I know exactly where you are talking about. This network of trails can be accessed from a number of places including Helicopter Hill (the dirt road at the top of the S curves), private property in the East Canyon development, Three Levels, Horse Canyon, etc.
The Forest Service is aware of the problem with off road vehicles on this network of trails and makes it apart of their Patrol area. The Wrightwood Fire Safety Council has big concerns about potential fire starts in the area. The USFS have been making changes in the area that will make it much harder for off road vehicles to access this area, as there is a big concern as to the potential for fire starting from bikes without spark arrestors, etc.
A lot of time was put into the "Three Levels" area (guardrails and fencing) to make it difficult for this area to be accessed. USFS will soon be installing gates at Helicopter Hill to keep vehicles from entering the area.
Improvements continue to be made to Horse Canyon to keep off road ATVs and bikes out. Of course you can't keep people from accessing this network of trails from their own property, thus we try to make it a regular stop when out on patrol.
BTW, Horse Canyon, which extends to Hwy 2 in the area of the 5,000 ft sign, is under full closure. It is a NO ENTRY closure and is closed to ALL traffic including hikers. While this is indicated at the Hwy 2 side, many access the canyon from the south, from the area you're talking about.
Edited by Wrightwood