Engine problems forced Kirkby-on-Bain's Steve Plater to retire from round seven of the British Supersport Championships at Oulton Park on Sunday.
Plater was going for a third successive podium finish on the AIM Yamaha but ended his race after lap three, complaining his bike was losing power.
He admitted: "I have no idea what caused it to slow, it will be stripped down next week to solve the problem."
Ruskington's Rob Frost came home eighth in the race on the Buff Racing Triumph.
In Superbikes Cal Crutchlow of Louth-based HM Plant Honda claimed sixth and second-place finishes, with team-mate Leon Haslam picking up a brace of fourth places.
Suzuki's Tom Sykes won both races, his first victories in BSB, while series leader Shane Byrne twice came third to extend his lead over second-placed Crutchlow in the standings by two points to 99.
Lincoln's Lee Jackson picked up a podium finish with third place in the first of the weekend's superstock races on Saturday, following it up with fourth in race two.
Alford's Peter Hickman came home fifth and eighth, with Ben Wilson from Boston finishing 11th and seventh.
Wilson also took second place in the R1 Cup race, dedicating his podium finish to his former team-mate Ollie Bridewell on the first anniversary of his death in a crash at Mallory Park.
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