Nitro engine Tuning

The nitro engine of your RC car is like a human heart. In order for it to run effectively you have to take care of it, tune it, and don't beat it up too much with a rough track or potato chips.
Now different engines, like different hearts - lovesick ones or cold ones - behave differently. A nitro engine, for example, requires a different maintenance technique than electric. It takes time to learn how to really tune your engine, however. There's a certain feel and sound to your car when it's tuned properly, which you'll learn once you've perfected the craft.
This can be confusing for even the most weathered RC enthusiast, so to help you out, we've compiled a list of tips and tricks to keep your nitro engine running smooth like butter.

Your Nitro Engine: The Basics

 

Clearing the engine:
There are four fairly simple steps to take when clearing your nitro engine of debris, dirt and oil residue.

• First off, raise the idle to ¼ turn (the idle screw and not the low-end needle). This will help stop the engine from stalling.
• Wait until the engine temperature reaches about 145-150 degrees.
• Richen (turn to the left) the top end screw by a full turn.
• Hold the carburetter wide open, continue richening (turning left) the top end until the engine comes close to stalling (you should be able to hear it cutting out). This should flush out all the nasty dirt, oil and grime that gets stuck in the carburetter and engine.

Out-of-the-Box Tuning:

Starting with the engine manufacturers' (if included) base-line settings for your RC's mixture needles is your best bet. If there is no base-line provided by the manufacturer, then you have to adjust the needles until you can get the engine started.
However, the normal starting point (widely used) is at 1 turn open (counterclockwise) on the low-speed needle while adjusting the high-speed needle to between around 2 or 3. Sometimes the results will vary, but after you get the engine started you can make any corrections. It's not until you're finished that this initial start-up process will break in the car until any kind of race-tuning is necessary.
So next you adjust the needles. There's a chicken before egg and vice versa debate in the RC world about which sequence is the right one for adjusting mixture needles, but most Nascar-style professionals start with the high-speed needle for regular tuning.
When you're breaking in your nitro engine however, the engine will probably idle for a while, so you should adjust the low-speed setting to run a bit rich first (loading up about every 30 seconds).
Your engine may require an occasional little flick of the throttle to clear out any unused fuel that has built up in the engine. Once your engine is broken in, you can adjust the high-speed needles.
Alright, to get a good first run you want to find a long flat surface ideally. So you should set the car down, and accelerate really smoothly, no quick starts, until the engine heats up. If your high-speed needles are around the right spot, you should be able to get almost to top speed once you've been running it for a couple of minutes.
You'll want to run the engine through a few tanks of gas to break it in, without ever taking it to full speeds.

Tuning for the Race Track

Racing tuning is intended to make the racer go as fast as possible in as little time as possible.
So here are some tips to get you started. First, you'll probably want to clear the engine (see the instructions above), and then start tuning the bottom end. Once you've started to tune the bottom end, you should listen to it idle. If the idle slows and you stall the engine, lean (turn right) the bottom end needle. If the idle speeds up a lot, you'll want to richen (turn to the left) the bottom end needle.
Now, you should set the engine to idle for around a minute before the engine starts to stall. Once the idle stays around the same for a minute, lower the idle screw setting as far as you can until the engine stalls. Now you should open up the idle screw setting by 1/8th of a turn.
Now, your engine should idle pretty consistently for at least 45 seconds.
Next, you want to tune the top end. So first you should open it full throttle for about 2 seconds, then go back to idling. Next it's time to get your ears adjusted to what a good engine sounds like. Listen to the engine and lean (turn right) the top-end needle until the sound is crisp and clear. Next, you should open the carburetter to full throttle for about three seconds, close it for the same amount of time, and then open it for three seconds again. Kind of like a lather, rinse and repeat.
Your engine should sound great and clean for those two revs. If there's any hesitation when you rev, it's probably too lean and you'll need to richen (turn left) the top-end needle a bit. (.rc-airplane-world)