You’re noticing that your 4 stroke RC engine is producing too much smoke. And it also runs quite sluggish. You need to tune it properly to get the best results.
So the question is how to tune a 4 stroke engine?
You have a high-speed needle and a low-speed needle. Rotating counterclockwise leans the engine, which gives it less fuel and more air. And rotating clockwise riches the engine, which means it gets less air and more fuel. It should be balanced between lean and rich. Lean gives better performance.
Well, now you know the basics. But there are still more explanations left as to how to do it properly. Because it’s a matter of delicate balance.
And that’s why we prepared an article explaining them! Let’s get into it!
How to Tune Your 4 Stroke RC Engine?
Firstly you need to start your engine. And then you can advance on tuning it. There are a few steps you need to follow.
There are a few different regions where you need to tune. Firstly you need to tune your high-speed needle. And once it’s adjusted you need to tune your low-speed needle.
And you’re going to tune your idle setting at the very end. And most times if you have tuned your high and low speed properly, then you won’t need to tune your idle speed.
But if your idle speed is very high from the get-go, then there will be no harm done if you are tuning it alongside the others.
So let’s see how to tune a nitro RC plane engine.
1. Start the Engine
The first and foremost step is to just start the engine. And then you can get started with your tuning work.
So just put adequate amounts of fuel in your fuel tank. Then you can use an electric starter to start your engine.
Or you can use your hand to turn the propeller. You should use quite a bit of force so that it spins a bit fast. That’ll make the engine take some fuel in. And then using the throttle you can start your engine.
If from the very start, there is a lot of smoke coming from your engine. Don’t be worried because non-tuned engines tend to produce more smoke.
2. Tuning the High-Speed Needle
Start by taking a flathead screwdriver and leaning on the high-speed needle. You need to lean it in small increments. 1/16th of a turn will suffice for each step.
As you lean you’ll see that your propeller rpm will increase. Make sure to fasten the propeller tightly so that it doesn’t fling out and cause an accident.
Keep leaning it and see how the rpm changes. You’ll see that the rpm will keep increasing up to a point and then when you lean further the rpm will drop. You’ll hear and sense the decrease.
When it passes the full throttle then richen it a bit. Keep going back and forth until you find that perfect spot where the rpm isn’t dropping.
Now that your high-speed needle is tuned, your low-speed needle will be rich.
3. Tuning the Low-Speed Needle
Tuning the low-speed needle is much faster than the high speed needle. But it also requires more care and carefulness to do so. As the low-speed needle is more sensitive than the high speed needle.
Firstly run your 4-stroke glow engine at full throttle for a while and then bring it to idle. Wait for nearly 10-12 seconds and let it idle, and then nail the throttle.
If the engine acceleration doesn’t feel smooth then it’s rich. You need to lean it but turn the needle 1/16th of a turn.
Repeat this until you have fairly good acceleration. Keep in mind that you should have moderate smoke coming from the exhaust. And no liquid fuel should be coming through the exhaust.
Tune your engine, if the engine revs up too much then it’s too rich. And if it barely revs up then it’s too lean. Find the sweet spot by going back and forth with small turns.
And now your engine is tuned! That’s the way to properly bring out your RC engine’s best performance. Alongside that you can also learn to set timing on 4 stroke engine.
Why Is Tuning the Engine So Important?
Tuning is basically adjusting the air and fuel mixture. For getting the most out of your engine you carefully adjust the mixture percentage in your carburetor.
There are two main controls for adjusting this. There is a high-speed needle as well as a low-speed needle. Turning these two clockwise and anticlockwise will control if your engine will learn lean or rich in fuel.
The function of the high-speed and the low-speed needle is adjusting the rich and lean settings for different speeds. For high-speed scenarios, the high-speed needle is used. And for low-speed and idle settings, we use the low-speed needle.
Turning the needles clockwise means you’re running it lean. And turning counterclockwise means you’re running it rich.
One thing you should always follow is that you need to run your engine a bit rich. Because running your engine lean all the time will overheat the engine. And the engine will get damaged beyond repair.
Rc plane engine tuning is quite easy. And it doesn’t require a lot of parts. Get yourself a flathead and you’re good to go!
Some people who are extra fancy, do use a tachometer. This measures the rpm of the blade and shows when is the perfect time to stop tuning.
This is the list of a few available tachometers out there. If you feel fancy you can get one for yourself.
But most people, who are used to tuning their engines, can do it just as perfectly just using their ears. So it’s better to develop that sense rather than relying on more devices.
Result of Bad or Incorrect Tuning
Running your engine rich keeps your engine cooler. Also, it will receive more lubricant and that will increase the life of your engine.
But it will make your engine lag behind. And it’ll not reach its full potential.
But if you run your engine too lean, it’ll get worn out too fast. Due to increased temperature.
So it’s about balancing and finding that sweet spot. Leaning will increase your engine’s performance but lean it to a certain point where the engine is still getting some slack.
Tune according to performance and that’ll give you the best setting automatically.
FAQs
Q: Is Overheating Bad For Brushless DC Motors?
Ans: Yes, overheating is bad for brushless DC motors. Brushless DC motors are basically magnets. And they run with the principle of induction. But heating decreases the magnetic properties of a magnet. And overheating can make a magnet lose its magnetism permanently.
Q: Does the Engine Run Leaner In Cold Weather?
Ans: Yes, it does. In cold weather or winter, the air is cold as well as the density of air is increased. So the engines get dense air and the cooling gets better while lean. This makes the engine more efficient so a leaner mixture is recommended.
Q: Are Brushless DC Motors More Efficient Than Brushed DC Motors?
Ans: Yes, it is. Brushless DC motors are the fastest and most efficient of all motors. As brushed DC motors need to touch the carbon brush, it will inherently cause friction. That causes heat and wear. But as brushless DC motors don’t have anything touching, they run cooler and better.
Wrapping Up
Now you should know how to tune a 4 stroke RC engine. You need to remember that balance is the key to a good-performing engine.
Until next time, take care!
- SCX24 Motor Upgrade Guide 2024 [Step By Step] - January 1, 2024
- RC Helicopter Shaking – 4 Reasons And Solutions! - September 24, 2023
- 1/10 vs 1/16 Scale RC – Which One Should You Purchase? - September 24, 2023