I did a complete teardown on my 1981 years ago. Parts were hard as hell to find, availability and aftermarket support comes and goes. The replacement ignition module for the 81 model year was made by a guy in Finland I think they are no more. Just be aware if your ignition dies you have to find a working module as the 81 is a stand alone design. They even changed the engine cases, so you can't retrofit.
I had a thread on KZrider chronicling my build but the attached images are long gone. Here was my punch list for a rough Idea of the project. I included my parts for the carbs and the electrical work as some of that is related to the engine build.
Finding everything was the fun part. I had to source parts from the UK, Finland, Germany, Japan, South Africa, and all over the US.
I really enjoyed the project, it's a very unique engine, cutting edge for it's day. My advise is not to cut corners, do it right the best you can with the parts you can source. Tear down, inspect and evaluate, then make a list and go for it. It's best to run the engine before a tear down and take note of the obvious issues, if it's not a running engine you are going in blind looking for possible problems, and sometimes that is what you have to do.
Here was my list.
Parts and Repair List
Carburation/Induction
Carbs ultrasonically cleaned
Enrichener tubes repaired
(3) Carb Kits (Z1-Enterprizes)
(3) Brass Floats (Forum Member at KZ1300.com)
Jet Kit (6 Sigma, Cheap on E-bay)
Air box Top “Snorkel” Replaced
Carb Boots (Used E-Bay)
Pingle Fuel Tap w/Adaptor (Dennis Kirk)
Fuel Line and Filter
Uni Air Filter (E-Bay)
Fuel Level Gauge (Used, E-bay)
Engine
All Engine Mount Bolts and Nuts (Used, E-Bay)
Gasket Kit (Generic)
OEM Base Gasket
Custom Comitec Head Gasket ( they have the pattern if you call them)
OEM Timing Chain Rollers (Updated Version)
ZX-10 Tensioner ( modified spring for proper tension)
Timing Shaft (Used, E-bay)
Water Pump Drive Gear, Plastic (Used, E-bay)
Water Pump Mechanical Seal
Water Pump Oil Seal
Thermostat (OEM)
Thermostat Cover Gasket (OEM, pattern gasket was crap)
Radiator Hoses (Cut Pieces from Single Automotive Hose from NAPA)
Colling Fan Switch Sensor (OEM)
Repaired Colling Fan Wiring
(6) Forged Pistons from Ross w/Wrist Pins and Clips
(6) Total Seal Piston Ring Sets
(6) Vesrah Intake Valves
(6) Exhaust Valves (possibly Vesrah from the UK)
(12) Valve Seals, Steel Bucket Type from Z1-Enterprizes
A Few Valve Shims (Two from Z1-Enterprizes, One from E-bay)
SS Allen-head Bolt Kit (E-bay)
Custom Blanking Plates for Emissions Reed Valves ( self fabricated)
A Ridiculous Number of O-rings (All OEM)
Valve Job, Re-Surface, and Mild Porting from Cavanaugh Racing
Cylinders Bored by Quality Machine in Fargo, ND
(4) Rubber Cam Plugs form Z1-Enterprizes
OEM Clutch Cable
Chrome Engine Covers Stripped and Polished
Ignition and Electrical
(3) Dyna Coils, Green (Ebay, One at a Time)
Fabricated a Plate to Mount Coils Where Tool Tray Would Normally Be
Added Wires and Loom to New Coil Location, Threw Old Coil Resistor in Garbage
Spark Plugs, NGK
Plug Wires (Generic Automotive 6 Cylinder Kit)
Battery, AGM Type (Batteries Plus)
Battery Tray (Used, E-bay)
Battery Hold-Down Bracket (New OEM, Found One Cheap Old Stock)
Rear Turn Signals (Generic ones from Dennis Kirk)
Turn Signal Stems (Used Parts I Already Had)
Rubber Mounting Grommets for Turn Signals (American Classix)
Repaired Wiring for Rear Lights, Replaced Diode for Running Lights
Cleaned all Connectors, Replaced Stator Connector and Contacts (Z1-Enterprizes)
Lower Head Light Bracket with Rubber Parts (from Germany)
Rubber Side Mounts for Head Light (OEM)
Spare Ignition Module (from Lauri in Finland)
Miscellaneous Other Crap
Screws, Nuts, Bolts, Washers, Etc.
Used Bore Gauge (E-bay)
Sealants, and Silicone
Honda Bond 4 (for the Water Jackets in the Head Gasket)
Grease, Gear Lube and Engine Oil (Filter Too)
Assembly Lube
Antifreeze
Permatex Gasket Remover