Installing the CB1100F front-end assembly on the CBX1000

Installing the CB1100F front-end assembly on the CBX1000

Installing the CB1100F Front End

I’ve found some past photos, so please take a look through this journey with me. Currently, I'm very pleased with the CB1100F front end setup. There are several reasons I chose the CB1100F: I wanted to use the original “Robo” handlebars, have a thicker front fork, and keep the modifications to a minimum.

There are several advantages to using components from another model. The biggest benefits are fewer modifications and the ability to use aftermarket parts as they are. When considering long-term disassembly and custom machining, it can be challenging for a DIY enthusiast to incorporate new aftermarket parts. The front end, from the triple tree down, can be transplanted almost without modification. The only machining required was to adjust the stem shaft length.

The CB1100F only has the model code SC11, though there may be slight variations depending on the export market. The CB-F series shares many common parts in the front and rear ends, so I hope you’ll find this informative.

Now, let’s dive in!

Note: The CB750FC and CB900FC likely have equivalent front and rear end specs.

The CB-F series offers a variety of options for front and rear ends.

Models without TRAC

I'm going to continue the discussion by including the CBX in the CB-F series. There may be some incorrect information, but some of the details are based on the parts I have on hand, so I’ll also be sharing accurate information.

As for the front forks, it seems there are 35mm, 37mm, and 39mm options. Only the 35mm fork has both air suspension and non-air suspension versions.

Here are the details for each model:

CBX1000 (Model: CB1)
35mm front fork, no air suspension

CBX1000 (Model: SC03)
35mm front fork, with air suspension

CB900FB 
Year and model details unknown, 37mm front fork, with air suspension

CBX1000 (Late model with fairing, Model: SC06)
39mm front fork, with air suspension

As you can see, the 39mm front fork assembly from the SC06 model is traded for very high prices. When these parts appear at auctions, they generally get bid on and are successfully sold.

TRAC有

The Honda version of anti-nose dive is TRAC.
https://www.honda.co.jp/factbook/motor/VF750/19820300/011.html

I have confirmed that the 39mm front fork comes with TRAC. While I haven’t confirmed the 35mm and 37mm versions, they likely do not exist with TRAC.

This is a part that tends to divide opinion, but generally, more people dislike it. At low speeds, there is an unintended, jerky feeling. When pushing or pulling, the fork becomes stiff, making it difficult to compress and extend properly.

In terms of looks, it’s a mechanically complex and cool-looking front fork. It’s nearly 40 years old now, so compared to modern forks, it is undeniably outdated.

Vehicles with TRAC are found in the CB-F series. Among them, the CB1100F and CB1100R have stabilizers and initial adjusters at the top of the fork. The front fork length also seems to be longer. The triple tree length is also different. When swapping these forks onto a CBX1000, the center shaft needs to be replaced.

As an option for reuse

This blog is about the CBX1000. My CBX1000 is model CB1. The twin-shock CBX1000 models CB1 and SC03 are the ones covered in this post.
Note: Some models from the CB-F series are also relevant.
The SC06 model has a 39mm front fork, so it doesn't need to be swapped out.
For the CB-F series, the options for high-performance front forks are the CBX1000 with fairing (SC06), CB1100F, CB1100R, and CB750FC. This makes it effectively three options.
For the CB750FC, the lack of stabilizers and adjusters is a disadvantage. However, there are things you can do precisely because of this.
You can extend the front fork. Adding aftermarket stabilizers could give it a cool look.
Whichever option you choose, there are advantages to be had.
One of the benefits of using parts from other models is that it helps maintain the balance of the motorcycle.
If you swap out the triple tree without careful consideration, it could make the bike difficult to ride, or it could result in the meters being positioned in a way that looks quite unappealing.
For the CB-F series, changing the angle of the meters or the position of the headlight too casually can make the bike look really bad.

Precautions when reusing parts

When reusing parts from the CB1100F and CB1100R, the length of the center shaft on the triple tree is different, so it is necessary to replace it.
However, it can be easily swapped out.
The air balance pipe is also mounted on the triple tree, secured by screws in a hanging position.
The wheels can be used directly as long as the shaft and spacer are in place, as the hub diameter is the same.
However, parts like the front fender cannot be used as is and require some minor modifications.
The brake calipers are the same 4-pot calipers for both, so they are interchangeable.

The welding at the bottom of the stem shaft can be cut using a grinder, and the center shaft can be removed by using a press.
As long as you have the right tools, the removal and installation should not be a problem.
Motorcycle shops or similar establishments should have the necessary equipment.
You can also contact them to inquire if they can assist with this for individual DIY projects.

Precautions when purchasing used parts for repurposing

The target models are the CBX1000 [CB1] and [SC03].
Except for the wheels and brake discs, everything else needs to be purchased.
The parts that can be used for both the later model CBX1000 and the CB1100F are the same.
For the brake calipers, everything including the brackets is required.
Regarding the discs, the SC06 standard comes with ventilated discs.
The offset and diameter of the disc are the same, so regular brake discs can also be used.

Most people will likely purchase from auctions.
When buying the front end, you should be prepared to sell off any unnecessary parts through auctions.

Since the premise is modification (repurposing), please avoid purchasing high-priced OEM parts.
It may be cheaper and provide better performance to buy aftermarket special parts or new OEM parts from other models.

before or after

I found some photos for comparison, so I will include them.
The "before" is the 35mm front fork from the CBX1000 [CB1] model.
The "after" is the 39mm front fork from the CB1100F.

before

With my skills and sense, I couldn't feel any difference.
Honda changed the front fork size from 35mm to 39mm in the later model.
This means that the 39mm front fork was the appropriate size for the CBX1000.

after

The CB1100F front fork has been installed.
It has been upgraded with features like a stabilizer, an integrated air balance pipe, and an initial adjuster.
The air balance pipe is secured with screws.
A downside is that the front fork's protrusion and length cannot be adjusted with adapters or other means.
In this regard, the front fork from the CB750FC is more practical.

Characteristics of the CB1100F front end

In terms of performance, it has been mentioned above, so I will focus on the appearance.
Compared to the CBX1000, the number of parts has increased, giving it a more mechanical impression.
The stabilizer, air fork balance pipe, and other integrated components create a sense of unity, and it looks cool.

I have also added details about the custom work I did.
The black parts have been painted with a glossy black finish.
The bolts are all silver-tone, where possible.
I have used titanium bolts as much as possible.

I customized the hidden parts with aftermarket parts.

The front axle shaft has a different length between the 35mm and 39mm front forks.
The hub diameter of the wheels is the same.
I’m using aftermarket parts for the axle shaft.
For the fork springs, I’m using aftermarket parts as well.
The speedometer gear is the one for the CBX1000 [CB1].

Restoration of the CB1100F Front Fork

The front fork inner tubes were re-chromed, which cost around 40,000 yen. The springs used are Hyperpro's CB1100F-specific springs, and I have set the oil viscosity to 15 weight, with the oil level set at 150mm.

The weight difference between the CBX1000 and the CB1100F seems to be around 30kg, with the CBX1000 being the heavier of the two. While the comparison between the 35mm front fork and the CB1100F fork isn’t based on both being in perfect condition, I can say that switching to the CB1100F fork was definitely worth it, especially on descents.

It could be the effect of TRAC, or perhaps just a placebo effect. While the performance can’t be considered high, the front and rear ends, after being overhauled, provide a very pleasant riding experience.

If you choose to proceed with a swap or modification that doesn’t quite fit, it’s best to install aftermarket parts.

It is possible to fit the latest Ducati front and rear ends onto a CBX1000. However, doing so would require significant time and cost to fabricate custom parts to make everything fit properly. If you are considering a forced swap, it's best to go with aftermarket special parts instead.

One viable aftermarket option is the dedicated CBX1000 kit sold by BITO, which is specifically designed for this model. Using modern used parts or incompatible swaps often results in a motorcycle that becomes difficult to ride.

Balance during riding

My CBX1000 is customized with the front end from the CB-F series, with the expectation that it won't drastically affect the balance during riding. The following is my interpretation of ideas from magazines and online sources written in the past decade. According to modern thinking, frame reinforcement is typically unnecessary.

When it comes to cornering, the key factors are the front fork offset and length, which determine the trail. The offset of the CB-F series front fork is likely 45mm. The manual for the CBX1000 lists the trail as 120mm. I have adjusted the rear suspension length to compensate for the added length of the front fork. If I were to change to an 18-inch wheel, the rear suspension length would need to be shortened accordingly.

Installing the CB1100F front-end assembly on the CBX1000【summary】

The CB-F series front end swap can also be done with small modifications using parts from the GSX1100S KATANA. However, using the CB-F series front end offers a greater advantage in maintaining balance. Even for minor swaps, the cost of restoration, including repainting and replating, can quickly add up, often making the total cost quite substantial.

Instead of purchasing 40-year-old used parts, it may be more beneficial to invest in special parts from manufacturers like BITO or Öhlins, which could lead to better results. If you make the wrong choice in parts during a swap, it can turn out that installing aftermarket special parts would have been a more affordable and effective option. On the other hand, even with special parts, there's always the possibility of the balance being thrown off, resulting in a bike that is harder to ride.

With that in mind, the most important condition when customizing is not to disrupt the balance. When installing special parts, you need to approach it with the mindset of replacing all components on both the front and rear wheels at once.

As for my own CBX1000, I anticipated that the front end swap would still be within an adjustable range, even if the balance were affected. Changing from 35mm to 39mm front forks was a modification I had always wanted to try. I expected it to take more time due to possible complications, but the process went much more smoothly than I had imagined. The work included swapping the brakes as well.

Rather than feeling like a full customization, it was more like a simple parts replacement. Although many parts were swapped, I didn’t encounter any issues with delays or missing components. If you're considering installing 39mm front forks on your CBX1000, I encourage you to give it a try.

If you’re looking to completely fill your front and rear ends with special parts, BITO's kit is also an option worth considering.

Take care, and see you again!