On Saturday, police from Strike Force Raptor called off their pursuit of two motorcyclists speeding through Minchinbury.
Shortly before 5pm, police observed the motorcycles travelling at high speed, eastbound along the Great Western Highway.
They chased the motorcyclists and sounded warning devices in an attempt to stop them, but neither rider did so.
Police continued their pursuit, but decided to stop for public safety reasons after the bikes sped through a red light and reached speeds believed to be more than 200km/h.
They were last seen travelling east along the Great Western Highway towards the M7.
Strike Force Raptor would like to speak to anyone who may have seen the motorcycles in that area at that time.
The first was described as a black Harley Davidson and the man riding it was wearing black clothing with white text printed on his top.
The second motorcycle was described as a black, sports-performance model and the man riding it was wearing a blue jacket or jumper and black pants.
Anyone who may have seen the men is asked to contact Crime Stoppers on 1800 333 000.
Raptor was more successful earlier in the day when police stopped a speeding motorcyclist in Cambridge Park about 12.30am.
Police said the bike, travelling west along Victoria Street, reached 119km/h in a 50km/h zone.
They stopped the rider, a 24-year-old member of the Gypsy Jokers, and issued notices for exceeding the speed limit by more than 45km/h and not wearing an approved helmet.
Police suspended his licence for six months and seized his registration plates for three months.