CB550 Cafe Interceptor - Gentleman's Roadster

FunJimmy

FunJimmy

Been Around the Block
Café Interceptor

My CB550F project started as a suspension and brake upgrade that could have easily been completed with a simple modern fork swap and a couple of new rear shocks. Problem is, as soon as I got started searching for donor forks my head began to swirl with a bunch of other ideas and I needed to make a plan before things got out of hand.

The “NEW” plan was to build a factory Works 550 Café Racer inspired by HRC. That meant keeping the stock frame with the exception of the passenger foot pegs and centre stand. I also felt the bike needed to retain all the styling cues of the original street version including tank, side covers, fenders, headlight and signals. Any additional billet aluminum and carbon fibre parts should be understated and have a factory appearance.

To complement the project the engine received 59mm Yoshimura high compression pistons, 1mm over size valves, high performance valve springs, stage III intake and exhaust ports, Yoshimura Daytona (rare) camshaft and Keihin CR26 carbs exhausting spent gasses through a full stainless steel Hindle 4-2-1 exhaust system.

The paint scheme is reminiscent of the early Honda V45 Interceptor, hence the name Café Interceptor.

This project has been a huge success. The bike looks and handles better than I could have hoped for and more importantly it challenged and taught me so much more than I'd ever imagined.

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Re: CB550F Interceptor

It only took the first ride to realize that priority number one was front brakes and suspension.
These may have been state of the art in 1977 but in this day and age, safety and control have evolved into much, much more.


Before I started tearing the bike apart, I built a nice solid wooden pedestal to raise the bike about a foot and a half off the ground.

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Re: CB550F Interceptor

With that in mind I began searching for a modern fork assembly that would provide fully adjustable sport suspension without sacrificing the vintage look of the bike. Several late 90’s and early 2000 sport bikes where spec’d with conventional cartridge forks and after combing through them, I found that the 1999-2002 Yamaha R6 fork assembly was just about perfect.

Motorcycle geometry is quite the science, and I don’t profess to be a expert here, but searching the internet will provide lots of reading about the effects of rake and trail on the handling characteristics of motorcycles. What I did learn is that less fork offset equals more trail, and more trail will provide greater high speed stability at the expense of fast light steering. The CB550 is well known for it’s neutral and agile handling, but this bike is (hopefully) going to need stability cause I want to turn it up a bit on the twisty bits.

The R6 triples have approx. 3/8” less offset than the CB550 triple and should provide slightly more trail and high speed stability.

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Re: CB550F Interceptor

Jimmy,
It's good to see your on this site. Your information and build quality are great and very valuable. Have there been any recent updates to the Interceptor?

Jens
 
Re: CB550F Interceptor

The Yamaha lower triple is forged aluminum with a tapered and anodized steer tube. The steer tube diameter at the upper and lower bearings is 30mm whereas the CB550 steer tube diameter is 30mm lower and 26mm upper. This means that the Honda CB550 head bearings won’t fit. Thankfully All Balls Racing (www.allballsracing.com) can supply a custom selection of taper roller bearing to fit a multitude of different forks on our old bikes.

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Re: CB550F Interceptor

As soon as I received the bearings from All Balls Racing I assembled the triples to check for clearances and was pleasantly surprised at how well it all went together.

The R6 steer tube is just about the perfect length for the 550 frame.

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Re: CB550F Interceptor

To ensure the longest possible bearing life, the bearings must be protected from the elements.
This alloy bearing hood, covers the exposed bearing and extends ¼” over the head tube for a clean finish.
Anodized black and it’ll look factory!

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Re: CB550F Interceptor

If you really wanted to make this an easy project, use the Yamaha R6 front wheel and brakes and it’s almost road worthy.
All you would need to get back on the road is some headlight brackets (these are Buell M2 Cyclone items), clip-ons (many available for 43mm forks), a bracket to mount the tachometer (currently no mechanical speedo drive available) and off you go.
You can see this front end fork swap only requires one custom made piece.
Many of you will have other ideas to make a bearing hood, but if you had one spun out of aluminum it shouldn’t really cost all that much.

1009YamahaR6ForkConversion.jpg
 
Re: CB550F Interceptor

Fork stops are typically only required for parking and some tight lock to lock turns.
Most of us know not to smash the bars into our tanks, but stops should be provided, and I wanted to make a fork stop that didn't require welding to the frame.
If you look closely you will see that the metal stop is bolted to the factory fork stop and can easily be removed and replaced with a different unit if required.

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Re: CB550F Interceptor

At this stage, the Yamaha R6 front fork assembly is pretty much mounted and ready to go, but decisions about the front wheel and brakes still need to be sorted out.

As mentioned earlier, using a Yamaha R6 front wheel and brakes would be easy and get this bike back on the road right away, but I’m after that classic vintage look, so let’s try using the stock CB550 hub and a spoke wheel first.

To do that, there are a couple of architectural issues to sort out. First, the R6 front forks use a large 22mm flex free axle to keep the wheel following a straight and precise path but the CB550 hub has a 15mm axle so larger bearings will have to be accommodated.

Secondly, motorcycles with spoked wheels use brake calipers with pistons on the outboard side only due to spoke clearance issues, and I want modern braking performance with only one disc to keep the stock look, so a 4 (opposing) piston caliper and floating disc would be ideal.

Another consideration is mounting a modern 300mm floating brake rotor. All of these goals can be accomplished by machining two large spacers to sandwich the front hub.

The spacers would be the diameter of the CB550 front hub/disc mating surface and as thick as required to provide clearance for the caliper with ’95 – ‘98 Honda CBR600 F3 rotor mounted. Honda CBR600 F3 rotors have a very similar 6 bolt pattern to the CB550 hub and have a substantial offset which will provide some of the clearance needed for the caliper.

Something like these!

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Re: CB550F Interceptor

With the hub removed from the wheel, I chucked it in the lathe and machined the hub to accommodate the spacers. This hub will now accommodate any size axle and any rotor as long as the spacers are machined correctly.

Photo of a stock hub before and after machining.

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Re: CB550F Interceptor

Hub complete with billet aluminum spacers and a ’95 – ‘98 Honda CBR600 F3 rotor mounted.

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Re: CB550F Interceptor

Here’s the wheel laced up with an Akront 2.5”x 18” alloy rim, stainless spokes and a meaty 110/90-18 Bridgestone BT45V tire.

1017FinishedWheel.jpg


1018FinishedWheel.jpg
 
Re: CB550F Interceptor

There is a much more aggressive look and feel to the front of the CB550F now that it’s all put together. Once the brake caliper is mounted I’m going to be working on a front fender.

I really like the sleek look of a ‘78 Suzuki GS750 fender, but they are too narrow for the 110/90-18 Bridgestone BT45V tire so I will have to cut my teeth at fiberglass fabrication.

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Re: CB550F Interceptor

The Brembo 4 piston monobloc calipers found on the Yamaha R6 are real nice. These calipers are very light and extremely rigid, but fairly thick from side to side and left as is they will hit the spokes of a laced wheel. Milling the caliper mounting tabs and the back side of the caliper will provide all the clearance needed.

Turning parts on the lathe is pretty easy when you have access to a good lathe, but milling is be a little more challenging when the milling operations are performed on a drill press fitted with an inexpensive compound slide table and an end mill.

Careful measurements to provide true, level and square setup will ensure that the brake pads contact the rotor evenly.

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Re: CB550F Interceptor

Milling the mounting tabs 3mm to move the caliper closer to the fork leg will provide most of the needed clearance.

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Re: CB550F Interceptor

After milling 3mm off the R6 caliper mounting tabs the tabs are still as thick as the mounting tabs of this Honda RC51 caliper.

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Re: CB550F Interceptor

The other trick to providing clearance is to mill the back of the caliper at the same angle as the spokes to achieve added clearance.
Being unsure of how much material there is to mill without breaching the piston bores, I had to sacrifice a caliper to research.

As you can see there is almost 6mm of material on the inside of the caliper before hitting the piston bores.

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