FCR-How to fix overflow

FCR-How to fix overflow

FCR overflow. This is a symptom of gasoline leaking from the carburetor.
I will write about the disassembly in the second half.
I'll write how to fix it first.
① Hit or shake the FCR.
②Drain the gasoline from the drain bolt once and move the float.
③ Spray parts cleaner on the fuel line to clean it.
④Replacement of rubber packing
⑤FCR OH

Normally, ① to ③ will be enough. I'm writing this roughly, so it's not perfect, but
Overflow does not occur when the carburetor is broken, but when it is clogged with debris.
Since this is the correct operation, where does the garbage get stuck?
If you keep these things in mind, you will be more likely to be able to deal with unexpected problems.
*Rather than correct operation, if it is working correctly and has no deterioration, if it overflows,
If you just look at the float valve, there is a high probability that it will fit.
Unless the motorcycle has been abandoned for a long time, 90% of the time the carburetor is not broken;
It's just filled with small debris.
There are many cases where the same thing can be said about other carburetors other than FCR, so sudden overflow occurred.
Riders of old motorcycles will benefit from knowing how to deal with the situation.
Knowing how things work in advance will be helpful when dealing with them or disassembling them for the first time.
Additionally, most people who ride carburetor motorcycles have had them for over 20 years. You only need to do it once, so check how to remove the chamber at the bottom of the carburetor.
Please try opening it. In that case, please turn off the cook.
This time I will write up to ③. Regarding ④ and ⑤, it is necessary to order parts in advance,
I will post again if I have a chance.
By the way, FCR requires no overhaul and you don't have to drastically change the tunings.
I have been able to drive it for several years and thousands of kilometers without any trouble. I will write about the area around the float valve.
Once you know the words, you can look them up separately, so you can also look up information written by other predecessors.
Please refer to it.

FCR-Float valve

Carburetor overflow is usually caused by gasoline leaking from the air vent in an FCR. Unless you turn off the cock, the gas will gush out forever. Depending on how clogged the garbage is, gasoline may come out quite forcefully.
Although I write it as if there is only one cause, there are many causes.
However, this description is based on the assumption that 90% of the float valves have dirt attached to them.
First of all, please remember just the float chamber and float valve.
The bottom part of the FCR that stores fuel is called the float chamber.
When fuel accumulates in the float chamber, the float valve
It acts as a plug that stops the fuel supply from the fuel line.
If small particles adhere to the float valve when it closes, it will not be able to close the fuel line properly, causing gasoline to spray out. That's what causes the overflow.
By the way, I don't know the lifespan or replacement period, but there are some motorcycles that can last 20 years without any changes.
If you have a chance to remove the carburetor, you can replace it at that time.
The price is not that high, and it is about the same amount of effort as changing an SJ slow jet.
The only adjustment required is to align the height of the fuel surface.
It is difficult to adjust the height of the fuel level to the ultimate level, but the manual specifies highly accurate adjustment.
There is no description that says to do so, so please measure the height before replacing.
There is no problem with driving as long as all cylinders are aligned after replacement.
By the way, it is better to set the fuel level as high as possible without overflowing.
Too low and you will run out of fuel.

When the black part at the tip of the float valve becomes hardened or scratched, it is at the end of its service life.
If the spring on the back side of the float valve goes flat, it is also at the end of its life.
If dirt adheres to the black part at the tip of the float valve, the probability of an overflow will increase. It is not something that will break or wear off under normal use. It's priceless,
If you touch the area, it is better for your mental health to replace it at least once every few years.

It is posted on YouTube.

The carburetor is upside down. I'm blowing parts cleaner from the fuel line.
If fuel leaks from the float valve, the float valve is not functioning.
The assumption is that gasoline will come out when you move the float (white part) by hand. After installing the chamber, visually check if the fuel line is normal? I don't understand that, so I'll use this as an example to check the operation.
Are the other floats moving properly? There are things to check, such as, is the float valve operating correctly? This is the most difficult point to confirm.

FCR – Fuel efficiency for beginners

I touched on the fuel aspect earlier. The fuel level and jet are thick and thin, the amount of accelerator pump is high and low, etc.
This is likely to affect fuel efficiency.
As I understand it, fuel efficiency does not change depending on the tunings.
We believe that depending on the tunings, the way you drive will change and the fuel efficiency will change.
If you place emphasis on acceleration, you will use a rich ratio of fuel in a partial state with the throttle stabilized.
If you set it to a stable tuning in the partial state, you can only slowly apply the throttle.
It will be a fuel-efficient motorcycle that cannot be opened.
This is caused by the fuel being too lean.
Since FCR is a racing carburetor, it is best to have a feeling of power and revving when accelerating.
The above information is not exhaustive.
The important thing is how to open the throttle.
If the computer does not calculate and feed fuel to the engine like in injection,
It is difficult to achieve extremely high fuel efficiency with FCR.
A good carburetor tuning will improve your motorcycle's fuel efficiency!
It is written in Japanese magazines etc.
There are not enough words for this.
Fuel economy will be better if there is no unnecessary fuel supply due to opening the throttle unnecessarily.

FCR carburetor photo

This is a photo that involves floats and float valves. I had intended to take pictures frequently, but I'm very sorry that some of the pictures are a little short of being useful.
When removing the float chamber, also remove and install the carburetor, and check that the float chamber gasket is installed correctly. It is safer to install the carburetor after checking it. There are cases where fuel leaks from the float chamber gasket, but please note that the cause may also be due to improper installation.

FCR-How to fix overflow【summary】

I wrote it a little sloppily, but some people may find it helpful.
Which air vent? Which is the drain bolt? I haven't written it in detail, but
If you are willing to do the work yourself or are having trouble with related areas,
Please keep your imagination in mind as you read.
I am writing this to reconfirm my history and writing.
The way I feel and express myself is somewhat different between writing written through trial and error from the perspective of a Sunday mechanic like myself and writing written by a seasoned professional. If you hit it at the beginning, it will be fixed!
I wrote it like this, but I don't think it's a mechanism that involves hitting or shaking it.
The quality of troubleshooting is different. When you touch the slow jet with FCR,
This is a problem that is easy to encounter. I often work outside, so
Without you noticing, dirt may get into the jet or dirt attached to the outside of the carburetor may get mixed in.
Currently, I try to touch FCR as soon as I feel like it, so as a reflection point this time,
I'll post again, considering the lack of photos.
See you again!