The "dry" clutch is the most personal part of a speedway bike to a rider. Some riders prefer it to "bang" which makes the bike jump from the start and then they will feather the clutch several times before the first bend. The front wheel will hover all the way to the first bend.
Other riders prefer it "soft" which entails a different technique of controlling the bike.
Every speedway rider spends hours and hours of time and money on his clutch!