OK - I think I found the answer. If I'm reading the article correctly, it is 1 link of chain per 2 new teeth on sprockets. Here it is from Z1E:
Changing sprocket sizes may effect chain length. As roughly 1/2 of each sprocket has chain touching it, each tooth added to stock sizes will require approximately 1/2 link of additional chain. Increasing total teeth by one or two teeth can usually be accommodated by moving the rear axle forward slightly and keeping the stock chain length - but if you start changing sprocket sizes more than one or two teeth, you will need to increase chain length. Going up four teeth will require a chain 2 links longer.
The Kaw List:
Current: 79 KZ1000 A3 MKII, 78 KZ1000 A2, 78 KZ1000 Z1-R, 78 KZ650 SR, 80 KE175
Former: 03 KLX400SR, 99 ZRX1000, 82 KZ750 LTD, 80 KZ1000 A4 MKII, 80 KZ1000 LTD, 78 KZ1000 A2, 74 H-2 750 Triple, 78 KL250
