Used- Kawasaki 1976-1977 KZ900 Starter, P/N# 21163-004, Good Condition, (see photos), Sold AS is, No Warranty, No Returns on electrical parts, Be sure before you click "buy it now".
“Please do your own independent research to ensure this part will fit your explicit needs. Specific models provided in title and description are for reference only and may be incomplete or incompatible for your intended usage.”
This is what I found on Partzilla for fitment:
Kawasaki
1977
KZ900/Z1
1976
KZ900 LTD
KZ900/Z1