TOPIC:

Is there a way to repair an old float needle valve on a 78 kz650 so that it will stop leaking? If not, does anyone know where a repair kit can be purchased?

hmmm...repairing a needle valve...You can clean them up,if the ridge isn't too bad...some fine sandpaper(800 grit)or some scotchbrite.
Be sure to sand it from the tip,up along the base,and not around the taper,and turning it as You sand.
I've been lucky before,and depending on how much of a ridge is there,You might get lucky too.

www.siriusconinc.com/carb/parts.asp
got to this website they say the one you need is sold out right now but it's just $17 - i'm guessing it includes new needles. on somthing cheap like that i don't jack with it, just replace it and avoid a headache

You could try Parts N More website I see they have your carb kit & float valve. They have free shipping but you have to have a $35 dollar minimum order. I have not personally ordered from this site so I have no idea how there customer service is.

www.partsnmore.com/cat_index.php?model=kz650&category=carb

Check Z1 Enterprises for a carb rebuild kit.

If all of the above fail you could try cyclewareables.
www.cyclewareables.com/pages/carb_needle...s/carbsearneedle.htm
I got float needle here a few years back with no problems.

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Woodstock ON Canada
1980kz750E1, 4->1, K&N pods