kz frame

So I bought a frame, 79 1000 B. the right lower motor mount threaded inserts going through the frame are rusted,bolts broke off and their needing replaced. Ive talked to a machinist and he advised using 4130 chromolly and he would drill and tap the inserts does anyone know the thickness of the frame tubes? This seems scary to me.but it must be done. Ive built an engine cart so I have the dementions needed and bolting up the mount plates I should be close. Has anyone else have any experience in this area to add a comment?

i currently have a kz 1000 frame cut in half(i'm replacing an engine cradle).i haven't measured the tube thickness yet.but just eyeballing it looks like .090 thousandths.it doesn't look like an eight inch.
but i have always thought that my 1980 z1r felt much heavier to move around than my 1978 z1r and have wondered if the later frames weren't thicker????
prolly can't check it tonight but first time i can i will and i'll report back.

leon

I read somewhere (maybe here) that the earlier Zs had small diameter tubes with a thick wall and the later models (my csr for example ) had fatter tubing but with thinner walls.
For what thats worth.

The frame tube thickness is only around 2mm max.
I've dealt with rusted and broken bolts in those lower inserts a hundred times and have always managed to get the remains out without resorting to the extreme of removing the threaded boss's.
Any decent mechanic should be able to remove the broken bolts with a little heat and a carefully aimed drill bit etc followed by an easy out and an m8 tap to clean out the threads.
Even if you destroyed the original thread in the boss there's enough meat to either re-thread to m10 or fit a threaded insert.

Try soaking the broken bolts for several days with Kroil penetrant, then attempt removal

I've drilled and chased the threads with the same size taps.
Steve

I'VE BEEN SOPPING THE KROIL with a sock tied around it for 3 days now the rust has eaten away everything back to the welds. Maybe I can grind the bosses flat and shim them up. Idk Ill see what happens when I get there