Sorry to bump an old topic but theres not many topics on this.
Alot of spots are being cracked down on due to the huge population increase and activity in the Fraser valley especially places like Jones Lake but there are tons of Forest service roads all over the place,
If your looking to just ride up a mountain and see how far you can go then I suggest Carolin Mine road up Hwy 5 or BC Nickel Mine road up Hwy 1, they go for quite awhile.