I'm guessing your have a size 428 drive chain. The pitch of a size 428 chain is 1/2-inch.
You might enjoy visiting the following link.
http://gizmology.net/sprockets.htm
Make sure you order a chain long enough to fit your new, larger sprocket.
How long is the current drive chain, and what are the sizes of the current sprockets? Also, what is the size of the larger sprocket you want to install?
Spud
__________________
Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894