Work at the rental pit – 2023-03-24 – Removal of FCR carburetor. Removal of throttle valve.

Work at the rental pit – 2023-03-24 – Removal of FCR carburetor. Removal of throttle valve.

Winter Maintenance Work on the CBX1000

I’m gradually progressing with the work at the rental pit. It's better than not making any progress at all. I tried to get as much done as possible, even if it was just for an hour.The tasks completed so far include the removal of the FCR carburetor and the throttle valve inside it. Although it doesn’t feel like a big step forward, the goal is to replace the lip seal and the Vacuum release plate, which has been in use for 20 years. I also plan to replace the insulator with a new one.These parts are subject to aging and are recommended for periodic replacement. However, the current lip seal, Vacuum release plate, and insulator still seem to have a few more years left in them. I even feel like replacing them with new ones might cause unexpected issues.But it’s probably better to replace them on a schedule rather than waiting until they fail, to avoid potential trouble.Now, let’s begin the work.

First, I’ll remove the FCR carburetor.

If you're not used to it, take a picture of where the throttle cable barrel (taiko) was positioned before removing it. If the work involves many steps, it might be a good idea to cover the intake openings with masking tape or something similar to prevent foreign objects from entering. During the work, it’s not just about dirt getting in; bolts or washers could accidentally fall into the intake.

When replacing the spark plugs, be careful not to remove or attach other parts simultaneously, as it could lead to serious issues.

I’ll proceed with disassembling the FCR to replace the Vacuum release plate.

First, drain the gasoline from the air vent. Then, loosen the drain bolt to remove the remaining gasoline. Disconnect the fuel hose and separate the FCR into groups of three. Remove the Velocity Stack.

Next, remove the tuning screw and tuning nut. Take out the slide valves. At this point, make sure it’s clear which slide valve came from which position. I mark them with numbers using a marker.

The side position of the slide valves is adjusted at the factory during the shipment of the FCR. This adjustment is secured with a Phillips screw. Do not loosen this Phillips screw.

Now, you can replace the slide valves and the lip seals.

For FCR Beginners – Be Cautious When Replacing Lip Seals

With a bit of research, you'll find that you can replace the lip seals without removing the FCR. The tuning manual does list them as parts that should be replaced periodically. It suggests replacement every two seasons or 32,000 km for small sizes. While it seems more logical to go by mileage rather than time, I'm not entirely sure.

I've never replaced the Vacuum release plate before. And though I've owned my CBX1000 for 20 years, I don't think I've even ridden it 20,000 km. However, depending on the type of motorcycle, you may need to remove the tank or otherwise access the top part of the FCR. Other than being mindful of the orientation, there shouldn't be any particular issues.

Lip seals aren’t particularly expensive. But as I researched further, I found one potential pitfall: synchronization is essential. Since the Vacuum release plate needs to be removed, it’s only natural that synchronization would be required. The lip seal replacement affects the clattering sound of the FCR, so it's an area where you might want to check for changes after replacement. Just keep in mind that synchronization is mandatory.

Even if you don’t use a vacuum gauge to achieve perfect synchronization, there are simple methods, like inserting a cotter pin into the throttle valve to ensure they move in unison. As long as synchronization isn’t significantly off, it shouldn’t cause any issues, and it won’t make the bike undrivable. In fact, most carburetor-equipped motorcycles out there have a bit of misalignment.

For those who have never worked on an FCR and have a motorcycle where tank removal is easy, give it a try. You'll likely notice the need for synchronization. If your FCR has never been synchronized, it’s probably off. Even a visual check and slight adjustment can make a difference.

Work at the rental pit – 2023-03-24 – Removal of FCR carburetor. Removal of throttle valve.【summary】

In terms of work time, it’s less than an hour, but I'm operating under the mindset that even a small step forward is better than none at all. Hopefully, next time, I’ll be able to replace the Vacuum release plate and complete the synchronization work. However, if the battery isn’t in good condition or other maintenance needs arise, I might focus on a different task.

I’ll continue working within the limits of what can be done over the weekend.

See you again!

CBX1000 Photo Gallery

Photos of this work will be posted below.