Hard Idle

I have a 1982 KZ750 and it has a very hard time starting. It will start, but it usually needs a jump. I'm going to have the battery tested tomorrow (no shops open on Sunday here in Utah), are there any other electricals I should check out? I had a similar problem on my VW, and a new battery fixed it right away.

The problem after it starts, however, is it has a very rough idle. It needs several minutes to warm up and start to run correctly. Good news though is that when it warms up, it runs like a tank. I've considered a carb rebuild along with new jetting, but maybe they just need to be resynced?

Hi, You'll probably find a resynch will help.
To be absolutely sure check everything over - valve clearances, good spark, timing etc...
A strip and clean of the carbs is always an idea and there are plenty examples of peoples methods for doing this on here.
If you can't remember the last time they were cleaned - clean them.
You really only need to think about rejetting after all of the above has been done and you have medded the bike with another pipe, pods or pistons for example.

start with a new fully charged battery, the bike wont run right, if its not putting out the right amount of volts, if that does'nt fix it do as Dave suggests

if that happened to me I would want to choke the thing.