I've been following speedway since 1970, never missed a season despite comets not being about, you can often tell its mechanical by the sound of the bikes, either reving or not getting traction when going round the bends sometimes they sound flat as a pancake, as the saying goes, if a highly tuned bike is slightly off for whatever reason you can often hear it, maybe the rider can't afford or does not want to get the engine serviced / tuned to improve things, so just battles on