I am the owner of a Honda motorcycle [CBX1000] who lives in Hiroshima City, Japan. I am posting about FCR carburetor and CBX1000 customization. I also post about things other than cars and motorcycles. We will post information that will make bikers around the world happy.
FCR Tuning – Jet needle changed to 90FTN. I was concerned about the straight diameter – 2022-11-15
I went for a test run. The purpose is to check whether the straight diameter of the jet needle is good or bad at low throttle opening. I've been selecting a jet needle for the slow jet 48 for a while now.
I tested it with the following.
[Slow jet 48]
①90FXM#3
②90FTM#1
③90FTN#1
④90FTR#1
① and ② are different in the cut-up, so it seems like it's okay to use the same jet needle.
②I decided on ③, which is leaner.
As for ④, it felt good when I made the slow jet a little larger, like 52.
I used to tune it by switching between 90FTQ#1, 90FTR#1, and 90FTS#1,
but now I'm thinking about switching between 90FXM#3 and 90FTN#1 in winter and summer.
The default jet needle for the CBX1000 FCR is 90FXM.
In the summer, it seems like it's okay to prioritize 90FXM#2 and use or not use 90FXM#1. In winter, adjusting the air screw and pilot screw to around 90FXM#3 or 90FXM#4 will improve performance. For my own knowledge, I change jets if I notice anything.
After a test run, this tuning accelerates so well that I don't want to touch it for a while.
It accelerates even if the throttle is handled quite roughly.
It doesn't bother me much if the gears are rough either.
I'm reflecting on the fact that it would be less time-consuming to adjust the straight diameter or clip stage number rather than tuning the low throttle opening while changing the slow jet.
When I first started tuning the FCR, the first jet needle was 90FTM.
After going around and twisting it, it's now 90FTN, so it's almost the same as when I started.
I'm in a state where I'm making the slow jet larger due to my own preferences or the machine conditions.
Currently, I want to prioritize the acceleration, so I prefer to use larger slow jets and main jets. For low throttle openings, I also slow down the accelerator pump's discharge timing and reduce the total amount discharged. It comes down to my riding style and preference. There are moments when the accelerator pump is working and the bike is bumpy. You can adjust this by adjusting the throttle work, but I like to handle it roughly. I like the feeling of acceleration with rough throttle work. I slow down the accelerator pump. Adjusting the accelerator pump is also a challenge.
Test run impressions
I felt that it was so good that I wanted to keep it in this condition forever. I always tune it until it is better than the last time. It's only natural that it feels good. Currently I don't use the acceleration pump at low throttle openings. I tune it with the idea that it would be good if I could get a sense of acceleration without using the acceleration pump. I have the main jet a little lean. Checking the past logs, I saw that 132 was also good. My test runs for tuning are mainly on public roads. I choose a size that gives a good sense of acceleration at about 1/2 throttle opening. For the main jet, I check the sense of acceleration when riding at full throttle on the highway. I haven't tuned it at full throttle many times. There is room for fine-tuning. I also recently got a diaphragm for the KX400 for the acceleration pump. I'm thinking of trying to find my favorite discharge timing in 0.6mm increments.
For FCR beginners – It may be better not to touch the slow jet when tuning
As I have mentioned before, Japan is an area where the temperature difference between seasons is large.
Changing the slow jet is an expensive job.
Once you have decided on the slow jet, you should not change it for a while and instead adjust it with the jet needle and screw. This will reduce time costs and the chances of encountering unnecessary trouble.
The slow jet and jet needle balance each other.
It is easier to make fine adjustments by fixing one and changing only the other.
Changing the jet needle is a low labor cost.
If the appropriate straight diameter has been decided, you can prepare for tuning by preparing jet needles with straight diameters that differ by one step at a time.
It is better not to spend time and effort changing the slow jet, especially if you are a beginner.
Changing the jet needle is one way to solve the problem.
If you have a CBX1000, the 90FXM will be fine all year round. If you adjust the clip stage and screw according to the season, you can ride well.
In addition, even if you tune the 90FTS with the slow jet set to 52, you can handle it all year round with one jet needle. In previous FCR sections for beginners, I assumed that you didn't have all the tools and jets, but this time I've written it assuming that you have purchased a jet needle. It's not easy to find someone who can teach you how to tune an FCR. Beginners' only source of information is knowledge they can find online or reading magazines. By the time you get used to it, you're no longer a beginner. The hardest part is being a beginner. You'll manage if you try. If you're thinking about getting into FCR, go for it with a spirit of challenge.
FCR Tuning – Jet needle changed to 90FTN. I was concerned about the straight diameter – 2022-11-15【summary】
This year I changed the jet needle tuning and did various test runs. I learned a lot in the process. Next I plan to try various things with the main jet and accelerator pump. Winter is almost here. It's the beginning of a difficult season to ride a motorcycle. Depending on how you look at it, it's a fun season because you can wear a leather jacket. However, I don't like the cold. Some riders ride their motorcycles without giving in to the cold. Some riders do maintenance in winter. I am a rider who does maintenance in winter. I haven't been riding my motorcycle as often lately. When you do ride your motorcycle, please make sure you dress warmly. See you again!
*I will add a photo gallery of the CBX1000 at the bottom.
CBX1000 Photo Gallery
It's nice to see photos with a clear blue sky. The atmosphere of Caddy Red changes greatly depending on the brightness of the day.
