McAMS Yamaha's Jason O'Halloran swapped the frame on his version of the Bennetts British Superbike R1 after it became very aggressive to ride and immediately shot to the top of the Portimao test timesheets.

The Australian and his team had changed components including swingarms and suspension links to try and resolve the problem but after a ride on team-mate Taz Mackenzie's bike, it was clear where the problem was.

"It was exactly what we needed. We had a difficult couple of days. We had a difficult end to Monteblanco even though we were fast, we had a few issues with the bike. We changed the frame there and ever since it has been really aggressive," said O'Halloran, speaking at the track.

We persevered with it here, we thought it was the swingarm, the link, then I went out on Taz's bike after lunch and his was completely different.

"The boys changed the frame for me, I sat out for a couple of hours, but I immediately knew it was different. We did a run on old tyres and I managed to do my best time on tyres that had done 16 laps.

"So we put a new set in and got up the front so I'm looking forward to Silverstone and being at the sharp end."