Yamaha Welkom MotoGP set-up report.

In the 2001 race at Welkom, South Africa, Shinya Nakano (Gauloises Yamaha Tech 3) continued to impress the MotoGP 500 World Championship paddock in his second outing aboard the YZR500 with a sensational fourth place. Starting from the front row for his second consecutive Grand Prix he survived a race long battle to collect enough points for equal third in the championship points standings. Not a bad result for a MotoGP Rookie. Closely following the Japanese at the time was fellow countryman Norick Abe (Antena 3 Yamaha d'Antin), who eventually finished fifth after leading the 28-lap race in the opening stages.

It was a battle the Red Bull Yamaha WCM pair didn't survive when Garry McCoy and his former teammate, Noriyuki Haga, both crashed out. The Aussie was hoping to prevent eventual race winner Valentino Rossi (Honda), Loris Capirossi (Honda, 2nd) and Tohru Ukawa (Honda, 3rd) from making a break on the field when he charged in too hard under Kenny Roberts (Suzuki, 7th) - his over enthusiasm ended any chance of a repeat of his 2000 winning result.

After a poor start Max Biaggi (Marlboro Yamaha Team) put together a performance that saw him move up through the field. He found himself 14th after the first lap when a rider nearly crashed in front of him, but recovered to eventually finish eighth. This year Biaggi and his Spanish teammate Carlos Checa intend on doing much better on the YZR-M1.

Checa's spectacular podium performance during the 2002 Suzuka MotoGP, held April 7, showed the potential of the Marlboro Yamaha Team four-stroke YZR-M1. Yet Yamaha acknowledges that there is still work to be done if the M1 is to stay competitive in such a demanding championship.

The Spaniard's third place, in Japan, was the result of the latest evolution of the YZR-M1 Deltabox chassis, which offers increased feel on the front-end and improved overall balance during the initial turn-in. The key difference is down to the engine mounting position and a new direction in chassis geometry set-up.

Now less aggressive than the YZR500 in set-up - with the rake gradually increasing and the rear ride-height decreasing - it is in this direction that Yamaha engineers will continue the chassis development during the South African MotoGP, due to be held on April 21. These changes, which normally should have a counter effect, have resulted in a further improvement with the bike's turn-in, increased front-end feedback while still continuing to provide the rider with stability under brakes.

The latter will be improved further by reducing the amount of forward pitching that the bike experiences during deceleration, which will in turn reduce the load on the front tyre, improving feel and the rider's confidence to brake deeper. A combination of reducing the M1's rear ride-height and increasing the front fork preload/spring rate, to prevent the bike falling through the front fork's stroke, will achieve this. Although Welkom isn't a circuit notorious for heavy braking, these changes will still prove beneficial on the slippery layout, especially when the rider is attempting a passing move.

Due to circuit's high elevation, power loss is a major issue for all concerned - both two-stroke and four-stroke. The less dense air will see all motorcycles down on power by nearly 15 percent. In an attempt to reduce the effects Yamaha technicians will sacrifice a little low rpm drive to chase a stronger top-end and midrange power delivery. There are a number of steps that can be taken to achieve this on a four-stroke, including revised cams, lighter pistons, different exhaust specifications and reduced internal friction.

As McCoy discovered in 2000, what the 16.5 inch rear tyre offers - over what was the more popular 17.0 inch rears at the time - is an increase in side grip, greater predictability, and improved endurance. Combined with the low grip levels available from the Welkom surface, even in ideal temperatures, 16.5 inch rubber will prove to be a key player, again, as it was last year.

Contributing to the low grip levels are the barren Welkom surroundings, which, when combined with strong winds can lead to a film of grit covering the track surface. It makes finding the perfect race day set-up difficult for competitors, with the track conditions constantly changing. As the weekend progresses the circuit tends to offer more grip, the lap times fall, resulting in an endless cycle of chasing chassis settings to suit the increasing speed.

With drive such a key issue, softer suspension settings are the most likely scenario, although the four-strokes may need to be firmed up somewhat in comparison, due to their heavier weigh limits. A lower rate rear spring will be used to improve rear wheel traction and predictability, while the front will be set to balance out the package.

Since most Welkom corners are medium to high speed, with very little in the way of seriously hard breaking areas, this softer chassis setting becomes a compromise between chasing drive and handling. It can, therefore, result in a certain amount of under-steer while under power. With the weight transferring to the rear of the motorcycle it can cause the rear to squat, unload the front, in turn affecting the bike's geometry. Raising the rear ride-height will reduce this to some degree, but it's for this very reason rear wheel steering can produce such strong results at this circuit.