Petty connected on 20-of-32 passes with three touchdowns and ran for a score as the Bears (7-0, 4-0 Big 12) matched the best start in school history and won their 11th consecutive game, stretching back to last season.
Lache Seastrunk and Shock Linwood combined for 215 rushing yards and three touchdowns.
Tevin Reese led the Bears' receiving corps with four catches for 110 yards and two scores.
Jake Heaps was held to 7-of-20 through the air for 85 yards and a touchdown for the Jayhawks (2-5, 0-4).
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