Bolts for exhaust header question Gen3

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I have recently removed my factory exhaust in preparation for a full system upgrade. A few top bolts were bent so I have decided to replace them all with stainless. Factory bolts are steel and are marked grade 10.9
My new stainless bolts are A2-70.
I am unsure why the factory bolts would have been torqued to the point of yielding considering torque spec is 17lbf-ft but now I’m using a “weaker” stainless bolt as a replacement…. Should I purchase stronger stainless bolts? It just seems excessive considering they are threaded into aluminum. Anyone know why the factory bolts would have been bent? This seems like a common occurrence on previous gens as well

 

[Berlin Germany]

the only stronger stainless would be a a2 or a4 - 80

that is the max strength at stainless bolts etc,

and try to get the A4´s (instead of A2) they are better in resistance against salty air / water
if the bike rests closer than 40 miles to sea-line (ocean side) a A4 quality is almost unavoidable.

and use always a ceramic paste at the threads (into alu)

 

[pcs]

a few of mine were also bent when i changed my exhaust. i replace the bent ones and use a little anti seize on the threads. you likely won’t have any issues with those bolts. just don’t forget to replace your exhaust seals too. the 3rd gen uses one time use seals. i swapped to gen 2 oem seals since they are reusable but that isn’t necessary.

 

[sixpack577]

This^
Anti-sieze and new gaskets.

Rule of thumb is 10% less torque when using anti-sieze on a ss fastener that is going into aluminum, but, some bolts may need a little more torque than called for, another reason some of the factory steel bolts were bent.
Given that there are 4 seperate unsupported tubes going into a flush surface, there can be some variance in the force needed to get a good compression seal on the new gaskets.
Just start it and test for air leaks Before you reassemble it.
And you can safely run the engine for several seconds without the radiator installed.
This gives you room to move a sheet of paper around the tubes, which will make any air leaks very easy to see.
I have also used ss header bolts on several bikes over the years, without any issues...and they look much better, lol.
Most of the readily available ss fasteners are around the same tensile strength as steel, but even though the ss will bend some, it is more of a brittle material...and also not something fun to remove if it breaks off, but, just be careful and you won't have any problems.
Pictures are my Gsxr1k, but basically the same thing.

 

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Thank you all for the replies. Will continue with the A2-70 and add anti seize. Wish I knew I could use the gen2 gasket as I have been waiting on those gen 3 gaskets for a week from eBay. I’ll call my local dealer to see if they have the gen 2 in stock.

 

[Bumblebee]

I wonder if exhaust bolts being bent is a gen 3 thing...?

Seems kind of an odd thing to be bent, I've never encountered a bent exhaust bolt on any of my bikes...

 

[sixpack577]

I wonder if exhaust bolts being bent is a gen 3 thing...?

Seems kind of an odd thing to be bent, I've never encountered a bent exhaust bolt on any of my bikes...

I have seen a few, and on factory headers.
The flanges were slightly bent too, but after the flange stopped bending, then more of the stress went to the bolt, bending it.
What is more impressive...or more indictive of a poor quality steel bolt(too soft), is that the aluminum threads in the head did not strip.
Thankfully and suprisingly I have yet to have to repair header bolt threads on a 4 cylinder sportbike engine, and I have seen several aftermarket header flanges bent from bad installs...and bent bolts as a result.
Of course this is caused by inexperience, by not using a torque wrench, and reusing old gaskets, gaskets that they have to further crush(over tighten) to get a decent seal out of.
As for the Gen3 getting some poor quality exhaust bolts, or a defect in the assembly process, I would say neither is a difficult thing to to see happening, not to mention all the other issues many Gen3's seem to have.

 

[Berlin Germany]

I wonder if exhaust bolts being bent is a gen 3 thing...?
(...)

no bee isn´t

the bent screws i found different times also at gen1 and 2

i guess the owners/tmechanics used too much torque when reass. the downpipes again.

i start always with 10-15 Nm instead of the 20 Nm (see manual)
and do then a short running test - yes without the water cooler
if the seals are working fine.
if/when a seal "chirps" i give softley!!! and with a lot of feeling the 2 screws a very little bit more torque with my ratchet til that gasket stops "chirping".
the flange should be parallel to the head !

and don't worry - without a cooler, absolutely nothing will happen to the engine if it runs for 2-3 minutes without