Karl Harris - British Superbikes 2005-present

British Superbikes 2005-present

For 2005 he returned to Superbikes with a Honda run from their UK factory in Swindon, finishing 9th overall with a best result of 3rd.

He moved to the main HRC Honda team alongside Ryuichi Kiyonari for 2006, taking a 2nd place at Oulton Park, less than 0.1 seconds behind race winner Gregorio Lavilla. A crash in the first race at Snetterton caused him to miss the second, although he was not seriously injured. He took his first pole position at Oulton Park that year. He came close to his first series win in the second race at Croft in the wet, passed by Leon Haslam with half a lap to go. While Kiyonari won the title, Harris finished fifth overall, behind the semi-works bike of Jonathan Rea, who replaced him in the factory team for 2007.

He switched to the Hydrex Honda team for that year. His best result in the first half of the season was a 6th place, but again he showed good pace at Oulton Park. He scored an emotional second place in the second round at Oulton Park in August.

For 2008 he moved to Rob Mac Racing, riding a factory Yamaha. He crashed in the first round after being struck by Tom Sykes' fallen Rizla Suzuki, leading him to remark that he felt like he'd be hit by Joe Calzaghe. He did not finish any of the first six races of the year, leading him to largely give up on the season. At the final meeting of the season he was quick in practice, before being forced to pull out after his wife sent pictures of him snorting cocaine to boss Rob McElnea. He made a one-off appearance on a works Yamaha in the World Supersport championship at Brands Hatch, crashing out of 5th place.

For 2009 Karl moved to Shaun Muir's Hydrex Bike Devil's Honda team. He was tipped as a dark horse for the title by former rival Leon Haslam, but struggled to meet expectations. Following two second place finishes in round two of the championship at Oulton Park, Harris struggled to compete with the championship contenders throughout the season. On September 4, 2009, with three rounds of the championship remaining, his contract with the Hydrex Honda team was terminated with immediate effect. The team cited poor results as the reason for the decision., having been on a race-by-race deal for much of the season due to Muir being unhappy with his performance He contested the final two rounds on a Sorrymate.com SMT Honda, but crashed heavily in the final meeting at Oulton Park.

For 2010 he did not land a BSB ride, and switched to the British Superstock Championship on a GR Motorsport Aprilia. He left the team after three disappointing races, with the team noting that his "mindset and performance has deteriorated".