So,I need some advice on rebuilding a 73'Z1 trans...

Well,I have been working on this bike tirelessly for some time now.I finally get her started and cleaned up($700 later)and when you let the clutch out you get a bad,random,knock..But not with the clutch in.

When you go to take off for a ride,it skips? :huh:

Any ideas?And I do have an early kz1000 will trans parts swap?

try adjusting clutch,check nut on countershaft sprocket to make sure it isnt moving under load.could be several things can you tell where noise is coming from?:dry:

Does the knock come from the tranny? (I know, might be a dumb question, but oh well.) Does the rear wheel turn freely in all gears when running?
I am wondering if somehow a gear fork got asswmbled upside down...
Good luck, man. Frustrating but fun as heck to ride!!

When you take off it skips? It slips out of 1st gear? Take off the countershaft cover and check the external shift mechanism detent mechanism; especially the spring. It is located on the upper left of the inner cover and is shaped like a banana. If the detent does't work right, the drum will move and the bike will "skip" out of 1st gear. If the problem REALLY is that the bike jumps out of 2nd, the shift dogs for 2nd or the gears are worn and this is common. If the bike jumps out of other gears randomly, it is possible that the rod that the forks ride on is broken.

I think the tranny from a 78-80 will swap. If you have a good one, remove your engine, split the cases by removing case covers and then the upper and lower case bolts, flip it over and take off the bottom case. You do not need to disassemble the top end. Once the bottom case half is off, you should probably remove the entire old tranny and shift forks and slip the new one in place. There are small locating pins under the main shaft of the tranny and some thin half-moon bits also used to locate the tranny so if they are not on the upper case half, look for them on the tranny ends you took out. These bits tend to get lost.

You might want to take your donor 2nd gear to a machine shop and get it back cut and replace the forks with new ones, if possible.