Installing an FCR on a CBX1000! 10 points to consider when starting serious tuning

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Installing an FCR on a CBX1000! 10 points to consider when starting serious tuning

I received an email asking me to explain in detail about my last blog post. This time, I will write about what is necessary to start tuning FCR in earnest.
This is not for DIY beginners. However, even beginners can clear it with motivation.
The perspective is for those who want to start tuning FCR in earnest from now on.
And I will write mainly about CBX1000.
I only own CBX1000 motorcycles, so I can't write about anything other than CBX1000.
I will write about CBX1000, not about other motorcycles, such as synchronization, air-fuel ratio, main jet size, and acceleration pump adjustment.
At least I touch FCR quite frequently in its current state.
Whether it is right or wrong, I will write it as one result.
I will not explain each one in detail, so if there are any points you are interested in, please look it up separately. As of 2022, information is easily available on the Internet.

Installing an FCR on a CBX1000! 10 points to consider when starting serious tuning

The CBX1000 is a 6-cylinder air-cooled engine.
Many people probably think that tuning the FCR is difficult even before they try.
If you don't know what to do, please read this.
I've listed some points that you may be concerned about in bullet points.
① What do I need to synchronize?
② What size is the main jet?
③ Should I use an air-fuel ratio meter?
④ Should I adjust the air screw for each cylinder?
⑤ Should I change the ignition timing?
⑥ Does it make a difference with or without an air filter?
⑦ How do I keep track of the tuning data?
⑧ The response is poor, what should I do?
⑨ Is an acceleration pump unnecessary?
⑩ About the wear on the FCR body

Here are 10 points that I'm concerned about. There are many other points that I'm concerned about.
I'll write down 10 points that I'm concerned about.

①What do you need to synchronize?

I use two 4-gang vacuum gauges to make a 6-gang setup.
Calibration is required every time.
If you don't trust the calibration, you can use a carb synchrometer to calibrate with one meter.
The CBX1000 has vacuum nipples on numbers 3 and 6, and depending on the year of the FCR, only number 6. My FCR is an older model, so only numbers 3 and 6 had vacuum nipples installed, so I added vacuum nipples to numbers 1, 2, 4, and 5.
You can also easily synchronize by clamping a wire to the throttle valve so that the wire falls at the same time when the throttle is opened.
This may be more accurate than using a multi-vacuum gauge that does not have a needle calibration.

↓Opens previous article↓
FCR synchronization and 6-series vacuum gauge

②What size is the main jet?

I'm concerned about seizing when driving with the throttle wide open.
Between 115 and 138. In this range, there is no seizing.
There was no seizing even when driving at 105. The CBX1000 is in an area where tuning is not possible when driving with the throttle wide open on public roads.

③Should I install an air-fuel ratio meter?

If you are going to do serious tuning, it is a good idea to install an air-fuel ratio meter.
The meter should be installed in a place with as good visibility as possible.
By installing an air-fuel ratio meter, even amateurs can see the specific air-fuel ratio, which even experts cannot understand. Welding is required for the muffler. Please consult with the manufacturer before purchasing the muffler.
There is a high possibility that additional processing can be done before shipping.
When tuning using an air-fuel ratio meter, you tend to check the partial numbers,
but if you aim for 12.5 partials, the tuning tends to lack a sense of acceleration.
As you become more familiar with tuning, it is better to tune by feeling the acceleration during a test run.
Depending on the effectiveness of the acceleration pump, the air-fuel ratio may become lean for just a moment, indicating an air-fuel ratio that seems to be accelerating, such as pointing to around 12 to 13.

④Should the air screw be adjusted for each cylinder?

The FCR tuning manual says that in the case of a multi-cylinder engine, air screw adjustment should be done for each cylinder, but in the case of the CBX1000, after the RPMs of each cylinder have increased, it is better to return the air screw to the adjustment position it was in before the RPMs increased by one degree before adjusting the next cylinder.
I use a digital tachometer to see the point at which the RPMs increase. When the RPMs increase at one point, the point at which the RPMs increase for the other cylinders becomes unclear and I cannot determine it.
It may differ depending on the individual engine or the type of motorcycle, but I take an average and adjust each cylinder to be returned the same. I set it to 5 minutes back from the average. The tuning manual says 1/4 turn. A rich tuning will cause fewer problems than a lean tuning.

⑤Should I change the ignition timing?

I have installed AS Wotani SP2 on my CBX1000.
I tried ignition timing [0], [1], and [2], and it didn't break even when I was driving at full throttle.
[9] is a retarded ignition timing, but for me it didn't feel very good when I drove.
The feeling is that the more advanced the ignition timing, the more powerful it feels, and it feels like it's leaner overall. I'm currently tuning it to [1]. I've also reviewed the tuning itself.
Looking at the ignition curve of AS Wotani SP2, it doesn't seem to have any effect when changing the ignition timing at low throttle openings. It says what kind of engine it's suitable for, but you can choose the ignition timing that gives you a sense of power. For the CBX1000, there is no ignition map for AS Wotani SP2 TPS. Ignition is controlled only by the RPM.

⑥Is there any difference with or without an air filter?

I use a ram air filter. I haven't felt any difference with or without a ram air filter. There may be some difference, but perhaps because I have a preconceived notion that there is almost no difference, I haven't felt any big difference with the shape of the funnel, the presence or absence of a filter, or the application of filter oil. Somehow, I feel that a straight carburetor gives a sense of power, but I try to install an air filter on my CBX1000 whenever possible.

⑦How do you keep track of your tuning data?

Tuning is a process that involves comparing before and after. It's an AB test.
And you need to keep a record of all your work.
In my case, I keep a record of my work in a Google spreadsheet.
I don't record the temperature, humidity, or altitude, but I always keep a record of at least the changes to the FCR and the date. If you're serious about tuning your FCR, it's essential to keep a record of your work.

⑧The response is poor, what should I do?

There are various things you can do, such as lowering the idle or synchronizing.
By tuning and synchronizing the idle port and slow port with attention,
you may be able to improve engine speed drop.

⑨Is an accelerator pump necessary?

If you ask whether it is necessary or not, it is.
When you start tuning, it may be a good idea to try delaying the discharge timing or turning it off by clipping the push rod to see what changes it makes.
If you have an air-fuel ratio meter, you may be able to see the moment the acceleration pump is working numerically.
You may also think that changing the acceleration pump diaphragm will allow you to adjust the time when the discharge ends rather than the total discharge amount. Acceleration pumps cannot be precisely tuned, so it is better to think of it as a countermeasure for when the throttle is opened suddenly. If you use a large quick throttle, the effectiveness of the acceleration pump will change significantly. It will help you understand better if you remove the funnel and check how the acceleration pump discharges fuel when the engine is stopped.
Also, the way fuel is sucked in is different when the engine is started and when it is stopped. If the discharge timing is too early, the fuel will hit the throttle valve directly.
Even if you adjust the width of the plate to the position described in the tuning manual, the acceleration pump discharge timing may not be set as intended.
Please check visually.
I set the discharge timing to about 3/8 of the throttle opening.

↓Opens previous article↓
FCR Tuning – Easy way to turn off the acceleration pump


The FCR reaches the end of its life when the bearing part of the throttle valve wears down and ruts form in the body.
To address this, there are big rollers and SEP bearing guides.
It is not necessary to install them up front, but we recommend installing the SEP bearing guide as soon as possible. The big rollers are a stopgap measure when the FCR reaches the end of its life.
The weaknesses of the FCR are the rough adjustment of the acceleration pump and the wear on the body caused by the throttle valve moving up and down.
The TMR eliminates these weaknesses.

Installing an FCR on a CBX1000! 10 points to consider when starting serious tuning【summary】

This is a blog post with endless content.

I'm not a professional in this field, so there may be many other things to check.

-How many jets should I get?

-What will be the fuel economy?

-What about the compression gauge?

-What about the oil flow rate?

-What color are the plugs?

-Should I get new plugs?

Just by writing a rough outline, many questions will come up. By the way, I'll write my own answer:

-I'm running at a fuel economy of about 10 to 12 km/l. The fuel economy varies greatly depending on how I drive, and if I'm driving at a fuel-efficient pace, it's about 14 km/l.

-Even if the compression is low, there's nothing I can do about it right away, so I assume that it's in perfect condition.

-Even if the oil flow rate is low, there's nothing I can do about it, so I assume that it's in perfect condition.

-I don't see the color of the plugs as a tuning issue. I check them occasionally to see how the engine is doing.

-I replace the plugs with new ones when I put too much fuel into the acceleration pump and they get dirty. I change them regularly.

I assume that the minimum level of maintenance and overhaul has been done.

If I were to start talking about the condition of the machine, I would have to start by completely disassembling the engine.

The above is text-based, but I have also included some photos at the bottom that may be relevant.
In the next post or so I will explain my own method of tuning the main jet.
Well then! See you again!

CBX1000 FCR tuning related photos

I will post photos of tools and disassembly. If you are motivated, you can buy the tools and jets and do it. By the way, my main job is a programmer.
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