Hi from Massachusetts! Buying my first KZ today.

Just joined up - buying a 1978 KZ650 today, roughly 40k on it, barn find. Apparently it starts (sometimes)!

Wish me luck, I will be back with more details!

Hmmm... so the tank on this thing is a rustbucket. Any advice on a replacement?

Welcome.
You can try ebay, and on some of the different forums for these KZs.
Sometimes rusted tanks can be salvage.
There should be a post here somewhere with different options on cleaning the tank.
Here's one;
kzrider.com/forum/6-paint-a-bodywork/586...out-hopefully#587011

Post up some pictures when you can.

Welcome. Don't get in a hurry. The carbs probably need cleaning before the start up. Very important. You don't want a hole in a piston.

Plenty of info here. Lots of 650 owners.

These old bikes are a labor of love. Which means they will break your heart.

i used por 15 in my tank its about $80 for the kit and seals the tank i havent had an issue with it yet

Thanks for the responses guys, I'm guessing I'm getting into a biiiiiig project here, but I'm excited.

As for that POR15... is that like Kreem? I've heard success and horror stories about sealants. I'm considering a replacement tank or a trip to the radiator shop if this one can't be saved. Remains to be seen, the bike is at my buddies shop at the moment.

To defy the laws of tradition is a crusade only of the brave.

Have fun with your KZ-- I have that exact model I think-- a '78 KZ650B2 (spoke wheels, blue paint job).
Pics:
The Old KZ

The Old KZ

Looks like it, KZ650B - mines a beat up red, will be satin black by the time I'm done with it.

I think the B/B1 models have a round brake fluid reservoir. Mine's a B2, where the reservoir is kind-of trapezoidal.

Then it's a B2 for sure - looks just like your bike but without all the sweet accessories and customizations. Except rust. It has plenty of rust.

So! Reviving this old thread... Finally got the bike, a while later than I thought - hoping to have a running/revived machine by spring.

Here are the issues I'm dealing with:

-Valve cover gasket/endcap leaks
-Regulator/rectifier smoked, needs replacing
-Points are dirty and need adjustment, maybe condenser?
-Speedo cable dead, needs replacing
-Tank rusty on exterior (OK inside, surprisingly)
-Crusty old mismatched mirrors, one cracked
-Surface rust all over the place, not bad, but all over

The whole bike is less than pretty. I'm thinking of recovering whatever chrome I can, then scuffing it with a scotchbrite pad - whatever chrome I can't save goes matte black, along with the tank (once stripped) and the side covers. The seat is... well... unacceptably hideous in my eyes and uncomfortable to boot - whether it ends up being something more saddle-like or a +1 remains to be seen. That's mostly aesthetics but it's how I'd like it.

Now for some questions!

I'm seeing rectifiers on Ebay for about $40... are they any good? Also, I thought the B2 was a different one than earlier models, but these say they're compatible with a ton of generations of Z650s - will they work for my needs? Anybody on here used one?

What other Kawasaki seats are compatible? What other seats/pans from different manufacturers can be jury-rigged with ease? Are there affordable aftermarket options? Anybody make their own, or modify the stock one? Was it hard?

Thanks, all!