What is the movie with a kid, a wiz with inventions, and a "lake monster" that turned out to be a tractor?

Question

On the disney channel in the late 80's to early 90's.

The kid rode his bike on the railroad tracks with special wheel attachments so he could stay on the rail like a train.

When he's diving into the lake to find out whatever it is he freaks out when he see's a face and it turns out to be this white mask or something.

Answer 1

Check “Frog Dreaming/The Quest” http://www.imdb.com/title/tt0091810/