Comparison of idle port and slow port of FCR carburetor

HONDA CBX-FCR-Air fuel ratio at idle FCR
This article can be read in about 8 minutes.

Comparison of idle port and slow port of FCR carburetor

I hadn't been aware of it until now, but this is a story that makes me feel like I understand the difference in air-fuel ratio between the idle port and the slow port.
There was an incident where I was able to see the difference between fully closing the throttle and opening it slightly to about 1/16, so
I will write it down.
First of all, I would like to disclaim that I am a programmer by trade and not a motorcycle shop staff member, so please understand that I may contain incorrect information or expressions.
It may be hard to see in the photo, but there are two holes.
The hole on the engine side is the idle port, and the hole on the outside of the engine is the slow port.
The slow port is almost invisible from the engine side when the throttle is fully closed.
What I will write about this time is, as I wrote earlier, when the throttle is fully closed, the air-fuel ratio will exceed 14-15.
There was a phenomenon that when opening at an extremely low opening of about 1/16, it would drop to around 12.
I will write about it. Details are also uploaded in the video, so please check that as well.
Please confirm.
FCR Cross section
FCR Cross section *The text in red in the image is translated below.
スローポート = slow port
アイドルポート = idle port
エンジン側 = Engine side

The explanation in the cross-sectional diagram may be incorrect, but please take a look at it for reference only.
I don't know the details of how it works. This type of climate control is not installed on CRS carburetors, so this is an improvement specific to later carburetors.
tuning the pilot screw changes the amount of mixture discharged from the idle port.

What is the difference between FCR idle port and slow port?

At the idle port, turn the PS pilot screw to adjust the amount of fuel.
When the throttle valve opens, the slow port becomes visible, so when it becomes visible, the discharge switches to the slow port, or the idle port and slow port overlap, causing a change in the air-fuel ratio.
I felt that this is what it means to control engine startability and idling with PS.
I realized that this is what the engineer who specializes in Z said when he said that the idling air-fuel ratio was 14th. I happened to find it this time, but I didn't notice it because it was usually around 12.5 even when idling, and there was little difference between the idle port and slow port.
It is unclear to me whether the air-fuel ratio at the idle port is around 14 or around 12.5.
We will make adjustments while determining whether it will affect starting performance or ease of riding.
It also seems to have an effect on how the tachometer returns when racing FCR,
I'll try to care.

Check operation on YouTube

It may be difficult to understand, but most of the time the throttle is compared with the throttle not twisted and the throttle fully closed. Although it is written as 1/16, it may actually be less than 1/8, so please understand that.

For FCR Beginners – Pilot Screwdriver

It's a blind spot, or something I haven't noticed until now, but it's hard to see the changes in the pilot screw unless you turn it while the engine is running, so you can't set it.
If you are new to FCR, you probably don't have this tool, but if you don't have it, you will be unable to adjust the PS.
Also, it seems that there is no driver of a size that can be properly adjusted for CBX,
I use a sharpened screwdriver.
Up until now, I had neglected the PS pilot screw, so
I was impressed when I was able to make adjustments while the engine was running.
From the perspective of enjoying FCR tunings, it is an essential tool, so if you don't have it, please consider purchasing it.

Please refer to past articles.
pilot screw adjusting tool processing

Comparison of idle port and slow port of FCR carburetor【summary】

I had researched various things beforehand about the difference this time, so I didn't know the cause or the mysterious symptoms.
She noticed right away. I'm planning on doing it. I think my thoughts are probably correct,
Also, the longer you touch the FCR, the more
You may notice something again. However, as a veteran mechanic said,
I think you touched on the meaning of the idling air-fuel ratio being around 14.
As for what is the appropriate level for CBX when fully closed idling,
I haven't looked into it yet, so I'll start looking into it little by little.
I hope you all have a fun FCR life!
See you again!
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