Suzuki GSV-R990

As the Rizla Suzuki MotoGP mechanic warms up the GSV-R990 belonging to rider Chris Vermeulen just outside the pit garage at the Valencia circuit in Spain, I stand ready and waiting, thinking about my experience with the bike in '05 at this same racetrack. I am first on the long list of journalists to ride Suzuki's Grand Prix machine this time, and all I can think about is how it seemed that the bike was neutered when I rode it the year before. The '05 machine belonging to John Hopkins just had felt a little flat compared with the Ducati Desmosedici I had ridden the previous day back in November of that same year and the Suzuki MotoGP GSV-R test-team bike I rode in '04. I can't help wondering if the Suzuki team is going to give me the same ultrasoft engine mapping this time around as well.

Suzuki GSV-R990

Suzuki GSV-R990 side view

It's pretty easy to see that the GSV-R keeps its mass fairly low and centralized.

The Rizla Suzuki mechanic motions that everything is ready, so I shut my helmet shield and climb aboard, very conscious of the fact that Vermeulen rides with a conventional shift pattern (one down for first gear and five up for the rest of the gearbox ratios) rather than the reversed race pattern (one up, five down) used for most racing machines. A mistaken backshift on this racebike would obviously be disastrous, for my physical well-being as well as the GSV-R's.

I head down pit lane making sure my leathers are comfortable and positioned correctly, and as I head out onto the racetrack after checking to ensure no one is on a flying lap behind me, I hope and pray that I got the "full monty" engine mapping this time.

There's not a whole lot of electronic tirckery in the cockpit of the Suzuki GSV-R990

Going Pneumatic
The biggest changes in '06 to the Suzuki GSV-R990's all-new engine were the move to a wider 75-degree angle in the V-4 powerplant and the switch to pneumatic valve springs. Now commonplace in Formula One auto racing engines, a pneumatic valve spring replaces a conventional metal coil spring with what basically amounts to a miniature piston and cylinder in its place. By highly pressurizing the cylinder with a gas (usually nitrogen, due to its temperature-inert qualities), an "air spring" is created with numerous advantages over a coil spring. The biggest benefits are that reciprocating weight and internal friction losses are substantially reduced (no springs and retainers mean less moving parts, and air-spring pressure remains fairly constant for the initial movement, meaning that ultrastiff springs-which create friction-are unnecessary to ward off valve float). And valve float itself (where the valve follower fails to maintain contact with the camshaft at high rpm) with aggressive cams is basically eliminated. The downsides are some additional weight and complexity due to the need for a pressure storage tank and the various regulators and pneumatic hard lines.

"We had a lot of trouble [in '05] and the year before with valve-spring reliability," recalls Kunio Arase, project leader for the GSV-R. "At high rpm, the harmonics created in the valve springs were causing metal fatigue that resulted in several failures," so Suzuki developed the latest GSV-R990 with a pneumatic valve train. "This allowed us to easily raise the maximum rpm level with the new engine 1000 rpm higher, without so much concern for reliability." What about maintenance, since the system's high pressure is crucial to its performance? "Maintenance has been very easy," he continues. "We only have to perform basic maintenance every two or so races, whereas before it was after every race."

It's notable that the latest GSV-R800 uses a pneumatic valve train as well (and to apparently good effect-both Rizla Suzuki MotoGP riders John Hopkins and Vermeulen have been at or near the top of the time charts at the first two preseason tests of the '07 season). Was this a sort of trial run for the 800's pneumatic valve system? "Yes," reveals Arase, "although it had been developed and tested prior to using it on the 990 this season. The system used on the 800 is not much different than the one used on the 990."

The all-new 75 degree V-4 engine required an all-new frame to house it.

The use of pneumatics in the valve train enabled Suzuki engineers to fit slightly more aggressive cams, although it's not just a simple matter of slipping in racier cams and getting more power. A lot of R&D time was spent massaging the power delivery so that the extra power wasn't more of a hindrance than a help. "We changed power delivery through refining engine management," says Arase, "paying special attention to engine-torque character, to make it easier for the rider to accelerate out of the turn. The technical application here was very difficult, but we were able to manage it properly after some refinement."

Arase is naturally very coy about revealing any peak power figures, saying only that the GSV-R990 has "over 240 horsepower." Bore and stroke, as well as crankshaft firing order, were supposedly unchanged from the '05 model.

What about using traction control to smooth out the power delivery on corner exit? "Our traction control has been refined quite a bit," answers Arase, "but we still have a lot of room to improve in this area. Wheelie control has also been developed, but we only use it at circuits where wheelies are a problem." Although Hopkins had informed me in '05 that the team would be using Magneti Marelli engine management for the next season, apparently that didn't happen. The GSV-R's engine-management system appeared to be a more advanced version of the same Mitsubishi EMS of '05, not the Marelli system as used by most of Suzuki's competitors.