Pata Honda's Jonathan Rea struggled with problems at the Jerez World Superbike test and can't put a finger on where the fault lies but reckons an aggressive engine made it difficult to put in a fast lap at the tight Spanish track.

Although final laptimes haven't been forthcoming, the Irishman was more than a second off the pace of Tom Sykes earlier in the week but says that some new strategies for 2014 will smooth things along.

"After a positive test at Aragon, I really struggled here at Jerez. It’s hard to put a finger on our problems but I feel that the character of our engine is quite aggressive and that makes the lap difficult here," he said.

"We have a few new strategies to implement at our next test in January, which should help. I completed over 200 laps here so now I’m really looking forward to the winter break. I hope to come back in January to make some more progress with the CBR."