chain legnth

i am currently waiting for the return of my stock swingarm from my 1976 kz 900. it is being cut and extended 6 ". does anyone have any idea how long the chain will need to be afterwards?

Depends on the chain. If it's a 630, each link is 6/8ths (or 3/4th) of an inch long. If it's a 530, each link is 5/8ths of an inch long. Since you extended your swingarm 6", your chain needs to be roughly 12" longer. So, for a 630, 16 links longer, for a 530, 19.2 links longer. Since chains come in piared links, either 18 or 20, depending on where your chain adjuster settles in.