Exhaust studs/threads

[Rncv]

Hi guys,

today ive been working on the fzr and have stumbled across a problem. I took the old exhaust downpipes off because they were cut and re welded in so many different places. I brought a set stainless downpipes and a copper gasket set and set to putting it on.
So i manage to get them on and then find out that the new studs are too short so turn them out a bit to make them longer (this is where i think i went wrong). The pipes need to squash the copper gasket to seal them correct?

what happened is when i was tightening one of the studs it made a pop and then the thread inside the head was damaged. You can only gently turn a stud but when it gets any force behind it it just pops out.

Any ideas on how to fix this problem? also anyone know where to source fzr 600 3he 1991 studs/bolts? as the ones i have dont seem right.

many thanks.
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Current: 01' Bandit 600, 92' Goose 350
Previous: Lots!

[Babba]

Sounds like you've stripped a few of the threads in the head.

For an effective repair you're going to need to take the head off & get the thread repaired with a Heli-Coil insert.

It sounds like you've only stripped part of the thread, you 'might' get away by sourcing the correct length studs (I prefer allen head bolts) and hope that there's enough good thread left deeper inside the head.

For someone who knows what they're doing, this is a cheap & easy fix (my engineers charge £20ish for a Heli-Coil), for someone on a discovery trip, it could end up costing you a new head?

[Rncv]

[Babba]

Try to use A4 grade stainless allen head bolts, should be OK to use in place of any traditional stud & nut so long as you can get an allen key on the head & not be fouled by the downpipe.

Use copper grease on the threads to prevent them seizing up over time. Aim to remove, re-grease & re tighten at least 2x a year.

Don't over torque the bolts up either, all you need to do is slightly crush the gasket to seal with enough tightness to prevent the bolts vibrating loose.