Okay I sprayed the carb cleaner everywhere in the carb area and revs don't change

Well, I'm suspecting the carb is simply jetted too lean then if everything else is checking out.
 
As you have several spare carbs, I'd remove the main jet from one to "open up".
E-Bay has jet drill bits for pretty cheap and you'll also need the handle end to hold the bit.
 
They ARE VERY SMALL and fragile.  Once you have your new tools, slide the main jet over the bit
that fits best.  Then, go up one or two sizes with the drill bits.  Slow and steady and the drill will
open the jet...  
 
Put the jet back in, re-assemble and see how the engine behaves..  It may need further drilling..
 
Please post back how it goes...
 
.
 
 

SRTsFZ6
Well, I'm suspecting the carb is simply jetted too lean then if everything else is checking out.
 
As you have several spare carbs, I'd remove the main jet from one to "open up".
E-Bay has jet drill bits for pretty cheap and you'll also need the handle end to hold the bit.
 
They ARE VERY SMALL and fragile.  Once you have your new tools, slide the main jet over the bit
that fits best.  Then, go up one or two sizes with the drill bits.  Slow and steady and the drill will
open the jet...  
 
Put the jet back in, re-assemble and see how the engine behaves..  It may need further drilling..
 
Please post back how it goes...
 
.
 
 

Do I really need to do that? If that's the case why others don't have to drill the main jet? 

You don't have to do anything..
 
With what you've posted, that's how I would proceed. 
 
I will note that some machines, as they age, they require slightly more fuel
as the EPA has them set on the lean side.  A new carb is no different..
 
If un-comfortable with it, let a competent shop look at it..
 
.