Reed issues, any advice?

[soundbeltfarm]

I got a V force reed for my kids ktm sx 65 and it is second hand but out of the same model bike.
I put it in and the bike just wont idle , as soon as it comes off revs it just wants to die,
I put gasket on to stop any leaks .
i took it out and put old reeds back in and the only other thing i done was strip carb down and cleaned the bejesus out of it . re assembled everythiing with old reeds and it went a million bucks .
i will try the v force again but any ideas on what the problem could be?
maybe shit in the carb from when i first put v force in? or air? jetting?
Thanks

[scott411]

check to see the v force reeds are sealing, they do this when they do not seal

[scott411]

check to see the v force reeds are sealing, they do this when they do not seal