Rossi overwhelmingly clinched the world title on his Repsol Honda this season ahead of fellow Italian Max Biaggi.

But next season World Superbike stars Troy Bayliss and Colin Edwards are making the switch to MotoGP, while rivals Ducati will make their debut in the sport.

And Rossi said: "Honda have some plans for a six-cylinder but for me that's not right. Honda making a six-cylinder is crazy.

"The engine is not the problem, it is traction. To make the bike better, we need a better chassis."

Rossi has already notched up back-to-back world titles but faces a battle in 2003.

The Italian rider was one of the few to have a four-stroke bike at his disposal for much of the season.

And he admitted: "Next year it will be more difficult.

"There will be eight Hondas, all four-stroke and we basically have all the best riders in the world in one class."

Rossi is currently in England testing for the Network Q Rally of Great Britain.

He will make his debut in next month's event having been drafted in by Peugeot.