Have you ever wondered about the orientation of plugs?
For those who thought that there is such a thing as direction, or for those who thought that it is common sense, the experiment by "IKABEL" introduced in this issue of [MOTO HACK] is quite an interesting result!
The spark plug has the function of ignition, which is essential for combustion in an engine, and if you look closely, you can see that the tip of the spark plug has a "U" shape.
It is clear from its structure that the degree of combustion depends on which way it faces in the engine. There is indeed an ideal plug orientation that can use the entire combustion chamber evenly.
A typical plug has an electrode extending to the tip of the plug. This creates an obstruction and affects the condition of the combustion chamber.
Even those who know such things as knowledge, however, are not likely to have experimented with changing the plug orientation and visually checking the condition of the cylinder head. There are no instructions in the motorcycle manufacturer's manuals that specify the direction of the plugs, and it is not likely that power is reduced because the plugs are not facing the right way in everyday use. Therefore, there are few opportunities to check the plugs.
However, Mr. Ikabel questioned the orientation of the plugs on his beloved Grom and the structure of the combustion chamber and actually tested various orientations. It was a great test that clearly showed that the influence of plug orientation cannot be easily ignored by looking at the condition of the carbon in the combustion chamber. The results of this experiment are interesting for riders who are challenging themselves in races and tune-ups, and new discoveries are sure to emerge from the challenging spirit of actually trying out what you already know!
Orientation of the spark plug outer electrode for good combustion efficiency
From Ikabel's maintenance diary, May 31, 2022.
First of all, please note that this is an original experiment, and the findings and opinions are in the process of being tested, so please keep them for reference only. Please practice at your own risk. I cannot be held responsible for any wrong opinions.
It is known that the direction and height of the spark plug outer electrode with the highest combustion efficiency exists, but in the case of JC92E, there is a bank next to the spark plug hole in the head dome. I think that this bank is also there to increase the efficiency of the explosion (blast), and the best direction of the spark plug outer electrode should exist based on this. I wonder which direction of the outer electrode gives the best explosion (blast).
I will not talk about the height this time.
It has been a year since I bought my JC92, and I have had the opportunity to remove the cylinder head several times, at which time I tried several different orientations of the spark plug outer electrode.
I verified that the:
- Outer electrode on EX side (top 45 degrees)
- Outer electrode is placed on the bank side (top 180 degrees, piston side)
Incidentally, the best explosion (blast) assumption is assumed to be:
- The blast spread evenly throughout the dome.
- The vector (here we refer to the magnitude and direction of the force) caused by the blast should be directed toward the piston side a lot.
We have not yet tried all angles, but our current knowledge and opinion are that the best case is when the outer electrode is placed on the bank side (top 180 degrees, piston side). The riding experience is also different in that the engine pulse is the most energetic and torque.
Let's continue to play around with various trials and errors.
1. Outer electrode placed at EX side top 45 degrees, red arrow
Generally, it is believed that for automobiles, it may have been a good reverse to point the outer electrode to the EX side.
However, there is no carbon on the other side of the bank, to the right of the outer electrode.
In other words, uneven combustion is occurring.
When I drove the motorcycle, there was nothing wrong with the engine. It was a hoot.
But there is such uneven combustion.
2. When the outer electrode is placed at 45 degrees on the EX side
There are areas far from the plug where the carbon is not extensively attached.
That must mean that the blast is not getting around.
There is a difference in sooting of the valve compared to when the outer electrode is placed on the bank side top 180 degrees and on the piston side. I guess that means there is a tendency for incomplete combustion on the IN side.
I was able to run it just fine.
So, it is not a good idea to point the outer electrode to the EX side.
When the outer electrode is placed on the bank side top 180 degrees and on the piston side
Compared to the case where the outer electrode is placed on the EX side (1), there is clearly less uneven combustion.
The amount of carbon deposits farther away from the dome is still higher than when the outer electrode is placed at 45 degrees on the EX side (2). But because of the distance from the plug, the amount of carbon deposition tends to be less than around the plug.
Ideally, the entire dome should be evenly coated with carbon.
Currently, these are the only two patterns we have tried.
My current opinion is that it would be better to place the outer electrode on the bank side top 180 degrees and on the piston side.
The actual driving experience was that the engine beat was the most energetic and had the most torque. The sound of the engine was louder than when it was placed at 45 degrees on the EX side.
If I have a chance, I will try the top 0 degrees and 90 degrees.
Procedure for good placement of outer electrode orientation
Now, we will explain the procedure for better placement of the orientation of the outer electrode when installing the spark plug.
First, use a magic marker to mark the position of the outer electrode so that you can grasp the position of the outer electrode as shown by the red arrow in the photo.
Also, apply a thin layer of thread compound to the threads.
This will not only prevent thread burn-in but also improve thermal conductivity.
If you mark them, you can figure out the location of the outer electrode like this.
The torque for tightening the spark plug is 16 Nm.
Use a copper washer (10 mm) to align the outer electrode based on this.
Since it is a copper washer, it provides better thermal conductivity and helps to exhaust heat from the plug.
This is what I mean by a bank.
Thank you for your valuable ideas, "Ikabel" who introduced the "Orientation of Spark Plug Outer Electrode for Better Combustion Efficiency".
*The articles on MOTO HACK are composed and reprinted from user contributions. The effects and methods described are at the discretion of the user, and Webike is not responsible for any problems that may occur.
