KR V5 race debut this Sunday.

After an impressive first outing at the French GP, followed by a full day of successful testing, the all-new V5 four-stroke Proton KR racer is scheduled to make a full racing debut at this weekend's Italian GP at Mugello.

Riders Jeremy McWilliams and Nobuatsu Aoki both plan to race the newest four stroke on the block at the classic Italian circuit - part of the bold public development programme of the noisy new racer after its first time at a circuit only two weeks before.

"I'll miss everything about the old bike... except the lack of power, and having people passing me so fast on the straights it's frightening," admitted McWilliams. "Ive really been enjoying the new four-stroke, even though there's obviously still a lot of work to be done. It's really compact and comfortable for me, and a pleasure to ride - so easy after the two-stroke.

"The bike has so much power that if you touch the throttle when it's cranked over the wheel can't help but spin, and then you control the slide with the throttle," added the Ulsterman. "It may not be the best way for lap times, but it's a lot of fun. It might be possible to get a better result at Mugello with the two-stroke, but we need to work on this bike for the future."

The machines have already accumulated more than 100 laps at the French GP circuit over the weekend and on the Monday test, without running into any of the teething problems that had been tackled step by step during bench testing. This was four times race distance, and a landmark as the inevitable early difficulties are overcome.

"We had a few little hiccups, but nothing serious," said team manager Chuck Aksland. "The engines held together the whole time, and we were able to make a good start at improving our base settings and getting some track miles done to build up data on the new machine."

The radical new 990cc four-stroke, which exploits a compact and original V5 engine design to make a notably small and agile machine, had never even been round a corner before the first tentative laps in the first untimed practice session at Le Mans.

One day later, McWilliams confidently set tenth-fastest time on a wet track; three days later both riders were achieving comfortable qualifying lap times. The proof of the overall balance of the package came in that both are already asking for more power. That situation will not change for this weekend's GP.

"The bike's not running to its potential yet, and unfortunately there's not much time to do anything about it. As I said at Le Mans, it'll be three months before we're ready to do battle," said team owner Kenny Roberts, himself triple World Champion and a racing legend. Roberts himself took a hand in early development runs on the new machine.

"It's not going to be a rocket ship at Mugello, and it's not going to handle as well as we'd like," continued Roberts, now firmly established as the leading independent racing manufacturer by the arrival of the new bike.

"We don't have enough parts for that yet. Le Mans was basically a shakedown tests, and the good news is that the engines held together," added the American. "We're letting everybody see what we're doing in the early stages of development. We could be wrong in our direction, but I think it's interesting for people to see," he continued.

"We have a very broad power band at the moment, and our first target will be to take some of the mid-range power and move it higher up the rev range."

While the race team continues race-testing, still establishing base settings for chassis and the all-important slipper clutch system, engine development work is continuing at Banbury and in the USA, where Rob Muzzy is dyno-testing to develop the next stage of tuning parts.

The promise of the bike is already clear, however, after the thunderous exhaust claimed everybody's attention at the Le Mans fire-up.

The new Proton KR may not yet be the fastest bike on the grid, but it's the youngest, some already think it the prettiest... and definitely the loudest instrument in the MotoGP class's exciting exhaust-pipe orchestra.

The Mugello circuit includes one of the fastest straights of the year, where the 990cc four-strokes are guaranteed to top 200mph.

This is just one challenge faced by the all-new GP machines. Others include the likelihood of very hot conditions, not to mention a 20-plus field of race-developed rivals.

"We expect to have three of the new machines in Italy - one for each rider, and one spare," confirmed Aksland. Finishing the race is the primary target, and will be a significant achievement for the first prototypes of the new machine.

The last word goes to Roberts: "We know we need a lot more development. But this bike is just the match we're using to light the fire."

The Italian GP is the fifth of 16 World Championship rounds, with the Catalunyan GP one week later as the European season picks up the pace.