FCR-Synchronization-Taper Gauge

HONDA CBX FCR FCR
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FCR-Synchronization-Taper Gauge

It's about synchronization. This is the process of aligning the suction strength for each cylinder of the carburetor.
This is a must-do procedure for multi-cylinder engines. The ideal is perfect, but
CBX has two throttle wires and two stop screws, so
When you turn the throttle, there may be slight deviations due to the tension of the wire, etc.
I think it's impossible to match it perfectly.
I try to clear the following two points as a minimum.
① When the engine warms up, the idling does not go up excessively.
② The tachometer returns extremely poorly when racing.
If you can maintain this condition, you will be able to ride properly. .
In addition, the opening of the throttle is the same for the 1-3 cylinder group and the 4-6 cylinder group.
The same thing happens with the 1st-3rd cylinder group and the 4th-6th cylinder group when the throttle is fully open.
I am working on this premise. Since the throttle wire is bifurcated, adjusting the throttle area will result in a large change. Even if it is possible to decide on a perfect condition in rare cases,
When I install and remove the carburetor, the balance gets slightly unbalanced, so lately I've only been adjusting it to the point where I feel it's perfect.

FCR-Taper Gauge

Periodically, I adjust the top screws on the left and right, and use a taper gauge to adjust the opening of the throttle valve so that the height of the synchronization screws is average. The adjustment of the synchronization screw is limited to 0.9mm, so if you repeat synchronization several times,
There will be a limit to what you can adjust. To avoid this, I periodically restart the synchronization from the beginning. By the way, the suction force for each cylinder is slightly different, but if you just match it with the taper gauge, it will be in good condition. Even if it is far from perfect, the following two points,
① When the engine warms up, the idling does not go up excessively.
② The tachometer returns extremely poorly when racing.
As long as you clear it, there will be no problem when driving normally.
While achieving ultimate perfection is important, you should also consider the cost-effectiveness of getting there.

FCR – For Beginners – Fully open throttle valve

Synchronization involves adjusting the height of the throttle valve when the throttle is fully closed to equalize the negative pressure in each cylinder. There is no problem as long as you clear the two items I wrote as the minimum line, and there is generally no problem even without a vacuum gauge. Another thing to keep in mind is that when you open the throttle fully,
Also check that the throttle valves are fully open for all 6 cylinders.
My FCR is an old model, so cylinders 1-3 and cylinders 4-6 are grouped, and the throttle wire is split into two.
It is ready for operation. I try to make sure that when the throttle is fully opened, the throttle valves in both groups are fully open. It is generally adjusted by the tension of the throttle wire.
Even on motorcycles with two throttle wires, one for pull and one for return, it is necessary to get into the habit of checking that the throttle valve is fully open when the throttle is fully open. If you adjust the return force or play of the throttle, in rare cases the throttle valve may not open completely. This can be fixed by adjusting the way the throttle wire is attached, so please check that.
Throttle work is one of the real pleasures of forced opening/closing carburetors such as FCR.
You can tell by looking at it or just by touching it with your finger.
The vacuum gauge is synchronized when the throttle is fully closed, but when the throttle is fully opened,
It is possible that something is wrong... Please make it a habit to always check.
P.S.
Be sure to calibrate the needle before using the vacuum gauge. There may be significant deviations.

FCR-Synchronization-Taper Gauge【summary】

It ended up being a bit of a compromise, but perfection is very difficult.
I'm sure there are many riders who think that if it's just short of perfection, it's possible to do it right away.
What is the acceptable range of accuracy? If you understand this, you will have a good reason to compromise.
I'm not perfect, but I'll try to get it close to perfect.
No one can do it perfectly the first time, and those who don't have the tools will be disqualified from riding a motorcycle.
I hope you have a good FCR life!
See you again!
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