here we go again

Cracked/leaking carb inlet rubbers?
Get the engine running and spray the rubbers with 'Easystart' or similar (some would advocate the use of WD40). If the revs pick up then you have perished rubbers.
Which bike is it? Not that it really matters ... if it's on carbs then they are all similar.

 

The only other thing that comes readily to mind is dirt in the carbs or fuel filters if fitted. May be worth a look. Could even be muck in the bottom of the petrol tank. My Trident often has lengthy periods of idleness due to health issues, both me and t'wife, so I try to make sure that there is always a liberal dose of Redex , or similar, in the petrol to keep carbs etc clean. Seems to have worked so far!
And yes, I am now clutching at straws!!

 

any chance you can type it out so it makes sense,lol?

steve, I am the same as you and use additives,have to say it seems to work

 

Had a similar problem with my 07 T 100.
Found that the O ring gaskets either side of the
Inlet insulator missing. Fitted new ones,now runs fine.

La Roca

 

I had an 04 T100 which ran much smoother after syncing the carbs. Also have you tried cleaning out the little filter which sits in the T - piece at the end of the fuel inlet pipe? Can collect a lot of muck in 11 years!

 

I bought new inlet rubbers from Sprint, Less than a year later, and they were perished to the point of cracking on the outside. Obviously shit Chinese materials.