So I need to also add to the shopping list 2 M9 bolts? It doesn't say that in the manual.You cut off just the head so that you will be able to slide the cylinders over the bolts, from the top -- use a hack saw, or an angle grinder if you have one, to cut the bolts -- you want to keep the bolts as long as possible, so don't cut off any more of the shank than necessary (i.e., just your blade width).
You won't torque the cut bolts -- you just screw them in a short way (see the updated picture above -- a good chunk of threads are still showing in the red circle) into 2 of the 6 holes in the crankcase with your fingers, then use them to align the cylinders as you lower the cylinders onto the crankcase, and once the cylinders are aligned and lowered, you unscrew the cut bolts with your fingers and remove them, and then install the original/real (i.e., uncut, with heads that can be torqued) 6 bolts thru the now aligned cylinders into the crankcase, from the top.
Nothing of the 2 cut bolts is left in the engine -- keep them and you can reuse them next time you take the cylinders off...
As it says in the diagrams, 92154? 2018 Kawasaki Ninja 400 (EX400HJF) Cylinder Head | Babbitts Kawasaki Partshouse
Now do you make that 2 bolts, or replace the whole pack and go with 6?
Also regarding the head, in the manual it says you need to replace the 4 orings there - 2018 Kawasaki Ninja 400 (EX400HJF) Cylinder Head | Babbitts Kawasaki Partshouse
Labaled in the above link diagrams "92055" and "92055A/C"
A and C 92055 is a two different orings, there are 4 orings there acoording to the manual, yet it does not tell which one is which but from the picture it looks like 2 types (92055 and one of the A and C).
Which one do you get. Or just get 2 of everything..