Newbie here and got a KZ750 for $500.
The bike was running for about an hour, then I pulled over and shut the bike off. It would not start. I pushed the bike back, and jumped the bike with a car. After running for a min, the bike rpm will lower slowly. The RPM will slowly drop and die when it is idliing. After a few times cranking the bike, the battery dies.

The second problem is the carb. nipple on the bottom is leaking. How do you fix that?

Any info will be great.

 

Leaky nipples!??? Sounds kinda personal. Sorry, had to.

The nipples are dripping fuel because either the floats are not set properly, they're sticking, or you have worn out float needles.

As for it dying, you should first check the charging volts while it's running. Make sure there is a minimum of at least 13 volts. (That's a very low minimum...) 14.5 volts is normal. If the charging system checks out. your carbs may be flooding the engine due to the reason I stated above about the floats/needles. You also should get a new battery if you have decent alternator charge.