1978 XS1100 Exhaust Flanges

[Sweenes]

Hi all Im new to the forum. Just finished rebuilding by xs11. On first startup there is smoke leaking from the headers. When I tighten the nuts once it warmed up a couple of them bottomed out. I did notice there is a flange on each mount but it is not the finned flange. Any suggestions definitely appreciated! Thinking washers or but the finned flanges. Thanks!!!

[Radioguylogs]

If you are considering washers, you must mean the nuts don't engage deep enough on the threaded studs (not the flange touching the manifold).

The OEM nuts are hollow all the way through so the stud can thread completely through them...even though you still need enough purchase for an allen wrench to tighten them.

The OEM nuts are still available at Partzilla for $3.31 each.

[MaximPhil]

Hi all Im new to the forum. Just finished rebuilding by xs11. On first startup there is smoke leaking from the headers. When I tighten the nuts once it warmed up a couple of them bottomed out. I did notice there is a flange on each mount but it is not the finned flange. Any suggestions definitely appreciated! Thinking washers or but the finned flanges. Thanks!!!

Welcome Sweenes, Did you install new header gaskets ? After market exhaust flanges are much thinner than OEM so the acorn nuts of the allen head nuts probably need to be replaced with regular nuts.

Phil

[TopCatGr58]

Hey Sweenes, the exhaust ports in the head does have a recessed flange area, that's where the exhaust gaskets fit into along with the header pipe. Did you put in new gaskets? They are crushable. Sometimes they are burned and stuck in the head, almost looks like the head material itself, and can get left in, then folks put new gaskets on top which can actually be too much, and can prevent the header pipe from seating which can cause the flanges to not go on far enough and not allow enough of the header stud and threads to stick out far enough past the flange surface to allow a good purchase of the nut. But your description is the flange is too deep so the nut stops on the non_threaded portion of the header exhaust stud. So possible that the stud got partially threaded from the head when you loosened the nut and didn't realize it's sticking out? Or you put the old exhaust gaskets back in, and they are already too crushed to allow for a good seal?

[Bax]

Hi Sweenes, Welcome to the club. If you post a pic along with the issue it helps us help you.

---Bax