Ducati SBK Nr4

By Walt Siegl of

I built this SBK the way I would have built it for myself, and that’s exactly what the owner asked me to do: Build the bike I would want to own.

In fact, I actually used the engine that Bruce Meyers built for my personal SBK (that I never got around to building). I love Ducati’s long stroke motors, but instead of a big monster Corsa engine, I wanted an engine that is as spritely and responsive as possible, matching the lightness and agility of my SBK chassis.

The idea behind the SBK was to build a machine as agile as possible, that steers significantly better than anything you can buy off the showroom floor. Such a bike allows its owner to become a better rider. Walt Siegl SBK Nr4 2

Because riding well and having fun is what it’s all about. High horsepower engines are not necessarily really conducive to having fun.

That’s why I picked this engine configuration: 848 crank case, lightened and balanced crank with updated crank bearings, titanium connecting rods, 1040 big bore kit with Pistal race pistons, ported and flowed cylinder heads with high lift cams, lightened 1098 gears with open clutch housing. It picks the throttle up like a shotgun blast. The engine breathes through a WSM carbon fiber airbox and ram air tubes.

Suspension is Ohlins all around. Since the bike weighs only 328 lbs wet, the front forks are specially built for the weight of this bike, with lighter springs and custom designed shim stock. The rear shock received the same treatment.

The electronics includes custom made fuel, air delivery, and engine speed map. Traction control and quick shift. I’m always trying to build the perfect machine, but I don’t want to give up the visual clues to the fact that a big part of my bikes are designed by me and built with my hands.

This is always a conversation I have with myself: Which components should carry that visual language of the handmade. I worry sometimes that some streamlined, high-tech looking parts might lose that visual aspect, of all the love and effort that I put into these machines. Also, because of the demands of a race bike, not all components can be made by hand.

The one request the owner had was color choice. He sent me a picture of a Ferrari SP2 painted in a limited color. It’s always a bit tricky to try to transfer color combinations that work on a car onto motorcycles. It’s not always successful. Walt Siegl SBK Nr4 4

Cars, with their big panels, reflect light and show shadows much differently than on bikes, since bikes have much more intricate surfaces. But it was definitely a risk worth taking, and I think it really works for the SBK. The Walt Siegl SBK Nr4 – Specifications

I have made changes to the air box, the air filtration system and designed a new fuel injection system within the air box to create as little air turbulence as possible. I also redesigned the fuel tank to gain fuel capacity and to change the way the air enters the air box. ( to save as much weight as possible, I designed the floor of the carbon fiber tank as the lid for the SBK specific air box). I also did some changes to the structural carbon fiber components within the subframe, which is entirely built with carbon fiber, and now weighs only 3 pounds. I have added additional support for the exhaust headers and muffler. There is no specific donor for the engine. It’s a complete custom built unit. (See description in my last email) The exhaust headers are specifically built for this engine to support rideability without sacrificing full throttle flow. The muffler is titanium with a removable DB killer. Removing it gave me a gain of 5 horsepower but elevates the decibels a bit. The frame design turns the bike into a scalpel. I just recently had a professional racer ride SBK NR 3 on the track and he told Bruce Meyers ( my engine builder) that he has never ridden a bike that steers and finishes turns as well as my SBK.

The fork is Öhlins with SBK specific internals. The shock is a Öhlins TTX model with SBK specific internals. Brembo radial calibers with track pads and Spiegler Performance brake lines built with the SBK required lengths. Yes, indeed All my carbon fiber parts are built now by Indy Perfomance based on my in-house made tooling masters. Ducati Corsa Magnesium upper tripple tree. Ducati bike switches. Brembo RC master cylinders. Ducati 1198S Speedo. Öhlins steering damper. WSM foot controls. Kellermann blinkers.

Source Walt Siegl Motorcycles