If your asking about silver can 540's,
Start at 2v for 1/2 hour , reoil, then 4v for as long as you can stand it
Keep oiling occaisionally.
The brushes in these motors are very hard and a bit of patience really pays off.
As noobie said
i accidentally left it running for about 2 hours... coz i forgot about it... i ran it in a race a few days later... .. i was racing my mini in the novice 4wd tourer class as there were only 2 mini entrants... i was running down stock tourers in the straight