250-500cc Can we use A2-70 stainless bolts for cylinder head ?

Hi all,
I was searching about this and did not find anything really....

My WR300 has six M8 bolts in the cylinder head, OEM are pretty expensive so I went for some 12.9 hardened stell bolts but those are only available in a black finish that is sensible to stain / rust so I painted them black to prevent that.

My question is, would stainless A2-70 bolts hold up ? I think they would but I like to get confirmation from someone who knows better.... AFAIK A2-70 have a similar tenside strengh than steel 8.8 bolts, is that enaugh for a cylinder head ?


Regards.

Heads arnt that tight, what's wrong with std zinc plated m8 steel ones?

These are also only available as 8.8 at least the standardindustrial ones...

Well i would choose mild over stainless just because ive heard stainless work hardens, but once its torqued up the bolts are just under tension.
Never had an issue with my head bolts tho.

Perhaps a more technical guru will be along to put me in my place. (Hope so i like knowing why to do things)

Yes, not a good idea from what I know. It hardens and get brittle. Again, I'm not a metallurgist but I have always been advised against it.

12.9 should be adequate. If you are worried about staining you could always get them electroplated.

8.8's are whats in my head you will be fine

Thanks all,
AFAIK A2-70 have a tensile strength similar to Steel 8.8, but I'm not sure on the brittle issue you are commenting ...

Regards.