tuning of FCR – If the small jet needle is F taper, you cannot choose the cut-up. Round up comparison

FCR-jet needle CBX
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tuning of FCR – If the small jet needle is F taper, you cannot choose the cut-up. Round up comparison

First of all, please take a look below. FCR's jet needle constant inventory table is small and large.
You can check it with.


オートバイカスタムパーツの総合メーカー アクティブ
As far as you can see, the [E] taper is the basic one. I can't help but feel like the large is basically telling you not to use anything other than the E taper. Small has more overall numbers than large, but [E] taper still has more options. With F-taper, you cannot choose the cut-up unless you order it in units of 20 pieces. Just because the taper of the jet needle installed by default was [F] If you proceed with the tuning in F, you may get stuck at the end of the cut. I am not a carburetor tuning specialist, so I basically focus only on the CBX. I'll write a story. If you are using a large body, this story may not specifically apply to you. Thank you for your understanding.
FCR-jet needle Stock list
FCR-jet needle Stock list
The image is a screenshot of the active site. I have excerpted this information because it is publicly available.

Large body jet needle

Large body [OCETM]
Small body [90ETM]
Use the prefixes [OC] and [90] to determine whether it is for large body or small body.
Especially for large bodies, there are only two options: [E] taper and [F] taper.
There is no such thing, so riders who want to enjoy tuning by changing the taper angle should be careful.
In addition, even if it is difficult to select JN due to the characteristics of the motorcycle, SJ or MJ may be more suitable than JN.
If you are not conscious of it, you may get stuck if you absolutely have to change the cut-up or taper angle.
Please be careful as this is possible.

Comparison with jet needles of the same thickness, etc.

I would like to apologize in advance, but please understand that the results may be incorrect or the measurement method may be sloppy, resulting in theoretically incorrect results.

The straight diameter changes by 0.01mm at No. 1.
This is about small jet needles.
Rounding up is not required unless special order is made.
[E] taper [T] and [Z]
[F] Taper is only [T]
[G] Taper is [M] and [T]
In the case of [F] taper, this seems to mean that if the number of clip stages exceeds the upper limit, the taper should be changed.
If you need to try using [F] Taper to increase the number of clip stages above 1, use [G] Taper.
That's all I can think of.

The straight diameter is set to 2.755mm.
When tuning the caliper to 2.7mm and comparing the thickness at the same position
You can see that the F taper is about 2 to 3 steps higher in terms of the number of clip steps.
If you want to change only the rounded-up part
For F taper
By changing to G taper, the number of clip stages can be moved up from 2 to 3 stages.
In short, if you want to increase the number of clip stages above 1 with an F taper, use a G taper.
I feel like I'm receiving a silent message when I look at the list of Jet Needle's standard stock.

Caliper is 2.6mm
Let's compare.
The straight diameter of 90FTM is 2.715mm.
There was a difference of about 1 step in the number of clip steps.
It looks like there will be a difference of about 1 clip stage by lowering the straight diameter to the 4th position,
If you try to change the straight diameter and get the same cut
So I'm thinking that a difference of 8th place is necessary.
It's not that simple since it's about the angle.
I feel that it is impossible to match the number of clip stages with the straight diameter.
This comparison method is also sloppy and has low accuracy, so I don't know if it's reliable.
This should be a helpful reference when choosing a jet needle while looking at the numbers on the tuning table.

90FTS (2.765mm)
90FTM (2.715mm)
Compare with
Caliper is 2.6mm
The difference is about 1 step in the number of clip steps.
If you try to make a difference in the number of clip steps based on the straight diameter, the 4th one will be about 1 step.
If you compare up to this point, you can see how much the number of clip stages changes.

In terms of main jet numbers,

When changing from 128 to 125, the straight diameter of the jet needle is 3rd,
I think it will be about 90FTM → 90FTQ. Because of the angle and location,
It is unclear how strongly they influence each other, but they interact with each other.
Please use this as a rough reference in terms of numerical values.
90FTR on the left, 90ETR on the right.
Due to the difference in taper angle, there is a difference of about 3 stages in the number of clip stages.
Left 90FTM, right 90ETR
With the fourth change in taper angle and straight diameter
There is a difference of about 1 clip stage.
Left 90FTM, right 90FTS
By changing the straight diameter number 5
There is a difference of about 1 in the number of clip stages.

For FCR beginners – How to choose a JN jet needle

If you want perfection, you have no choice but to look for it steadily.
If you're fine with the 80% type, any size is fine as long as it's not too far off.
In that case, leave it as the default.
I think that SJ and MJ alone will make up for it to some extent.
You won't be able to find the perfect count right away, so please repeat the steps below.

① Start from the default shipping state
②Start from reverting AS1.0 and PS to 1.0
③Open the AS little by little and repeat the test run.
④ Every time I test drive, if the start becomes sluggish, open the PS and make adjustments.
⑤If AS or PS exceeds the manual specified value of 3.0 and 3.30 minutes, change the SJ size to a larger size.
The opposite is possible, but the manual should assume that SJ is to be shaken from small to large.
After repeating this, change the number of clip stages 7 times to your favorite size,
Adjusted AS and PS.
Once you have decided on the number of clip stages, find your favorite straight diameter while doing AB tests.
Finally, change MJ from the larger size to the smaller size.
The process is to repeat the above steps 3 steps forward and 2 steps back to refine the tunings.
I think the MJ looks good even when running at 1/4 to 3/4 even at other than the highest speed.
In the end, you should see how it feels when it's fully opened.
There aren't many places where I can try it out, but I'm trying my best to test it out every day while looking for opportunities.
I have no choice but to do it. If you are in an environment where you can use Dynojet etc., it is easy to check the full throttle.
If I see something wrong with the air-fuel ratio meter, I use the air-fuel ratio meter's readings as a reference to change the jets that are affecting the throttle opening. Depending on how you open the throttle, it should be around 12.5 when accelerating and around 11.0 when partially.
My CBX is currently using 90FTQ#1.

tuning of FCR – If the small jet needle is F taper, you cannot choose the cut-up. Round up comparison【summary】

Rules for the number of clip stages that I have roughly decided for myself.
The change in taper is the third largest change in the number of clip stages.
The change in straight diameter is equivalent to 1 step at 4th position.

I'm currently thinking of trying out changes beyond the upper limit of the number of clip stages with the [F] Taper.
[F] Taper does not have a standard jet needle tuning for changing the cut-up, so
The situation is that we have to wait about 1.5 months for a special order of 20 pieces.
FCR rarely becomes unable to run, so depending on the SJ size, MJ size, screw etc.
It seems like you can make adjustments to make ends meet, but I'm starting to think that the number of clip stages is an area where such adjustments don't work. The number of clip stages is 1 stage and there is a feeling of power, but when you lower it to 5 stages,
The bumps were so bad that I no longer felt like riding.
It's important to look at the numbers, but the jet needle is a tuning that completely changes the overall feeling. Even if you custom-order and get the best jet needle for yourself, if you try to change it,
You will have to make two special orders for the front and back.
We ended up having to custom order 60 pieces of 3 types.
I find myself wishing it was a 20-cylinder motorcycle.
BITO had a jet needle with a count of 90FXM, so I ordered it.
I think it would be possible to balance the books by changing SJ and MJ between numbers 2 and 6.
SJ can be adjusted with a screw, and MJ has a wide range of influence, so this is not the case.
Even if the tuning is not perfect, what I was concerned about,
I hope this will be a hint to help you understand.
I learned many things after ordering 12 E-taper jet needles.
There is a high possibility that it will not be used in the future.
Still, there were a lot of things I noticed, so I'm okay with the result.
Tuition fees were high
I think it's because I paid for it that I thought about it and researched it myself.
Well then, I hope you all have a good FCR life!
See you again!

In the next post, I will make a light comparison between 90FTM and 90FXM.
Comparison of FCR-jet needle cut-up. Let's take a look at the thickness of the small standard 90FXM and 90FTM.
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