Improving fuel efficiency with FCR carburetors

Improving fuel efficiency with FCR carburetors

I occasionally see discussions about the fuel economy of FCRs, some positive and some negative.
If I were to write about it on social media, it would lead to arguments with others, so I'll write about it on my blog.
The answer lies within each person.
I'll write my own opinion in a column format.
I'm only talking about the CBX1000, but I pride myself on being better at removing and attaching the FCR than the average person.
The fuel economy of my CBX1000's FCR is roughly 12km/L.
I don't know if this is good or bad. That's because I don't compare it frequently with other CBX1000s.
If you pay attention to your riding, you can get better fuel economy.
When it came to fuel economy, it was sometimes as bad as 7km/L.
When it gets to this point, there's definitely something wrong with the FCR.
I couldn't clearly find the cause, but I think it was because the slow jet was strangely green. I disassembled the FCR and cleaned it. It improved when I reset it.
When I test drove it with my current sense, it felt terrible.
I have seen posts on social media saying that the fuel economy is about 15km/l.
It may be that for a four-cylinder engine with the best tuning.
Another factor is the riding style of the rider.
If there are no problems with the FCR and the tuning is good, fuel economy will not be extremely poor.
I think that good fuel economy is close to the best tuning.

Should you look for fuel efficiency in an FCR?

Because the FCR is a racing carburetor, fuel economy should not be the first priority when tuning.
The first priority should be to deliver the air-fuel mixture in good condition.
If fuel economy improves as a result, that's great.
To tune to improve fuel economy, turn off the acceleration pump, set the air-fuel ratio to about 13.5 with the throttle opening at 1/8 or more, and ride carefully, and you will improve fuel economy.
This tuning will make you feel that the acceleration is somehow lacking.
If you touch the slow jet, for example, you will not be able to start, so do not touch low throttle openings.
As mentioned above, if fuel economy is extremely poor, there is a high possibility that there is a problem with the FCR tuning itself.

Driving methods that improve fuel efficiency

This is my way of riding that improves fuel efficiency.
I will write this assuming I am touring.
The most fuel-efficient way to ride is simply to be conscious of not letting the oil temperature rise.
You don't need to worry about RPM or rich orlean tuning.
Driving in a way that doesn't let the engine oil temperature rise will mean not consuming fuel.
My CBX1000 has a sensor attached to the oil pan.
Keep it up to about 80 degrees.
If you drive carefully, you may be able to drive with an oil temperature below 80 degrees.
There are also seasonal factors.
You can get better fuel efficiency by being conscious of the oil temperature rather than trying to not raise the engine RPM.
Not raising the oil temperature is related to not raising the RPM.
It should improve fuel efficiency considerably.
However, it is an unimaginably unenjoyable way to ride.
There is stress involved in riding.
If you let your guard down and accelerate, the oil temperature will rise immediately.

Does tuning improve fuel economy?

Tuning will probably improve fuel economy.
If you tune the engine so that the air-fuel ratio is around 13 to 13.5 with partial throttle at 1/4, 1/2, and 3/4 throttle opening, you will have a tuning that eliminates the feeling of acceleration.
You will get better fuel economy.
The following is a story from when I was a beginner.
I once tuned the engine to aim for partial throttle of 13.0.
When you twist the throttle to accelerate quickly, you end up with a lack of power.
That is tuning that is kind to the earth.
You can drive normally. Acceleration is decent as well.
I was unaware of the acceleration feeling of FCR.
I didn't realize that the tuning was for a lack of power.

If you want to improve fuel economy, turn off the acceleration pump.
The correct tuning for FCR is an air-fuel ratio of around 12.
I set the acceleration pump to start working at 1/2 throttle opening.

Considering fuel efficiency from the difference between forced opening and closing type and vacuum type carburetors

A forced opening and closing type carburetor works by opening the throttle valve to suck up fuel into the carburetor.
A stock-like vacuum type carburetor uses negative pressure to adjust the amount of air-fuel mixture.
It probably depends on the tuning, but if both are tuned to their best,
the vacuum type carburetor will have better fuel economy.
With a forced opening and closing type, the rider has to directly operate the throttle valve, which increases wasteful fuel consumption.

For FCR beginners – Tuning with an eye on fuel economy is okay at first.

If you read up to the above, you can read that there is no tuning that focuses on fuel economy.
To be honest, I think that if you are going to tune with fuel economy as your number one priority, it is better not to use a racing carburetor such as FCR. However, when trying out tuning, it is necessary to some extent to aim for tuning that focuses on fuel economy. The reason is that you will be tuning yourself as you intended.
After eco-tuning, try tuning that focuses on acceleration.
It is also a good idea to try to see if you can solve the lack of power of eco-tuning with an acceleration pump. Eco-tuning is very easy. Just tune so that the air-fuel ratio indicates 13 to 14 in partial. The acceleration feeling will be low. There will be no problem with driving.
The tuning result will have a relaxed feeling.
If you have an air-fuel ratio meter, try tuning with the partial throttle below 12 and you will be surprised at the acceleration feeling.
When the throttle is fully closed to low throttle opening of about 1/8, you do not need to worry too much about the air-fuel ratio.
It is better to prioritize ease of starting, engine starting and idling.

Improving fuel efficiency with FCR carburetors【summary】

I have some doubts about whether tuning improves fuel efficiency. I haven't tested it yet. However, I can say that it has a significant impact on fuel efficiency when it comes to driving.
I don't think of driving based on RPM, but rather on oil temperature. If you add eco-friendly tuning to that, you may be able to improve fuel efficiency a little if you are tuning the FCR for travel.
You will not feel any acceleration, so it will be an unenjoyable motorcycle.
You are probably installing the FCR for the purpose of increasing power in the first place.
You will not know what you are doing.
I feel that eco-friendly tuning improves fuel efficiency a little.
However, it did not improve fuel efficiency as much as I expected.
In my current opinion, I think that the most effective way to improve fuel efficiency is to drive in a way that does not raise the oil temperature.
There are days when the temperature is suitable for riding a motorcycle.
Don't forget to do maintenance for spring.
See you again!

CBX1000 – Photo Gallery

We have selected some photos from past posts of people touching the slow jet and are posting them here.