FCR synchronization and 6-series vacuum gauge

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FCR synchronization and 6-series vacuum gauge

This is a carburetor blog article about installing 6 vacuum gauges and making sure to calibrate the meter. I additionally purchased a new 4-gauge vacuum gauge, but it was out of alignment when I opened it and checked it.
If you are using a 4-unit vacuum gauge, you can replace the ones you normally use with numbers 1 and 2.
You can immediately see how much it's off. Until now, I always thought something was wrong when I tuned in.
What's strange is that it was a vacuum gauge.
For the vacuum gauge, two 4-gauge gauges have been slightly modified to have 6 gauges.
There are two 4-strands. There were 8 gauges in total.
The remaining two were sold as individual gauges on Mercari.
Frankly speaking, I think there is no demand for a 6-gauge vacuum gauge.

Things to check – this is important

Check the tension and return of the accelerator wire before synchronizing. When fully open, check to see if throttle valves 1 and 6 open fully at the same time. The tension of the throttle wire allows the two-pronged FCR to match the height of the throttle valve when fully open.
Next is the adjustment when fully closed.
Use a tapered ruler to match the height of the throttle valve to within 0.5mm.
It's about the main alignment. Adjust by touching the tuning screw and tuning nut. The negative pressure is high (the one with a large negative pressure) is set close to 0. Touching either the tuning nut or the tuning screw will change the negative pressure. Check the changes little by little. Also, if you change the negative pressure in the #1 carburetor, the negative pressure in the other cylinders will also change.
If the idling changes during tuning, touch the top screw to adjust the idling to the appropriate level.
When you repeat the above steps and reach a satisfactory state, the synchronization process is complete.
It is desirable for the accuracy of the docho to be perfect, but there are also characteristics of the vacuum gauge, and the engine is a moving object, so I say that the work is completed with an error of about 1 mm on the black scale of the vacuum gauge.
My CBX has a problem with the rpm meter, and it seems to stop for a moment when it returns.
I try not to worry about it because it deteriorates over time.
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Other photos – list and explanation

Negative pressure can be applied manually using a syringe and a vinyl hose sold at home centers. I haven't tested how far it will shift, but I'll keep all the lengths the same.
The vacuum gauge is made by Daytona and can be adjusted by pushing or pulling the shaft at the base of the needle. The lid can be easily removed using a screwdriver.
Push it to calibrate the hands clockwise, pull it to calibrate them counterclockwise.
Even when I'm on the go, I try to proofread before starting work. By the way, I used to use a 4-gauge vacuum gauge for synchronization, but I changed it to a 6-gauge vacuum gauge in consideration of the time required for attaching and dismounting and the accuracy of the work.
When performing FCR tuning work outside, you cannot use a fan, so it may be a race against time.

I carry tools and vacuum gauge drip in my backpack. There are fewer tools than I expected, so tuning and cab tunings are also recommended for women.

FCR synchronization and 6-series vacuum gauge【summary】

It seems that there are some people who don't care about the synchronization. The tuner who repaired my CBX engine told me to keep it in tune. There's no harm in getting the tuning right, so I make sure to re-synchronize at least every time I touch the top screw or attach or remove the carburetor. Also, my FCR is an old type with two accelerator wires, so I try to re-synchronize it whenever I touch the accelerator wires. I tune in deep in the mountains or in a rental garage. Basically, if the oil temperature gets too high deep in the mountains, we will cancel it. As expected, you can't move deep into the mountains with a fan like you can in a rental garage... I start by plotting with a ruler. As an alternative method, some people seem to be able to insert a cotter pin into the throttle valve and then release it at the same time. I would like to make adjustments with a perfect system, but I think it would be okay to roughly match them with a split pin. I didn't realize that the vacuum gauge was out of whack until recently. I think there are many vehicles where the negative pressure is the same on the vacuum gauge, but the actual negative pressure is not.
Well then! Have a good FCR life! See you again!
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