The American again qualified 19th and last for Sunday's Portuguese GP, then retired after just two laps with a slipping clutch.

"The clutch failed. I don't know why - it wasn't from the extra horsepower we put in it!" joked team principal Kenny Roberts Sr. "I guess he burned the clutch up too much coming off the line, and it never recovered. It wasn't going to be a very good day, no matter what, but we would have got points. We need some help for acceleration, otherwise it's kind of a waste of time."

All Honda's satellite teams complained about engine performance at the start of the season but, after 14 of 18 races, Team Roberts is the only team not to have benefited from engine upgrades from HRC.

"There was a rumour that Honda will have some more horsepower for us at the next race, and I hope it's true, because this is starting to get ridiculous," fumed Kurtis. "It's frustrating when you are the only guy that hasn't had the engine update yet. I've tried to be positive all year, up until now - but it's getting stupid. I don't think anyone would want to ride the thing like it is now. You can't draft anybody, you can't accelerate with anybody, you can't shut anybody off to pass them properly. Hopefully it'll get better for Japan."

Kurtis' older brother Kenny came within one lap of winning the 2006 Portuguese Grand Prix, using the competitive 990cc version of the KRV.