FCR-PS Isn’t it too rich? How to decide between pilot screw and slow jet

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FCR-PS Isn’t it too rich? How to decide between pilot screw and slow jet

I've been worried about something ever since I started using FCR. This is how to return the pilot screw.
The other day, when I was synchronizing, I noticed something, so I'll write it down.
There are few people who specifically write about how to decide on slow jets and pilot screws.
I'm writing what I noticed, so my description may be different from the actual one.
Please understand if I write something wrong.
It is assumed that an air-fuel ratio meter is installed.

I've tried it before, but does it idle with the pilot screw fully closed?
The engine will idle.
I was idling with slow jet 52.
If the slow jet is large, there will be so much fuel that the pilot screw will not work.
It may still be idling even with the pilot screw fully closed.
It's like adjusting the idling only with AS.

When FCR's low rotation is,
There is an idle port and a slow port.
The idling port is the hole that carries most of the fuel when idling.
A slow port is a hole that starts working when you start opening the throttle a little.
I don't know specifically what throttle opening is effective.
I think it's probably around 1/4 throttle opening.

Until now, I had been casually touching the pilot screw and air screw.
It's whether the starting performance is good or bad when you engage the clutch.
When you look at the air-fuel ratio meter at the idling port, it should read about 13.0.
There is no problem with idling or engine starting when fully closed.
Of course, it is necessary that the pilot screw is within a certain range.
Just changing the slow jet will increase fuel consumption. I think this is because fuel is also supplied from the slow port.
Even if you enlarge the slow jet and close the idle port when fully closed,
I think it can idle because fuel is supplied from the slow port.
The basic return time for the pilot screw is 1.00 minutes, but this is just the basics.
Starting from the largest slow jet, reduce the size and move the pilot screws the same on all cylinders.
You should choose a slow jet number that allows you to adjust the air-fuel ratio within the appropriate range.
The straight diameter of the jet needle and the number of clip stages also have an effect.
It is better to keep it fixed until you find a slow jet that falls within the appropriate range of the pilot screw.
On the other hand, if you fix the pilot screw at about 1.00 minutes and change from a small slow jet that cannot idle to a large slow jet, you will find a pilot screw that has the appropriate pilot screw range. .
We have confirmed that the air-fuel ratio is between 12 and 17 when fully closed and idling possible.
Idling is possible when the air-fuel ratio is 12 or less.
If the amount is too rich, by opening the AS, the amount of air that is not working due to the pilot screw is increased to ensure a proper air-fuel ratio.
So, this is my way of deciding on the slow jet and pilot screw.

FCR-For Beginners-How to find the right slow jet

If you don't have any types of jets on hand, adjust PS or AS,
If you adjust the position so that it is easy to start when clutch engages from idling, it is OK.
When I was focusing on feeling, no matter how many times I tried it, the air-fuel ratio at stable idling was 12.9 no matter how many seasons I tried it.
The desired result is to have good idling conditions.
We have no choice but to do what we can't do to the best of our ability.

The above method requires an air-fuel ratio meter and several SJ numbers.
In fact, the biggest hurdle is installing the air-fuel ratio meter.
You can do it by feel even if you don't have an air-fuel ratio meter,
It's hard to understand. I know how the air-fuel ratio changes by looking at the air-fuel ratio meter, so
Even without an air-fuel ratio meter, you can find a slow jet with the pilot screw working.
can. Until I noticed that the pilot screw was still working even though the air-fuel ratio meter was installed.
It was not possible to determine what happened.
To do the above, just change the slow jet size and touch the pilot screw.
Anyone can do it if they know the logic.
At least with CBX, this is the way to go.

Idle port and slow port

The idle port is the area in charge of the pilot screw.
The slow port is the area in charge of the air screw and slow jet.
The slow port is located on the funnel side across the throttle valve.
When the throttle opens wide, it starts to work more strongly.

please refer.
↓Past articles will open↓
About FCR-PS. Idle port, slow port and air-fuel ratio at idling

スローポート= slow port
アイドルポート= idle port
エンジン側= engine side

FCR-PS Isn’t it too rich? How to decide between pilot screw and slow jet【summary】

If you are tuning the slow jet from thin to rich, you can tune it with the pilot screw working properly.
If the slow jet is too rich and you are tuning at a fixed PS of 1.00 minutes,
Idling is being adjusted using only the air screw.
I don't notice that it's too rich when the pilot screw is fully closed.If you can drive well even when the pilot screw is not working, there is no need to worry too much.
It is worth trying at least a motorcycle with a fixed pilot screw return of 1.0 minutes.
If you feel that the PS is too weak, try closing the PS completely and see if you can idle the car. You may feel that the slow jet is too large.
See you again!
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