Crankshaft weights?

[geoffinbc]

Sounds like your friend is describing a balance shaft(s) You can remove or disable them in any engine that has them so long as they don't drive anything that may be important. They do not actually remove any orderly vibration from the engine they only mask it so the driver does not feel it. They do take a little power to turn and some 4 cylinder engines have two counter rotating shafts so disabling them may be noticeable.