooling head)

4. Pull the recoil starter with short quick jabs. Avoid pulling the recoil cord 100% of it’s length as this will damage the starting spring, and this is not covered by the motor’s warranty. If the pull start becomes very hard to pull then it means the engine is flooded. In this case you must NOT pull the start again until you have un-flooded the engine or else you will break it. If the engine is cold you may need to open the throttle a TINY bit just to help it start. If the engine is cold you may need to pull the start a good few times, the trick is to pull it quickly and consistently. If it is still stiff try unscrewing the glow plug half a turn and then when it starts tighten it up again.

5. If the setting are correct the engine should start. Disconnect the glow clip as soon as the engine is running.

The main needle adjustment is used to adjust the fuel to air mixture when you are accelerating. Once the engine is run in if it is spitting fuel from the exhaust you may want to turn the adjustment screw a little clockwise just a mm or so. Do not over tighten it though as this will overheat the engine and could melt the parts. When you make a change to the adjustment screw the changes will not take effect until after a couple of minutes running.

If it does not start please see our help section on what to do if your engine does not start.


The engine has to be Run-in before full-time use. It is very important that this procedure is carried out. Not doing so will shorten the life and reduce the overall performance of your engine.

There are two different methods people use to run their engines in. The first one is simpler and is also safer in that you are less likely to burn your clutch out or something if you get it wrong. With the second method it is more complicated but if done correctly will give a little more life to your engine.

To run your car in, take your finished model and roll it back and forth to be certain the car’s wheels can turn freely. Place the car in a position so that the wheels are off the ground, for example on a heavy box or brick, and follow the starting procedure which can be found on our help page. Use good quality fuel with around 10 – 20% mix. Its best to break-in the engine using the same nitro content as you plan to use for everyday use. The engine should be broken-in on a smooth hard surface. For a boat engines, try to find smooth calm water. Try to avoid breaking-in the engine on very hot, or humid days. Ensure that the idle speed is not to high or else you will burn your clutch out or snap the con rod, and also make sure that the brake is not applied.

Always break-in your engine without the body on the car, you want as much airflow as you can get to keep the engine cool. Do not run the engine too lean or you will over heat it and cause permanent damage to the internal components of the engine.

It is normal for the engine to consume a lot of fuel during break-in. This is because you are running it “richer” than you normally would to keep the engine cool and to flush out the engine as the parts “seat” themselves. Because of the richer than normal setting the performance of the engine will be limited. After break-in, you will then lean it out to gain performance.

It’s always a good idea to get an extra glow plug (short, cold plug). It is normal to have to replace it after break-in because of the deposits left on in from the break-in process. Glow plugs are a normal item that needs replacing. Because they have such a huge influence on they way your engine runs it best to always have a few spares on hand.

Method 1:

Once it starts and is idleing slowly place it on the ground and drive it slowly on a flat surface. For the first use do not let the engine run for more then 3 minutes. Carry on running slowly for short periods until you have gone through 2 – 3 tanks of fuel.

Method 2:

With method 2 start the car in the same way but when it starts instead of placing it on the ground keep it off the ground and let the engine idle through 2 – 3 tanks of fuel. Let the engine cool down in between each tank and lean the engine off as needed. Do NOT rev the engine while it is running in and be careful not to lean it off to much or else you will burn your engine which would not be covered by the warranty.

Do not over accelerate at all during this procedure, as it can severly damage the engine. After each idling time, let the car rest for about 10 minutes between each tank. Running in makes sure that the engine is operating correctly before you take it out for a proper run. Never accelerate the engine while all four wheels are off the ground, as this will break the conrod or other important components.

One important thing to remember when breaking in a new engine, it will appear to not run correctly. It will stall, operate very inconsistently, and may even foul glow plugs. Don’t get frustrated with it. Just keep working with it and it will become a smooth running engine. These experiences are what can be called “break-in pains”. Every new engine has to go through this. When you get the engine started, be sure to keep it running by giving it throttle when it sounds like it’s going to stall. Pulling the throttle quickly can also stall the engine. After a couple of tanks your patience will pay off with a very strong, reliable running engine.


It is VERY rare that a fault can be traced back to the engine. Check the following points below before considering the engine to be faulty.

1. Check the flywheel is not loose. You should not be able to turn the flywheel without also turning the engine. If the flywheel is loose you will need to tighten the flywheel bolt. If the flywheel is loose the engine will usually start but then cut out straight away.

2. Do the wheels turn when you pull the starter? If so the clutch shoes have melted and will need replacing – (part21027 on Acme 1/10th nitro models).

3. Has the Glow Plug burned out? Remove the glow plug and check if it is glowing. Do this by attaching the glow plug to the glow start directly and the coil in the bottom of the glow plug should glow bright red in a matter of seconds. Engines will not start if the glow plug is dim or not glowing at all.
Solution: Replace the battery and/or glow plug.

4. Is the recoil starter hard to pull ? If the recoil starter is hard to pull this means that the engine is flooded (there is too much fuel in the combustion chamber). At this point don’t pull the recoil starter any more – doing so will damage the recoil spring. or break the pull cord. Any misuse of the recoil starter unit will void the manufacturers warranty.
Solution : Remove the glow plug from the heat sink head and turn the car upside down. Now pull the recoil starter a few times to expell the excess fuel out of the combustion chamber. Replace the glow plug and start again.

5. Does the car start, but stalls when the glow clip is removed ? If this happens it’s a possibility that the car is idling too low
Solution: Look down at the carburettor from above. It should be all but closed, with just a 1 to 2 mm gap to allow the air in. The idle setting can be changed by turning the idle screw in or out.(The idle screw is generally located right next to the carburettor barrel)

6. Go to our help page and make sure you have carried out all the steps to pre-use and starting correctly and carefully.

7. If the engine feels tight when you pull the pull start try undoing the glow plug just a tiny bit which will release some of the pressure and then when the engine starts you can tighten it back up.

8. Make sure you have primed the engine with fuel correctly and enough. It will not start if there is not enough fuel in the engine and it will not start if there is to much. There is more info on the how to start a nitro engine section on our web site.


If you have a 2 speed model the first gear in the gearbox (the bigger one) will have a one way bearing in the middle of it. This is a bearing that sits on the gearbox shaft that will spin in one direction but not spin in the other direction. In cold or dirty conditions it is possible for one way bearings to fail as if the grease that is on the bearing gets to cold or dirty it solidifies and causes the bearing to slip. If this happens the first thing to try is to warm the gearbox up for 5 – 10 minutes using a hairdryer which will hopefully solve the problem. If it does not you will need to take the gearbox out and take the first gear off to reveal the one way bearing and shaft. Using some wd40 or similar you need to give both the shaft and the middle of the one way bearing a really good clean so there is no grease left on it at all and then re-grease it using one way bearing grease. Taking the gearbox out is easy but takes a little time. Undo the four screws on the bottom of the chassis that hold the gearbox on and then undo the screws that hold the upper chassis on. You will not be able to take the upper chassis off as the servo wire will still be connected but you will be able to move the upper chassis so that you can then get the gearbox in and out ok. Getting the drive shafts back in the drive cups is a little fiddley but if you use some pliers or something to hold them it’s not to difficult. If you clean the bearing and it still slips just let us know as it may need replacing.

Other possibilities why a nitro model may not move are:

1. The brake pads are to tight or have got wet and have expanded causing the brake to be constantly engaged. If this happens you need to loosen the brake pad screws.

2. One of the grub screws in one of the drive cups has come out or is loose. If this happens the drive cup will rotate but it will not turn the shaft. You should go round every drive cup and make sure all the grub screws are tight.

3. Something inside the differentials may have broken or come loose. You would need to open the differentials and check all the cogs inside are ok. If any cogs are worn it would be better to replace them but you can get a bit more life out of them by padding them with washers to push the cogs closer together and improve the mesh.


Q. What else do I need to run the model?
A. All our models come with the radio control and servos included and installed. All you will need to run is some model glow fuel and a standard glow start. These items are between $10 – $15 each from most model shops.

Q. How long does the fuel last?
A. A tank of fuel will last about 10 – 15 minutes. A 2.27 litre bottle of fuel should be enough to fill the tank about 30 times. The good thing about nitro models though is you do not need to wait for the to charge, you can just fill them up and keep on going.

Q. Why did my con rod break?
A. The only way that a con rod can break is either the engine is revved with no load or there is not enough fuel in the engine so there is not enough lubrication which causes the piston to jam. You should be careful not to rev the engine if the wheels are off the ground, if the flywheel is loose or if the model does a jump. Con rods are not covered by the warranty but available as a spare part.

Q. Why do my wheels turn when I pull the pull start?
A. If you are unable to pull the pull start without the wheels turning it means your clutch shoes have probably melted. This happens when the car has been incorrectly adjusted so that the brake is slightly on when the throttle is in the neutral position. They can also melt if the wheels or truck is held still while the engine is revving or if the idle speed is to high. If this happens you will simply need to purchase a new clutch shoe and replace the melted one.

Q. Why did my gears strip?
A. Stripping a spur gear (a flat spot on the plastic gear that turns the drivetrain of the car) is not caused by the spur gear or pinion gear. A stripped spur gear is caused by the pinion gear not having the correct mesh with the spur gear.

Q. How can I get correct gear mesh?
A. The easiest way to learn that you have the correct gear mesh is to use a piece of paper and fit it between the spur gear and pinion gear as you tighten the motor mount screws. After the motor is completely tightened, the piece of paper should be impossible to remove except by turning the spur gear to rotate the paper out of place. With the paper gone, turn the spur gear with a finger and feel the amount of movement or “play” there is between the spur gear and pinion gear. There should be very little play, but you should feel a little bit. This is the correct gear mesh. With practice, you will no longer strip any spur gears.
Make sure the motor mount screws are very tight, a big crash could move the motor towards or away from the spur gear, making the spur gear strip out.

Q. What maintenance will I need to do?
A. Please see the before use section on our help page for maintenance details.

Q. Why did my flywheel wear away?
A. If the bolt holding the flywheel on is not tight and you continue to use the car it will start to wear the flywheel away. You should check that the flywheel is tight before each run.

Q. My 2 speed is not shifting?
A. Unless something is not adjusted properly or broken, the 2 speed should shift into second when the engine reaches a certain speed. If it does not shift, use a 2mm Allen wrench to adjust the shift point set screws counterclockwise. Turn the set screw 1/4 turn at a time and make a test run to see if the car shifts into second. If it does not, turn the set screw 1/4 turn more and try again. Make sure not to touch the center set screw! If you look on the two speed gearbox you will see a small 5mm hole on the smaller gear. If you rotate this hole it will give access to the two shift screws. There is one on each side of the gear.

Q. Do you need a liscence to use a nitro rc car?
A. No you do not. Just use common sense and do not use them where they may disturb or injure people if they loose control.

Q. What ages are nitro radio controlled cars recommended for?
A. To do everything 14+ is best. A younger child would be able to drive them but may struggle with the setup and maintenance. We have customers as young as 8 but any younger than 14 you should be prepared to help them with the maintenance. Nitro rc cars can be a great educational toy and introduction to engineering.

Q. What kind of range does it have?
A. About 100m but you should always do a range check before use.

Q. How do I stop the engine?
A. Cover the exhaust hole and it will turn off a second later.

Q. What fuel Do I use for nitro engines?
A. You need to use model glow fuel. We sell this under accessories and it is also sold in model shops and some Halfords stores. You can use any good branded fuel with a nitro content of 10 – 30%. For normal use 10 – 16% is best and then you can use a higher percentage for races. The higher percentage fuel will increase the speed but it is more expensive.


A glow starter is a tool that you will need to start your engine. With simple finger pressure it locks on and off the glow plug. When the glow starter is attached to the glow plug (located in the cylinder head of your engine) the wire coil on the other side of the glow plug glows to ignite the fuel in your engine.


1. Before using you may need to charge your glow starter. You should test it first to see if it has any charge in it. If flat the charging time will be written on the side of the glow start and after that you should only charge again once the glow starter has gone flat. If you over charge the glow start it will damage it.

2. To charge, in the same way you would attach the glow starter to the glow plug (see point 3 for details) insert the nut shaped charging end into the locking socket of the glow starter. Finally, plug the charger into the wall socket.

3. To lock the glow starter onto your glow plug all you need to do is place the glow starter over the glow plug and add gentle pressure pushing down with your palm while pulling the plunger up with your fingers. You should see the claws (locking socket) come out of the top of the glow starter and cover the glow plugs hexagonal body. Once covered let go of the plunger but still keep the gentle pressure down with your palm. You should feel that the glow start has locked on and when you let go it will be attached to your glow plug.


1. Never leave your glow starter attached for any long lengths of time. If you are struggling to get your engine started don’t leave the glow starter on take it off to give the glow start and glow plug a break and then try again.

2. If you suspect your glow plug or glow start is not working then you can check this by unscrewing the glow plug (if you have one of our glow start sets you can use the hexagonal wrench to do this) and attaching it to your charged glow start to see if the wire on the opposite end of the glow plug lights up. If it does then you know there both fine but if it doesn’t then either the glow plug, glow starter or charger is not working. If you know someone with a nitro model then it will be easy for you to eliminate each part until you find out which part is the problem part.


For basic maintenance information please see our “what you need to check before use” section on our web site. If you are serious about the hobby though and want to keep your car well maintained you should maintain the following items:

General Cleanliness – A clean car is a happy car! Not only that, but you will be able to spot problems easier on a clean car than on a dirty car, and also while cleaning it, you can give the car and body a quick look to see if anything is wrong. Use a large natural-hair bristle brush (from a hardware or paint store) to remove dust from the chassis and inside of the body. Use some denatured alcohol or motor spray to clean off tyre and asphalt marks from the outside of the body.

Differentials – These let the outside wheels in a turn spin faster than the inside wheels, so the car can maintain the proper path when turning.

For cars using gear differentials, you should check the areas around the diff shafts for grease leaks every 20 to 25 runs. If you see a leak, you need to take apart the diff and put more grease in it, and reassemble it carefully.

If you run a car with ball differentials, you should check the diffs for grittiness every 5 runs or so. To do this, put the car on a stand so the wheels can rotate freely. Hold the spur gear and slowly turn a wheel. Try to feel if the action is smooth or ‘gritty’. If it feels gritty or the wheel is difficult to turn, you need to rebuild that diff. Now check the other diff using the same technique. You can use diff rings and thrust washers twice – just flip them over to a smooth side. If you don’t have a smooth side on the rings or washers, you need to buy new ones. We don’t recommend using diff balls and thrust balls through more than one rebuild – you should replace these each time you rebuild a ball differential. Carbide diff balls will last longer under the same circumstances as regular diff balls.

Shocks – Shock absorbers soak up bumps in the track and let the tyres maintain constant contact with the racing surface; they also let the tyres dip into depressions in the track. If you are a ‘backyard basher’ or casual hobbyist who doesn’t race, you should give your shocks a look over before each time you run the car. If you see any leaks, you need to rebuild your shocks. When rebuilding shocks, you should always use brand new o-rings. Never re-use old o-rings!

Racers should check their shocks before and after each run. Any leaks mean it’s time for a rebuild. Shocks on a racing R/C car should be rebuilt or given a good look every ten or fifteen runs. Be sure you write down what shock oil you are using in the car! Either write it on the shock cap in a fine-point permanent marker or use a Setup Sheet . When rebuilding shocks, you should always use brand new o-rings. Never re-use old o-rings!

Drive Shafts – These transfer the power from the engine to the wheels so are under a lot of stress. Whether you race indoors or outdoors, you should check the shafts before the day’s racing begins for any bends or wear on the ends. Replace any that need it or consider upgrading to our CVD ones under upgrades.

Drive Cups – These connect the drive shafts to the wheels and diffs. They are held on by grub screws and making sure these screws are tight is very important. Use strong threadlock on any loose ones. If a drive cup screw comes loose and you do not notice it could damage the differential and other components.

Bushings – Used on most rotating parts on sport or budget kits, bushings are better than direct contact between the parts, but not as good as ball bearings. Bushings don’t need any maintenance to speak of, just keep them clean and grease them when they are first installed.

Ball Bearings – Used on most rotating parts on pro-level kits, bearings provide a way to eliminate almost all of the resistance that bushings have and serve to make the car quicker overall. For kits with the standard shielded bearings (metal shields on the side), just brush them off every now and then. You may want to put a very light dab of oil and let it soak into the bearing, but for the most part just brushing the dirt off the bearing is fine.

Gear Mesh – The relationship between the primary drive gear (pinion or clutchbell) and the secondary drive gear (spur gear). A tight gear mesh (the spur cannot ‘wiggle’ when installed) has too much friction and will cause the motor or engine to work too hard and could melt the spur gear from the friction. A loose gear mesh (the spur can move significantly) will probably cause the pinion gear to strip the spur gear, ruining the spur gear.

To set a proper gear mesh on electric cars, use a small piece of normal notebook or copier paper and put it in between the pinion and spur, and tighten the motor onto the motor mount. Remove the paper, and that is how much gear mesh you should have. For Nitro cars, you can get away with a little bit looser gear mesh than on electric cars because the gear teeth are much larger. Use the same technique described above, but fold the paper once before you put it in between the gears.

One-Way Diffs – Many racers do not lubricate the one-way differentials as often as they should. Every few runs, you should take the one-way diff out and remove the gear shafts to inspect the bearing. If there is no hint of grease on the bearings you should use a very small amount of the blue-capped grease that comes with the one-way diff (the amount of grease that would end up on a toothpick or pin if you dipped it in the grease) and re-lubricate the one-way bearings inside the main diff body. This will help prevent a major cause of one-way diff failures. Crashing and no lubricant are the main reasons why the one-way bearings in the one-way diff break.


There’s lots of small jobs that you can do on a nitro radio controlled car to make it run better and last longer. Following some of these easy to follow tips and see great improvements.

1. The antenna tube is quite brittle when new. If you take the antenna tube and boil it in a pan of water for a few minutes it will become soft and flexible. It will be easier to fit and if you flip your model it will not break!

2. Glueing your antenna tube to the mounting will ensure it does not come loose and fly off when racing.

3. Take a zip tie and thread it through the fuel tank lid to aid opening the tank lid whilst using.

4. Use silicone bathroom sealant to seal your receiver box and any gaps where leads are exposed. Apply a small amount of sealant to the bottom of your receiver box lid before screwing the casing back down. Also apply some to the underside of the chassis top plate where the servo and switch leads enter the receiver box lid.

5. Tape your 4 cell receiver pack batteries up with some insulation tape. Wrapping a small amount of tape around your battery pack will ensure they do not vibrate loose and cause you to loose control.

6. When doing a jump you can actually control the car in the air. If it starts to nose dive give a quick blast on the throttle to level it out and if the car starts to climb like it is going to land on it’s back wheels applying the brake will correct it.

7. If your aerial is to long and a lot is coming out of the top of the tube do NOT cut it. Instead use a small amount of fuel tubing over the aerial tube to hold the aerial neatly and securely to the outside of the tube.

8. Cut tiny holes into your body shell next to the body mount holes and feed a short piece of fishing wire through the hole. Knot the end going through the shell so it can not come out and then tie the other end to your body clips. No more lost body clips!

9. If the seal on your fuel tank is broken or you want it closed more securely attach an elastic band to the rear of the tank, feed it under the tank and up the front and attach it to the handle on the lid. As the band is stretched it will be constantly pulling the lid closed.

10. The steering links come attached to the bottom of the outer fixings. By removing the screw and attaching from the top should give a more stable car over the rough.

11. If you are getting grip role and your model flips when you go round a corner snip the outside tread off the tire to reduce the grip and make it slide instead.

12. If you are using an off road model (such as the Condor or Conquistador) on long grass screw down the threaded collar on the shock body to increase the ride height.

13. Make sure there are no leaks around the engine and manifold which would decrease engine power and performance. Use high-temperature gasket or silicon sealants (such as Hylomar from Halfords) around areas such as the carburetor to the engine, the exhaust manifold to the exhaust port of the engine, and the back plate or pull-start mechanism against the engine block.


The nitro engines we sell are two-stroke, air-cooled (water-cooled marine) engines. They feature a true “ABC” (Aluminum, Brass, Chrome) construction. The chrome sleeve has a slight taper so the aluminum piston fits tighter towards the top of the sleeve compared to the bottom. When the engine reaches proper operating temperature its perfect running tolerances will then be achieved. The piston will feel tighter when the engine is cold.

Fuel enters the engine through the carburetor where it is mixed with air. The fuel/air mixture is then drawn into the crankcase. The crankshaft has a rotating valve, which opens and closes the crankcase to let fuel into it. On the pistons down stroke, the crankcase becomes pressurized, and fuel is blown into the combustion chamber through intake ports cut into the sleeve. On the upstroke, the fuel is compressed and ignited. When first trying to start your engine, the electrically heated glow plug causes the fuel to ignite. Once the engine is running the fuel is ignited by rapid compression in the combustion chamber. The exhaust is then released through a third port in the sleeve.

The oil that is contained in the fuel mixture lubricates the surfaces of the piston and the sleeve. The oil in the fuel also helps to cool the engine while running. Some of the oil is burned when in the combustion process which is what creates the blue smoke trail from the car.

The air to fuel mixture is critically important. A mixture that is too “rich” means that there is too much fuel, a mixture that is too “lean” means that there is not enough fuel for the given amount of air. When the mixture is too rich, performance will be sluggish. There is also a high potential to foul the glow plug when running the car too rich. When the mixture is too lean, there is not enough oil to lubricate and cool the engine parts. Running too lean will almost certainly damage internal engine parts as well as foul the glow plug.


Install 4 “AA” batteries in the receiver pack on the car. Next install 8 “AA” batteries in the transmitter. When installing the batteries be careful not to push the metal conector tabs on the controller down causing a bad contact. If you do this just pull them back up with a screw driver.

Turn on the radio system and check that all servos are working correctly. Check all the linkages to make sure they are not binding. Always remember, the transmitter is the first to be tuned on and the last to be turned off. Never turn off the radio when the engine is running. To stall the engine you can either run it out of gas or cover the exhaust hole. The switch on the car only turns off the electronics in the car, not the engine.

Always make sure the batteries in both your car and your radio are strong or fully charged. Attempting to run your car with weak batteries will make the car not respond to users controls. It could even completely become uncontrollable and become a “runaway car” and severely damage the car.

Check the wires from your battery and your antenna wire every few runs. These wires could become damaged and result in loss of control.

Before starting the engine, always check the range of the transmitter before running the car. Short range can be the result of a broken antenna wire or weak batteries.


The Rev switches:
These reverse the direction the servo moves when you pull the trigger or turn the wheel. If when you turn the wheel right the car turns left then flip the St Rev switch to correct this. If the brake comes on when you pull the trigger flip the Th Rev switch to correct this.

The Trims:
Your controller will have two dials or sliders. These are used to align the controls. If for example when you are driving the car pulls to one side you can use the steering trim to line it up so it drives straight. You can use the throttle trim if when you turn the radio on the servo opens the throttle or applies the brake to put it back to neutral.


The first thing you should check is to make sure that when you pull full throttle the carburetor is fully opening. If you take the air filter off and pull the trigger all the way back it should open completely. You should always keep the engine within its intended operating temperature. Going above these could and most likely will cause damage. As you lean the engine out, it will run faster and faster till you hit a point where it will overheat. When this has happened it will start to stutter, hesitate, or even stall. The engine will over heat very quickly when the mixture has been set too lean. Check the engine often when leaning it out to make sure its not overheating.

The simplest way to test for over heating is to put a drop of water or spite on top of the engine head. If it boils away instantly shut the engine down and let it cool off. If it takes 5-7 seconds for the water to evaporate away, then the engine is running at a good temperature.

When you have the mixture set correctly you will hear the engine running smoothly and have a strong-sounding high pitch when you let it wind out. Running the engine a little “rich” is always a lot better then running it to “lean”.

Once again: Lean = less fuel
Rich = more fuel

The high-speed mixture will affect the way engine runs at mid and high R.P.M.s. This is the main needle that you will adjust the most. Once you get you engine running good, this will be the only needle that you should have to mess with.

Run the car on a smooth flat surface with enough room to let the model get up to top speed. Keep track of the speed as you slowly (1/8 of a turn at a time) lean the engine. You can lean it as long as you continue to have thick blue smoke coming out of the pipe. If the engine gets up to top speed and looses power most likely you have “leaned” it too much. You want the high-speed mixture to be lean enough to get good power and still keep the engine cool. Use a temperature gun or the water test to check the temperature of your engine. Remember, you want the engine to run around 270′ or water to sit on the head for around 5-7 seconds.

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