FCR Tuning – Symptoms of too rich and too lean – Air-fuel ratio meter also recommended

FCR Tuning – Symptoms of too rich and too lean – Air-fuel ratio meter also recommended

Words you will definitely see when tuning your FCR.
[rich]
[lean]
They seem clear, but are very vague.
For example, there are expressions such as
[little rich] and
[too rich] for rich.
If you mix in current expressions such as [currently rich] when you are not sure of the appropriateness, it becomes even more difficult to understand.
I often use ambiguous expressions myself.
Some people may say that the same tuning is appropriate, while others may evaluate it as too rich or too lean. In short, it is very vague.
You need to translate the degree to which others express rich or lean in your own way and use it as a reference.
In this blog post, I will write about the symptoms of too lean and too rich.
If the symptoms are similar, you should be able to feed them back into your own FCR tuning.
Okay, let's go.

Symptoms of engine running lean enough to break down

I have never had an engine blow up because the FCR was tuned too lean.
I heard this directly from a trusted senior mechanic.
When an engine breaks down, it breaks down in an instant.
He said that being too lean with the main jet is particularly the problem.
As I will explain later, if it's too lean, you lose a sense of power and can't accelerate properly.
At high speeds with the throttle fully open, where the main jet is in charge,
you can reach quite high speeds. So the theory is that if you run the engine at high RPMs while it's too lean,
the engine will break down.
Extreme engine braking from high speed driving on a circuit etc. while it's particularly lean is dangerous.

How to determine if you are too rich or too lean

This description is based on the assumption that even if the current tuning is not the best, you can still ride without stress to a certain extent.
If you change the jet needle clip stage drastically and test drive the bike, you will notice the symptoms of "too rich" and "too lean".
This should be a very useful experience as you proceed with tuning.
First, let's explain what "too rich" means.
It causes misfires, or rather the engine stutters and you can't drive properly. Even if you twist the throttle, the engine won't turn. When you experience this condition, you will probably say,
"This is too rich..."
Next are the symptoms of "too lean".
The engine will still turn, so the change may be difficult to notice.
When you test drive the bike within the range covered by the clip stage, you should be going at the same speed as if you were riding normally.
The throttle will become lighter, or rather the motorcycle itself will feel lighter.
It will feel empty and lacking in power.
The leaner it is, the less power it feels.
In the case of my CBX1000, due to the number of clip stages, I was not able to increase the clip stage until the problem occurred, so I was not able to judge the symptoms of too lean, but excessive engine braking causes backfire. You should understand the feeling that the more lean you make it, the less power you feel. If you only lose a little power, the acceleration will feel lighter, so depending on how you open the throttle, you may like it.
Checking the clip stages for [too rich] and [too lean] and being aware of the symptoms will help you tune at each throttle opening.
If you feel that there is not enough acceleration at the very least when the throttle is fully open, it is either too lean or the motorcycle has been properly tuned at its limit.
When the throttle is low or fully closed, symptoms such as lean and rich are difficult to notice while riding.
It is better to judge by whether there is a sense of power when starting, or by the engine's starting ability and idling atmosphere. In the case of my CBX1000, when the throttle is low, I feel like it runs well when the ratio is around 12.9 when the throttle is fully closed,
around 12.5 when the throttle is 1/16th open,
and around 12.5 when the throttle is 1/2th open.
There are many complex factors involved, such as carb synchronization and idling speed.
Some people have told me that it's better to run lean when idling.
In the case of the CBX1000, an air-fuel ratio of around 14.0 seems to affect the starting ability of the engine and the throttle return when racing.
Currently, I have it tuned as above when the throttle is low.

For FCR beginners – First try different clip stages

It is very effective to change the clip number drastically while test riding to check the symptoms of [rich] and [lean]. If you find a clip number you like in the process, you can proceed with tuning based on that clip number. Backfires and black smoke rarely occur depending on how the engine brake is applied or the timing of the acceleration pump.
Beginners often have absolutely no idea. You probably don't know which is correct. You don't know if the symptoms apply to your motorcycle. What is written on the web or in magazines is correct for the person who wrote it, but it is unclear whether it applies to the reader's motorcycle.
It should be kept as a reference. At least, checking the condition of your motorcycle with the clip number makes it easier to judge your own motorcycle. It is best to touch the air screw, etc. You should be able to judge whether it is in good condition or not without touching it. Once you have confirmed the symptoms of lean and rich, set the clip number to the appropriate number.
After that, adjust the air screw and fine-tune the tuning to make it run smoothly.

FCR Tuning – Symptoms of too rich and too lean – Air-fuel ratio meter also recommended【summary】

[Rich] and [lean] are expressions for which direction to swing the jet from the current state.
I remember reading in old magazines that tuning has a certain flavor,
but generally speaking, good tuning will result in a similar jet tuning no matter who does it.
Humans are creatures that can transmit information.
There are many things in the world that can serve as reference, such as past tuning methods.
Give yourself feedback on such verbal expressions.
If you have a standard in your mind for the symptoms of rich or lean, it is a shortcut when tuning.
I feel like trying various things based on my own experience was a detour.
I think that taking the detour was a good thing because it increased my knowledge.
However, it's better to do things quickly.
Make sure you can absorb knowledge from the web and from your predecessors.
The accuracy of your tuning will improve dramatically.
If you are having trouble with [rich] or [lean], try changing the number of clip stages on the jet needle to get a feel for it. It will definitely help you with tuning.
See you again!

CBX1000 Photo Gallery

This blog post focused on [rich] and [lean] and I will post a photo of an air-fuel ratio meter - A/F gauge from a previous post.