Agree with Dickie and the previous post.
However, there is an obvious safety issue as well. Double white lines are usually there for a good reason...restricted vision, possible hidden junction etc. etc
or the good reason as far as we are concerned - Tight bends
Personally - I dont think I'd be considering going between a car and a white line, the driver wont be expecting it and if any on coming car/vehicle is off line the consequences for a motorcyclist could be severe.
Ride safe (but fast
) Frank