Lets say I have two flybars, a ong and a short one and I have two sets of weights.
If I am using the shot one and I use the heavy ones how will if react and then if I change to the lighter ones what will happen ?
And same question for the long flybar. jUST THE FACT PLEASE no guess work please Thanks for the help.

I can handle this question.
There are a lot of variables with flybars. What you are messing with is the spinning weight of the rascal.
A light / long will have similar control to a heavy / short flybar.
The longer the fly bar, the less it needs to weigh.
In theory, if it gets long enough, you don't need any weights at all.

I made a fully functional flybar by cutting the loop off the end of the flybar. Then I glued a length of CF rod onto the metal flybar rod. The CF rod was about 3 3/4" long. Then I layer shrink sleeve over the CF rod until I had a flybar that weighted about the same as the stock one. I did make sure the flybar was balanced - It had to spin true. It was really durable and had no weights at all. Pretty cool.

To answer your question, try it! I know what you'll find, but that's no fun.

OK, here's the poop. Use either flybar. They both need weight. The long one needs less than the short one. If you start removing flybar weight the helicopter will become more agile and will loose stability at hover. If you want to hover, that's bad. If you want to fly, that's a good thing. A really good hover helicopter will be hard to fly. An agile helicopter will be hard to hover.
A 195 gram helicopter can be a real trip because it doesn't have much mass. It can get really quick.
The more weight you remove the more agile the helicopter will become.
The more weight you remove the more difficult to fly the helicopter will become.
At the extreme, the helicopter will react so quickly that it will be nearly impossible to fly. I do wonder if a good single rotor flier could fly a coaxial with minimal flybar weight. I suspect that it moves so quickly that a flier can't keep up with it. To fly a helicopter you need to be predictive. You need to know what the helicopter is going to do just before it does it. The coaxials with no flybar weight are like squirrels on crack. I can't predict what it's going to do next with no flybar weight.

If you have a stock flybar, remove the brass weight but leave the boot. Fly. Do you like it? Great, go be happy. To make my point, remove the brass weights and the rubber boots. Try to fly. How's that working out for you? That's why I use a single collar on the wire flybar with no boot.

Does that add anything to your knowledge base?
Soloboss

Thank you so much for the great info Soloboss. I will try what you have tought me. Thank you.