Can i delete part of the mesh without losing my weight painting?

Silverland

 I have finished my weight painting of the whole characters head and mouth tongue and teeths and started to do shoulders. Thats where i realised that its very hard because i have body underneath my tshirt and shorts so i decided to delete this body. The problem is that after deleting it i lose all the weight painting. Is there any chance i can still preserve weight painting where it is after deleting underneath body parts? If not then i also thinking about giving underneath parts of the body transparent material but dont know yet if it will not produce rendering issues?

fatihG_

Duplicate your mesh.
On this duplicate, make your edits.
Bind this new mesh to the same skeleton.
Transfer weights from old to new mesh.

If there are any random verteces that cause spikes and what not, use the hammer skin tool.

Silverland

As I expected it didn't work for me. Please help me because I really want to learn this process. 

Here is the video of me following step by step your advise -

https://www.youtube.com/watch?v=MoV1-K7ccKk&feature=youtu.be

And here is my Maya file with new unskinned body (Body2) and old skinned body (Body1). 

https://drive.google.com/open?id=14GcUKgUgu8U-7r9uBLS1PJGJmKp7-6JmJm

What is going wrong here?  Thanks in advance

Silverland

This link works - https://drive.google.com/open?id=14GcUKgUgu8U-7r9uBLS1PJGJmKp7-6Jm

fatihG_

I notice when you selected your skeleton, none of the joints in the skin was selected. (they were all magenta, not that teal/green 'selected' colour.)