Britain's Cal Crutchlow has expressed huge concern over the speed of his Monster Yamaha during today's Motorland Aragon MotoGP round, especially given he was on a brand new engine for the encounter.

The Isle of Man resident said there is a big conspiracy theory in his garage as to why he was slower than team-mate Bradley Smith in terms of average speed and had the slowest average speed of the prototype machines, bar debutant Yonny Hernandez, in the race.

"I had no straight-line speed. There is a big conspiracy theory in my side of the garage as to why we have a brand new engine this morning and it's no faster than a 2000km engine or whatever we are allowed to do," said Crutchlow, speaking at Aragon.

"If you look at this morning's warm-up, average speed I was 13kph down on the top Honda and nine kph down on Valentino and seven down on Bradley. I don't get it, this is not five kilogrammes of me, weight-wise. We know the factory team has the seamless shift, which helps a little, but it doesn't explain why we are so down compared to Bradley.

"I lost a podium position, I believe, through the speed of the bike and it's not going to get any better as we are going to Sepang and Motegi in the next two races. Don't get me wrong, the Yamaha has never been as fast as the Honda, but we can't even hold the slipstream.

"I had a slipstream every single lap of the race and I am still, on average, the worst prototype. Bradley rode round on his own for the whole race and his average was better than ours. I don't get it, our team don't get it. The bike is slow, simple as that. We can't explain it.

"This morning, I was gaining two tenths on Lorenzo under braking and round the last corner so imagine how much we are losing in a straight line. We worked out that over the lap we are losing four-tenths on all accelerations and straightlines. It's not acceptable. We were fine with fuel this weekend, so that has nothing to do with it.

"We had a brand new engine which normally gives you more speed and it was the same as the old engine. I am not happy at all with regards to that. You can't ride round busting your sacs every week to compete and be so far off due to lack of machinery."