FCR tuning – Carburetor synchronization work – 2022-11-02

FCR tuning – Carburetor synchronization work – 2022-11-02

I had time, so I did some synchronization work on the FCR carburetor.
If you touch the idling stop screw,
There are differences between carburetors in groups 1, 2, and 3 and carburetors in groups 4, 5, and 6.
I'm very concerned about this because I'm focusing on low throttle opening when tuning.
It's not that much of a difference.
Finish by making minor adjustments by lowering or raising the idling.
I wish I could improve my judgment accuracy to the point where I can judge just by looking at the return of the sound and response.
You won't learn these things unless you increase the number of times you work and work consciously.

FCR current tuning

[Current tuning]
SJ-48
AS-1.25 minutes return
PS-1.05 minutes return
JN-90FXM#3
MJ-130
Acceleration pump diaphragm KLX250
Acceleration pump discharge timing 1.6mm
AS Uotani SP2-Ignition [1]

There's also the temperature, but I felt it was a little heavy at low throttle openings.
I left it lean for about 5 minutes.
I haven't touched anything else since the other day.
Rather, the other day I was touching the screw based on cold startability,
Today will be a test run. It accelerates comfortably without any problems.
Looking at the air-fuel ratio meter, it seems that the area in charge of the clip position is rich.
The clip position is selected with emphasis on feel, so
For the time being, we will be running on rich. Actually, I think that [2] is better for the number of clip stages.
When I changed from [2] to [3] rich, the feeling of acceleration increased.
Currently it is set to [3].
I think rich is better in most cases.
Even if I say rich, it's about 12.5.
It's a different story if it happens for a moment, but if the air-fuel ratio is below 10.5 at Constance, it's a strong rich condition.
Tuning needs to be reviewed.

For FCR beginners – synchronization and idling are dangerous without adjustment

There are some motorcycles that idle too high or have trouble slowing down the engine.
It's dangerous. Too high an idle is the same as opening the throttle that much. There is no problem if you just start or drive at low speed.
When you brake suddenly or slow down, your speed may not slow down.
If the idle is too high, lower it.
A slow engine speed can cause an accident.
Even when cruising at a high speed, the throttle opening is not large.
It is dangerous if there is a large time lag for the engine speed to drop.
This is the case when one cylinder has a high rotational speed.
The engine speed will slow down in synchronization with the cylinder that has high RPM.
In my case, I'm clearly concerned about synchronization too much.
If the engine speed slows down, you will need to resynchronize the carburetor.
Or, if you use a low throttle opening, the rotation will slow down better.
I'm concerned about engine speed drop.
It's easy to go down if you're rich around the slow port area.
If there is little difference between the slow port and idle port, the rotation will drop.
Of course, this assumes that the carburetors are synchronized to some extent.
A motorcycle with a good engine rotation rate will make a pleasant sound when you twist the throttle.
There is no problem as long as the idling is not extremely high and the synchronization is properly maintained.
On the other hand, if the engine slows down or the idling is unnecessarily high,
There are deficiencies regarding the two points above.
You have no choice but to request a motorcycle shop or do the maintenance yourself.

FCR tuning – Carburetor synchronization work – 2022-11-02【summary】

The wiring on the throttle grip came undone and the throttle wouldn't move unless I squeezed it hard. I fixed it right away, but my hand got a little tired because the throttle became heavier as the throttle was idling.
When I find some free time for a change of pace, I like to play around with the FCR and take test runs in the mountains behind the bike.
Very fun.
In addition to test runs and tuning, cleaning is also necessary.
It's getting cold soon.
I want to ride a lot of motorcycles beforehand.
Please be careful about synchronization of the carburetor.
Please enjoy your FCR life!
See you again!

Photo gallery of CBX1000’s FCR synchronization work

Since we are doing the same work in the same place, there is no substitute.
Personally, I feel like my work speed is getting faster every time.
Tools and preparation arrangements have been improved, and since the tank can be attached and detached, it is possible to replenish less fuel to prevent accidents.
I try to make something different every time. Lately, I've been wondering if there's a way to carry a fan with me.