FCR Tuning – The tuning of the BITO is excellent when shipped!

FCR Tuning – The tuning of the BITO is excellent when shipped!

The other day, I called BITO to inquire about a custom FCR jet.
About 6 months ago, when I ordered the jet, I was told about the initial tuning of the FCR.
*Please note that the truth of what is written on the Internet is not certain.

It is possible that I have misheard the tuning details below...

[CBX1000 factory tuning]

BITO factory tuning
SJ-40
PS-1.45 minutes back
AS-1.30 minutes back
JN-90FXM#3
MJ-130

I wondered how they thought about the tuning and shipped the above.
As for the jet needle, it seems that it was changed over the course of 20 years from

90FTM
→
90GTM
→
90FXM (custom order).

If they answered the phone clearly, it means that they must have stored the data for each motorcycle so that it is clear.
It may have just happened that the person who answered the phone was knowledgeable only about the CBX1000.
At least when it comes to the CBX1000, tuning is carefully considered at the time of shipping.
BITO also sells aftermarket parts for the inside of the CBX1000 engine.
There is a lot of know-how regarding the CBX1000.

Tuning at the time of shipment is important

I feel that the tuning of the FCR at the time of shipment is a little insufficient to ensure a comfortable ride when installed on a motorcycle.
Rather than tuning, subtle adjustments are required depending on the individual differences of each motorcycle.
The tuning of the BTIO at the time of shipment is excellent.
Touch the AS and PS to check the starting performance, and if it is not working properly, replace the slow jet.
There is no need to replace the jet needle.
Test drive and check the clip position.
If you change it about three steps from the appropriate clip position, it will clearly not work.
After that, find a main jet that seems just right at about 1/2 to 3/4 throttle opening.
Finally, ride at full throttle to check that the main jet number is satisfactory.
That's the process.
Tuning a carburetor is an AB test, so it's difficult to proceed without something to compare it to, and
if you don't know what the good condition is, you can't judge whether the tuning is slightly better or the best.
I tuned the clip position to #1 or #2 lean.

The current tuning of my CBX1000 is
SJ-48
AS-1.20min
PS-1.00min
JN-90FTN#1
MJ-125
.
Seasonal elements are included. The acceleration pump starts working late after 1/2 throttle opening.
JN-90FXM#3 = JN-90FTM#1
is equivalent, so I wanted to make the straight diameter slightly leaner, so I set it to
JN-90FTM#1
→
JN-90FTN#1
.
The slow jet is rich, which is my preference.

What about second-hand or recycled FCRs?

The above discussion assumes that you have purchased a new FCR as a dedicated item.
It is highly likely that this does not apply if you have purchased a second-hand item or if you are using a reused item.
Second-hand items are generally either old FCRs that have not been used much or FCRs that have been overworked and are really no good. If you can get an old FCR that has not been used, you may be lucky if you can overhaul and clean it yourself. In general, gasoline will stick to it, and just removing the rust will make it perform great.
If it is really no good because of overwork, it may be that the body is scraped and a repair kit is introduced, or the gasket of the non-disassembly part is melted. Since FCRs are racing parts, it will be in perfect condition if you replace the deteriorated parts. However, considering the time it takes to replace parts, it is a questionable purchase unless you are interested in it.
If you ask a custom shop to repair it, the labor costs will be quite high.
It is highly likely that you will get better results if you buy a new one.
Unless you are prepared to enjoy working on it yourself, it may be better not to get involved.

FCR for beginners – How to tune it initially?

This is assuming that the pre-tuning is excellent when it is shipped from the factory.
If you don't have any tuning tools or jets, you can get going by adjusting just three things.
1. Adjust the PS to adjust the engine's starting ability.
2. Adjust the AS to adjust the starting ability from clutch engagement at a throttle opening of 1/16 to 1/8.
3. Set the clip number to your preferred position.
You can then start driving right away. At this point, it's questionable whether the performance has improved since changing from a vacuum carburetor, but at least you can get a feel for the forced opening and closing carburetor.
It's a bit questionable whether the performance will improve by a surprising amount, but at least a new function has been added that allows you to enjoy tuning it yourself in a strict manner.
Try tweaking it around, such as synchronizing it, replacing the main jet, and replacing the lip seal after a year.

FCR Tuning – The tuning of the BITO is excellent when shipped!

If you can trust the pre-tuning at the time of shipment, it may not be difficult to start running with FCR. At least, carburetors are devices that will not evolve significantly from now on.
If you search for information, you will find a considerable amount of it. Parts are also easily available.
It is not a situation where you have to grope around and find out what is right like 20 years ago? You will not be at the mercy of magazines.
Racing carburetors can be purchased without any worries as of December 2022. We do not know what the situation will be like in another 10 years. It may be a good idea to install a racing carburetor such as FCR now and play with your motorcycle. We hope you all have a fun motorcycle life.
See you again!

CBX1000 Photo Gallery

I've selected some photos from previous posts where the exhaust pipe stands out.
The exhaust pipe and head of this motorcycle have a prominent design, so they stand out in every photo, but these are mostly close-up shots or shots looking up.