i just got a 1989 rm125 from a friend. when i got it, it came with a new magneto in the box. he said it had no spark and he thought it was the magneto or the cdi box. i put the magneto in, set the timing up, and it still has no spark. i did it by the book so i know its right. how do i check the cdi box? and will the cdi box from a 78 rm125 work on it.