SR Archive: Mike Lee's Turbocharged Ducati 900 SP

The Turbo Duck

This article was originally published in the December 1996 issue of Sport Rider.

You might remember a turbocharged, Spondon–wrapped Kawasaki Z1–powered Moto Martin we featured back in our February 1995 issue. High Gear Specialties' turbocharging expert and Sport Rider reader Mike Lee has a flair for creating motorcycles that escape the common pipe, shock and jet kit mods, dipping into territory previously unexplored by even the most open-minded, mod-happy enthusiast. Mike's new turbocharged Ducati 900 SP proudly follows in the footsteps of his previous creations, combining two words most people wouldn't mention in the same sentence: Ducati and turbocharger.

Mike Lee's Turbocharged Ducati 900 SP
Mike Lee wanted even more horsepower for his stock Ducati 900 SP so he did the unthinkable and turbocharged it.Photography by Tim Tew

Lee was attracted to the inherent comfort and versatility of his stock SP, but being a grade-A, government-inspected horsepower junkie meant that he wasn’t satisfied with the horsepower available in stock trim. So with a little patience, money and plenty of ingenuity, Mike successfully mated an IHI turbocharger to the 904cc mill while still retaining the bike’s stock 38mm carburetors and, Mike claims, drivability. A 110-horsepower run on Tony Foster’s Personal Cycle Service dyno made it perfectly clear that this Duck was finally ready to fly.

Mike Lee's Turbocharged Ducati 900 SP's turbo kit
The polished airbox top comes with Lee’s turbo kit, fully pressurizing both the airbox and carburetor. The air enters the turbo and then blows through the carb, thus the “blow-through” description of the turbo. A draw-through system depends on the air to be sucked through the carb and is less efficient and harder to tune for streetable manners, according to Lee.Photography by Tim Tew

Mike Lee has been building turbos since 1979, wringing big power out of two-valve, big-bore Kawasaki KZs at the dragstrip. But Lee’s focus has since strayed toward road-going sport bikes and roadracing, and after installing a turbo kit on his wife’s stock Ducati M900 Monster, Lee decided to apply the same kit to his 900 SP. “The Ducati is light, has good handling and good brakes,” Lee explains, “but it needed more go.” After dyno-testing his turbocharged SP at 110 horsepower (six more horsepower than a 916, and that’s without turning the boost way up), Lee got the go he was looking for.

Mike Lee's Turbocharged Ducati 900 SP
With the tank strapped in place, only the pipe gives away the appearance of a stock 900 SP. Lee worked hard to make the kit fit easily on a stock bike in order to retain the classic lines of the Ducati, and it paid off.Photography by Tim Tew

The foundation for the turbo unit is a small IHI, blow-through system (the cfm is proprietary, though any turbo expert could look at it and determine which model it is). The beauty of the unit is that, thanks to Lee’s preparation, it bolts onto the 900 with a minimal amount of fuss using the stock carburetor. All the hoses and fittings are already mated, so the customer doesn’t have to worry about submersing himself in a three-day project.

With the package comes several modifications for the stock 38mm Mikuni CV carburetors, including a Factory needle built specifically for Lee’s effort and a different pilot and main jet (the stock slide and slide spring are retained).

Mike Lee's Turbocharged Ducati 900 SP's header system and collector
A more complete look at the full header system and collector shows the outstanding workmanship involved. Jim Higgs of JB Racing puts 24 man-hours into creating each system, and has been working on IMSA and IndyCars for years. A stock 900 full fairing will fit over the header, but who’d want to hide it?Photography by Tim Tew

Lee deduced that there was too much downtime between the twin’s power strokes to keep air pressure constant enough for use with the turbo, so an airbox top that receives filtered air from the turbo unit comes with the kit, fully pressurizing the airbox and carburetor. “The unit would work without the airbox modification,” Lee told us, “but I basically use the airbox to store pressurized air. In a twin, you need 3.5 times the cylinder volume of stored air.”

To ensure proper fuel metering, a self-adjusting fuel-pressure regulator also comes with the kit. If fuel pressure does not remain above the air pressure in the float bowl, the mixture will actually be blown back out the main jet. The regulator automatically adjusts itself to remain two pounds above the manifold pressure at all times. This piece alone costs $500.

Mike Lee's Turbocharged Ducati 900 SP's turbo air filter
Peeking out from beneath the half fairing on the right side is the turbo’s air filter. Lee has already put 3000 turbo miles on the bike without any problems, and doesn’t feel he needs to strengthen the bottom end until he’s making 150 horsepower. Hmm.Photography by Tim Tew

You’ll notice that Lee’s SP wears the half-fairing found on the less expensive CR in order to display the curvaceous, handbuilt stainless exhaust (also available in Jet Hot–coated mild steel). “It costs me $1000 just for the exhaust,” said Lee. “Twenty-four man hours go into making each one.” And it shows.

The one time we were scheduled to ride one of Mike Lee’s turbo bikes in Florida, it was stolen out of the back of his truck. But after further development since then, he couldn’t be happier with the bike. “With just three to four pounds of boost (the kit is sold with a 3- to 5-pound adjustment) the SP pulls second-gear power wheelies,” Lee states. “But it’s not an intimidating kind of power—you really can’t tell there’s a turbo on the bike, it’s so streetable.” We’re currently trying to finagle a turbo Ducati shipment to our offices in Los Angeles, but until then, we’ll have to take Mike’s word for it.

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