FCR tuning-JN-22/06/02

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FCR tuning-JN-22/06/02

This is a story about changing JN and changing clips after tuning the carburetor.
The other day, I touched the oil surface, removed the SJ, and touched it a lot, so
Just to be sure, I once checked the synchronization of the 6 cylinders of FCR.
Honestly, it was at a level where I didn't have to touch it much.
In the past, I tried to perform thorough synchronization, but slight deviations may occur depending on the tension of the stop screw or accelerator wire, so considering the time and cost of perfect synchronization, I decided to reduce the precision of synchronization a little. I try to use my time for other things.
Having two stop screws and two accelerator wires, which reduce synchronization accuracy, is not very advantageous. If there are disadvantages, there are also advantages, but I have not found them yet.

tuning scenery

I pack my tools in a backpack and go deep into the mountains to work, where there are few private homes.

FCR tunings

SJ-55
JN-90FTR#1
MJ-125
AS-1.35 minutes
PS-1.15 minutes
→
SJ-55
JN-90FTS#2
MJ-125
AS-1.20 minutes back
PS-1.15 minutes
→
SJ-55
JN-90FTS#3
MJ-125
AS-1.25 minutes back
PS-1. Go back 15 minutes
→
SJ-55
JN-90FTS#4
MJ-125
AS-1.30 minutes
PS-1.15 minutes
→
SJ-55
JN-90FTS#5
MJ-125
AS-1.25 minutes
PS-1.15 minutes
→
SJ-55
JN-90FTR#2
MJ-125
AS-1.40 minute
PS-1.15 minutes

This is how I approach it.
The feeling may be different from last time as we have increased the fuel level.
I did a test run by tuning the AS several times until it looked good.

What happened when you changed the jet needle?

JN has a higher fuel concentration, but I think it's better to choose based on the feeling you get while driving.
I feel like the weight of the throttle is different between the 90FTS and 90FTR, and the lightness when running is also different. I get the same feeling with clips.
Until last year, I liked the light feel of the 90FTS, but now I like the powerful feel of the 90FTR. Of course, I feel that changing the size of MJ or SJ will also change the feeling.

What should I do with the FCR screw?

An air-fuel ratio meter is required.
I'm thinking a lot about how to touch the screw.
It says that the AS and pilot screws can be set separately for each cylinder, and the manual says that they should be set separately for each cylinder, but for the CBX, I currently set them all in the same way. The reason is that you cannot tell the difference when tuning the screw in each cylinder.
PS is basically fixed at 1.0 minutes or 1.15 minutes.
AS is measured by clutch engagement and power feel when the throttle is opened very low, and how it feels when the throttle is opened suddenly. Touching the PS changes the feeling of power when the clutch engages, so I open and tighten the PS when I only want to touch the clutch engage. When I looked at the intake manifolds, it seemed like the flow rate was high only in intake manifolds 1 and 6, or there wasn't much fuel adhering to the intake manifolds, so it might be a good idea to open PS 1 and 6 a little more and see what happens. If the number of screw returns for each cylinder is extremely different, it means the engine is malfunctioning or something is broken or clogged.

For FCR beginners

The number of clip stages for JN (jet needle) is counted from the top. Count from the 1st row to the 7th row. I have not considered taper and undercut.
*It is difficult to have it on hand because it is expensive and there are too many types.  
I am replacing JN by looking only at the straight diameter. There are different types of JN: large and small.
When tuning up on the street or at a roadside station, you will be in trouble if you lose the clip, so be sure to carry a spare with you.
It is better to have at least 2 sets of JN including the installed ones.
It is easy to compare the good and the bad.
Once you have an air/fuel ratio meter installed, it will be easier to decide which direction to buy jets.

FCR tuning-JN-22/06/02【summary】

How much should I change the clip if I change the straight diameter of JN by one?
I confirmed that.
I tried changing the JN clip and number of stages, but nothing was the best.
Even though the straight diameter of the clip has changed, the appropriate position may not have changed. 90FTS may be out of the range of tunings in the first place.
Maybe it just doesn't feel right to me.
I try to touch it as soon as I feel like it.
Let's move on to the topic of purchasing JN thread count.
I feel like SJ can be fooled to some extent by using screws.
MJ is easy to replace.
And since it's cheap, it's easy to have a lot of counts in advance.
However, JN is expensive and there are so many types including tapers that it is difficult to have a lot of spares. JN that the manufacturer does not have regularly must be purchased in a minimum lot of 20.
By the way, the price is 715 yen (including) per book when purchased from NAPS. Since CBX has 6 cylinders, you will need 4,290 yen to buy one. It's a little pricey to buy a spare for some reason.
Still, when I bought the second set of JN and replaced it, it changed so much! I remember being impressed. After repeating this process, I ended up with about 10 sets, which cost 42,900 yen for 60 pieces in total.
It's a strange number that seems like it's not a big deal in terms of money.
This time, the content has become a thin post.
I will play FCR for my own experience points.
I hope you have a good FCR life!
See you again!
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