The popularity was split between the 70s and 80s, and currently the Z series has a larger market share, but I'll write about the differences. The main difference between the CB-F and Z series engines is the number of valves. The Z series has two valves, while the CB-F series has four. Putting aside the things that are not immediately accessible or visible, such as a strong engine or powerful output, it all comes down to this one point.

Tuning the FCR requires adjustments based on the weight of air and fuel. As the temperature drops, the density of the air increases, making the air heavier. In response, it is necessary to either increase the weight (amount) of the fuel or reduce the amount of air.

How Far Should Carburetor Synchronization Be Done?When performing synchronization using a vacuum gauge, there are graduations to consider.Is it acceptable for the reading to be off by one graduation?Does even the width of the black line on the gauge count as an error?There are many questions. Recently, I was able to hear the answer from the legend, Mr. Bito.

I will write about starting the engine of a motorcycle with a carburetor in the early winter mornings. Logically speaking, the Honda Cub, which was commonly used for newspaper delivery in the past, starts the engine easily with the choke and kick start, even on cold winter mornings. Now, regarding motorcycles equipped with FCR carburetors, they don’t have a choke, but you can use the accelerator pump as a substitute. By twisting the throttle about three times and then waiting for about 10 seconds before turning on the starter motor, the engine starts up normally.

Comparison of brakes from the past and present: Even when comparing a CBX1000 equipped with a recently manufactured complete brake system to a CBX1000 that is using well-maintained, 40-year-old brakes, the performance difference is significant.

When you purchase an FCR, it comes with a red Velocity Stack. It’s a 30mm red plastic Velocity Stack. The Velocity Stack of the FCR can be considered the 'exhaust' on the intake side. It is an essential part for smoothing the airflow.

When you change the straight diameter of the jet needle, you may need to change the clip position as well, or else the performance can become quite poor. It’s difficult to specify exactly how many steps you should change the straight diameter before adjusting the clip position, but it seems reasonable to think that changing the straight diameter by about five steps would correspond to a change of approximately one clip position.

For those of you who are contemplating whether or not to purchase a vintage motorcycle, I think this is an interesting topic. My conclusion is that as long as the engine is running, it can be managed. If you aim to faithfully reproduce the looks and performance of the motorcycle when it was new, maintaining it might be impossible, but if the goal is simply to ensure it runs smoothly, the challenges become much easier to overcome.

Where do you all mount your air-fuel ratio gauges? The air-fuel ratio gauge needs to be carefully monitored during high-speed runs, especially on straight stretches of road where it’s crucial to check the readings. On my CBX1000, I’ve removed the stock voltmeter and positioned the air-fuel ratio gauge right in the center of the meter cluster for easy visibility.

It’s important to make adjustments to the FCR as soon as you notice something off. I’m considering adjusting the throttle low opening screw range and the air-fuel ratio at wide open throttle to be about 1.0 richer. I changed the Slow Jets (SJ) and Main Jets (MJ). This year, I decided not to change the SJ.

In FCR tuning, the initial values for the screws are typically set to an air screw (AS) of 1.00 and a pilot screw (PS) of 1.00, as stated in the tuning manual. This content suggests that there might be an additional level of power available even after achieving what seems like the best tuning.

I attended the 11th JB-POWER Meeting on October 29, 2023 (Sunday). I will focus mainly on the atmosphere of the venue. Photos are compiled at the bottom, separate from the text. My personal reflections will be kept modest, and I will primarily guide you through the venue's ambiance.

The FCR air screw and pilot screw are parts that can be adjusted continuously. In contrast, the slow jet and main jet needle can only be adjusted with specific sizes. The air screw is easily accessible once you remove the filter or velocity stack, making it straightforward to observe changes.

Having an air-fuel ratio gauge (A/F meter) is convenient for FCR tuning. Even without a gauge, you can achieve precise settings through real-world riding once you get accustomed to it. You can adjust mid to high-speed settings based solely on your feel. In fact, it might be better not to get too caught up in the numbers. However, it can be challenging to determine whether the throttle opening at low speeds is functioning well or poorly.

This is regarding the scope presented on page 8 of the FCR tuning manual. This page indicates the impact range of tuning, but it raises the question of whether the X-axis refers to the throttle opening or the valve opening. This is something I posted about recently; the throttle opening and valve opening of the FCR are not directly proportional.

I'm describing the effects of changing the main jet, focusing on how it influences throttle positions other than full throttle. After changing the main jet, I went for a test run. My assessment is centered around the changes observed from around half-throttle to three-quarters throttle rather than focusing solely on the full throttle range.

I’m framing this as fine-tuning rather than tuning in the strictest sense. The tuning of the FCR is the result of repeated A/B testing. It’s a process of searching for jets that improve performance, and then finding even better jets from those improvements.

Even when the throttle is opened to 1/2 on an FCR, the throttle valve on the FCR does not open to 1/2. This is not specifically mentioned in the FCR tuning manual. Knowing this might change your perspective on the operation of the FCR throttle. At 1/2 throttle opening, the throttle valve is typically open only about 1/4.

When installing a quick turn throttle, one feature that is not present in a standard throttle housing is the throttle stop screw function. Although it might sound elaborate, it is simply a screw hole that has been cut. It is a bolt used to adjust the minimum return position of the throttle.

For adjusting the throttle area, there's no problem at all in thinking that you can easily do it yourself without needing to rely on a professional. For such tasks, you can usually find methods by searching online. If you still have trouble, you can consult a local motorcycle enthusiast, and you’ll likely find a solution.