Metal grade of Engine Mounting Bolts

[HL500]

I've seen some restored bikes with stainless engine mounting bolts.  These are low grade as far as I am aware.  Do mounting bolts need to be high grade or are mild steel bolts ok for this purpose?

[Slakewell]

I dont like using high tensile bolts for engines. They snap were a low tensile bolt will stretch.

[PEZBerq]

Best stick with 10.9 grade high tensile in my experience. I have stretched the threads of 8.8 grade engine mount bolts torquing up to Husky spec and had to cut the bolt to get it apart as the nut would not come off. Very annoying  Never snapped one by torquing to spec.

[tymes]

Ive never snaped an original factary engine bold nor a stainles one. But if you use stainless its a realy good idea to use thread lubricant or they tend to bind the treads.

[Rossvickicampbell]

if using s/s bolts and nuts must use different grade bolt and nut otherwise they will bind severely.

[Nathan S]

The stainless bolts I buy from the local bolt place behave something like an 8.8 or maybe a 10.9 - I wouldn't rate them as "low quality".

[yamaico]

The stainless bolts I buy from the local bolt place behave something like an 8.8 or maybe a 10.9 - I wouldn't rate them as "low quality".

Your bolt guy is telling you porkies Nathan. Even the best stainless bolts have a tensile strength below that of a grade 5 bolt. I did a lot of research on this as part of a problem with bolts shearing in a saltwater application.
Edit: Unless he's selling you Bumax 109's, which are not common and quite expensive. Most bolt shops just sell the garden variety 304/316 bolts.

[GMC]

Stainless has some strange attributes.
It will appear hard if trying to cut it with a hacksaw but it is a soft material.
I like the button head Allen head screws for their sleek look but this style has a shallow hex indentation and will chew out easily when doing them up.

[Davey Crocket]

Stainless is for boats and Harleys.

[jimson]

My ex wife is stainless, she thought she looked good, but always broke under pressure lol jimson

[80-85 husky]

lol