Traffic police are investigating a serious motorcycle crash which left a man hospitalised in Waroona on Saturday.
Police said the rider came off his a purple Harley Davidson and hit the bitumen at the intersection of Forrest Highway and Lake Clifton Road about 1:10pm.
Forrest Highway southbound was closed southbound for several hours as paramedics trsted the man and police invistigated the scene.
The RAC Rescue helicopter landed nearby to transport the rider to hospital.
The 36-year-old man was airlifted to Royal Perth Hospital with serious head injuries.
Investigators are urging anyone who may have seen the crash or has any information, to call Crime Stoppers on 1800 333 000 or report online at www.crimestopperswa.com.au
Anyone with dash-cam footage of the Harley before the crash or vision of the incident are asked to upload their files to this police link.