Brimbank Divisional Response Unit detectives are appealing for information following an aggravated carjacking in Cobblebank on Sunday.
Investigators have been told the victim agreed to meet with a man, who were interested in buying his motorcycle, after he posted an add to social media.
The victim met up with the male at a carpark off Stadium Drive in Cobblebank before a second male appeared and threatened him with a knife on 18 May about 1.10pm.
After making threats, both offenders fled the scene, one riding the stolen KTM and the other on a black and white scooter. Both offenders were not wearing helmets.
The distinctive motorcycle, a KTM 500XC, has back and white decals, road tyres, a loud exhaust and registration number of 2S7XM.
It was last seen in the vicinity of Brooklyn and Clarkes roads in Brookfield.
Detectives are appealing for witnesses who were in the vicinity of Brooklyn and Clarkes roads, to come forward, as it's believed the pair were riding in the area just prior to the incident and after they left the scene.
The first teenager is described as approximately 170cm tall, Caucasian in appearance, about 16-18-years-old, with a medium build. He was last seen wearing a black hoodie and pants.
The second teen is described as Caucasian, about 180cm tall with a slim build. He was wearing a white shirt with print on the front, black pants and a balaclava.
Investigators have released an image of the stolen motorcycle in the hope it assists the investigation.
The 26-year-old victim wasn't physically injured.
Anyone who witnessed the incident or with dashcam or CCTV footage, is urged to contact Crime Stoppers on 1800 333 000 or visit www.crimestoppersvic.com.au.
