rectifier heats up

the rectifier on my 77 kz1000 is hot to the touch after running for several minutes .Is this normal ?

If everything else is working fine, then yes. Unless you left some skin on it in which case it's a bit TOO hot.

The diodes in the rectifier will generate some heat, so it's normal for the block to be a bit warm, especially if it is warm outside.

gogo123 wrote: the rectifier on my 77 kz1000 is hot to the touch after running for several minutes .Is this normal ?

Does your bike have a reg-rec combo unit?
Stock, the 77 KZ1000 rectifier unit & voltage regulator are separate parts.
I would clean up all of the connections & do the charging system checks.
And make sure the battery is good by testing it.