I can't get these weight to work. Can someone help.

I create a copy of a blueprint, into the mod folder, change the weight, changed the game data for it and it changes the weight, but crashes within 3-5 mins.

This is a very vague post, please be more specific.

What blueprint are you trying to modify?
What do you mean by ‘weight’?
Does your editor crash or is the crash in-game?