What to add to the kz900 to get that extra umph?

Like 650 Ed, & Dessert KZ , said, just get it properly running in STOCK form, & it will be turn key ready to ride every day, once you stat making upgrades, you'll be wrenching as much as riding & you'll be taking away the value of a completely Stock 40 yr. old bike
Pete

I think there are many of us with mild cams and a 1075 with no reliability problems. I love my motor with the 1075 bore, 29's, mild cam and updated ignition. I ride the snot out of it and knock on wood have had zero problems. It does take some wrenching to get there but if you do it right it be a ton of fun.
Wayne

1976KZ900 I'm in a similar situation to you. My '76 KZ900 runs well but it's not that impressive. Compression is low on a couple of cylinders.
I am going the econo route, bought a used set of KZ1000 pistons, bought new rings and had a spare cylinder block bored to 1015cc. All that cost about $350.

I'll get it installed sometime this year, after I finish my H1 project bike.

Throw a baby bottle full of nitrous under the seat and hang on! :woohoo: