FCR-MJ main jet purchase 36 pieces

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FCR-MJ main jet purchase 36 pieces

Currently, MJ's stock was limited to 102-128, so I purchased additional items.
6th place: 130,132,135,138,140,142.
I purchased it as a POSH set.
I bought a set of 6.
I bought 6 pieces in a 6 piece set.
I will be purchasing a total of 36 items, but I feel very uncomfortable.
I want to buy only the number I need, but I won't know which one I need until I try exchanging it.
Also, although I wrote this as needed, there are usually only 4 pieces in stock at the shop.
You will be in a situation where you will need to order each time. As a set when you buy each number one
When you buy one, the price is about 25% different.
If you buy it from POSH, it is not a genuine KEIHIN product, but it is a product that requires precision.
Although it is a third-party product, I purchased it on the assumption that it would be unlikely for a domestic manufacturer to have poor accuracy. Also, it comes with a case, which makes it feel like a good deal.
By the way, the case is separated into six rooms.
I was a little impressed that all six MJ numbers were in the same position.
I have inspected the item and there is no mistake in the number listed.


It has Tenchi Muyo on it, but the package is opened horizontally.
Fragile items are not packaged, so there is no problem. It's just a little bit of attention from the shop.
I ordered Wako's Fuel One to get free shipping, but the Tenchi Muyo sticker was attached so that the bottom of Wako's Fuel One was on the ground.

MJ main jet inspection and labeling

When I bought it, I didn't want to buy an aftermarket product.
When I opened it, I was happy to see that the case was sturdy.
The leftover case looks like a pill case and could be used for something.
I was reminded of the importance of labeling in a previous blog post, so I did it this time. Collecting MJ is not my hobby, but I'm kind of happy when I have more MJ on hand. Previously, I was slowly purchasing MJ one by one. Recently, I noticed that I couldn't really feel the difference in MJ unless I shook it extremely hard, so I bought it all at once. This time I'm currently using MJ-125, but I'm thinking of raising it to about MJ-135 and then lowering it one step at a time.

FCR-For beginners-MJ selection

This is a story when you don't have an air-fuel ratio meter or dyno jet.
If the main jet is too thin, the piston will melt. Probably true. I don't know how lean it needs to be to make it melt because I've never melted it before. However, I have melted the piston by lowering the plug count, so it is true that the piston will melt.
By the way, I used MJ102 in my CBX, but it didn't go bad, probably because I didn't drive at full throttle often. I think something around 120 would be good for CBX.
I'm thinking about it now. Of course, there must be individual differences. How to change the air fuel ratio from MJ110 to MJ120
I feel like it gets about 0.8 richer when I turn it on.
It's not a proportional change.
Some motorcycles change by 1.2, while others change by 0.5. If you want to make it richer, just increase the value by about 10 and lean it little by little. To make it leaner, just make the first or second layer leaner. Specifically, how to choose MJ, if you want to see full throttle, it is difficult to select without an air-fuel ratio meter or dyno jet. However, if you look at the throttle opening from 1/2 to 3/4, the acceleration and feel will change to the extent that you can experience it. Unless the MJ is so lean that it will damage the engine, you can select the MJ based on the feel of the throttle opening from 1/2 to 3/4. Of course, this is a measure to be taken when measurement is difficult, such as when there is no air-fuel ratio meter.
It is quite difficult to drive at full throttle for 3 seconds on public roads.
If you want to proceed with the tuning by feeling, rather than the extension when the throttle is fully opened,
Perhaps it would be better to look at the feeling of acceleration from 1/2 to full throttle and the growth at partial.

The JN jet needle is designed to pierce MJ. The thickness of the tip of the JN jet needle is 1.2 pi. There is a difference in the combination of MJ and JN due to the subtle taper.
When the throttle is fully open, MJ will be the only tuning. If you are in an environment where you can measure and set at full throttle, you can enjoy tuning while checking the balance between MJ and JN.

MJ’s influence range

FCR-MJ renge
FCR-MJ renge
The manual says that it only affects up to 1/2 of the throttle opening, but I feel like it affects about 1/4 of the throttle opening. Also, although the statement says that the effect on throttle opening 1/2 is minimal, it feels like it has a larger effect than the graph shows. It will be easier to judge if you change the MJ count value by about 10. For example, the change from 115 to 125 can be easily seen. You can't tell just by changing the number one, such as from 115 to 118. If you change the value by 10 and don't notice any change, MJ's number may be way off.

FCR-MJ main jet purchase 36 pieces【summary】

Looking at the stock of jets, we have the ones with high asset value on hand.
This is enough for you to use it even if you get a second motorcycle.
For personal use like me, there are some jets that I have never used. Or there may be jets that are used only once and never used again.
However, if you just have it on hand and can try out various things, the range of tunings will expand, so I think that's a good thing.
I would be happy if there was a CBX owner in my neighborhood who was tuning up FCR.
Unfortunately, he is not there.

I will still be using a carburetor called FCR in 2022. It seems that no new carburetor motorcycles have been designed after 2000. It appears that sales have been going on since 2000.
There are only 4 jets in each face-to-face shop.
It doesn't seem like it sells often.
This time I ordered via mail order. FCR carburetors are sold in large numbers.
For the time being, there will be no need for parts.
I'm grateful to KEIHIN in Japan for being able to order a jet today and get it tomorrow as I set it up.
Please enjoy your FCR life.
See you again!
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