Exhaust Making high temperature exhaust gaskets

Discussion in '2-Stroke Engines' started by smurfer, Nov 15, 2006.

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  1. Steve Best

    Steve Best Well-Known Member

    Hi RA1977691, that post you replied to is 8 years old. Looking at his history, Nik hasn't been around for those 8 years either.

    The colour of the bolt does not tell you anything about it. It is just a surface treatment and could be heat treatment, Parkerizing or some other cosmetic coating/treatment.

    Your information is 20 or 30 years out of date. Cheap bolts these days come from off-shore and are sometimes made from sub-standard steel that may be brittle if heat-treated to a hardness (which would make them black, true enough). The plain grey bolts are typically not heat treated and do bend without cracking. This is still a lot of guessing and conjecture. The answer is to buy good brand name bolts and studs in grade 8.8. Here is a chart to give you an idea of where to find that info on metric bolts:
    Below is the marks on the nuts

    zippinaround likes this.

  2. butre

    butre Well-Known Member

    black doesn't mean hardened steel, it means either black oxide or black zinc. if you're breaking either one, you're either overtightening or grossly undertightening them. anything you buy from lowes or home depot is cheese grade trash.