Project: Zephyr 550 w/ZX6R Front End Conversion

Some of you have followed my progress on this, and know that there is another thread here with some details about it, but another relevant thread was deleted in a forum update/cleanup. And so I thought that I would post about where it's currently sitting, as I do have some exciting news. 

So the goal has always been the same, fitting a set of upside down forks to my Zephyr 550. I could argue that it's about performance, because I will be gaining three-way adjustable modern cartridge forks, and four-piston radial-mount brake calipers. Technically, an improvement. But I'll be honest and tell you that the main motivation has always been that it looks cool. I got into motorcycling when the modern version of a cafe racer resto-mod was all the rage, and upside down forks were a must. At one point I decided it was too much hassle and not worth it considering my all-original bike was in great shape. Then I got rear-ended and had to rebuild the bike on a salvage title. Figured since it was never gonna be a fully clean title bike anymore, might as well do what I want with it.

It's been a challenge, and I have wanted to give up multiple times. But it became a thing of finishing what I started, and doing it because I set down this path. I had a goal, and along the way other goals have surfaced, but seeing something through, seeing it finished, is one of the things that keeps us going. I'm here now and it is still not done, but a significant portion of the project has been invested in, and will see the light of day soon enough.

While many of these kinds of conversions have been undertaken by others, I took a slightly different, and undoubtedly more difficult path. My version was to create it such that it looks factory, and not hardly custom at all. Keen eyes will no doubt recognize that the forks and brake calipers didn't exist in 1990 when my bike was new. But if I could retain as many original components as possible, including the front wheel, brake rotors, fender, headlight, gauges, turn signals, etc., maybe I could pull it off. The issues... were numerous...

There were few off-the-shelf components that would make this a simple plug-and-play situation. I have sourced a custom axle from Spec Engineering in Japan via Webike, made custom rotor spacers via SendCutSend, determined that bearings, axle spacer, and speedometer drive from a ZX-600, and rotor bolts from a Suzuki would work, had a fully-custom left side axle nut made, and rebuilt the '03 ZX6R forks with (again, fully custom made) damper rod extensions. Here are some photos in probably non-chronological order.



You can see in some of the pictures that I have 3D-printed prototypes of custom triple trees. The biggest part of this project has been designing, prototyping, redesigning, prototyping, and ultimately finalizing a design for custom triple trees. This was done because again, there was no off-the-shelf option. I wanted to maintain the exact steering geometry and wheelbase of the bike. In order to do that I came up with my own design for triple trees, modeled after a hybrid of the stock parts, sized to fit the larger forks, with some design elements pulled from the donor front end's lower triple. The upper triple includes a 10mm drop, which serves to lengthen the forks, and allow clearance of the fork caps under the stock handlebars. 

 

The big news is that the triple trees are officially bought and paid for, and being made by none other than Cognito Moto, arguably the industry's leading shop and experts on custom triple trees. Currently I am just waiting. There is still a lot to do. I'll need to measure for and order custom brake lines, and design and fabricate a mount for the gauges/headlight/etc., as well as sort out whatever I'm gonna do for the front fender. But with fingers crossed I'm hoping maybe it'll be done sometime this year... and then I get to install a big bore kit. 

As a fellow "Sunk Cost Enthusiast" let me say nice work and bravo for sticking through till the end. If it was easy everyone would do it.