Exhaust header gaskets

[martygrohl]

Hey guys, need help on this one.

Doing a good bit of work to the Storm just now and one of those things was dropping the exhaust system to polish it all up.
I'm now trying to reattach the exhaust with all new gaskets and clamps. The header gaskets I got are aluminium fibre (https://www.wemoto.com/bike/honda/vtr/1 ... nium-fibre).
I can see that the current gaskets are copper, which are slimmer than the aluminium fibre ones (even when new).

I attempted to torque the downpipe back on with new bolts and studs but the downpipe was sitting away out from the engine surface (gap showing bolt thread).
Is this correct if using aluminium fibre gaskets?? I assumed they would squash a lot more, getting them to the copper gasket thickness.
But what I've ended up doing is warping the downpipe eyelets because it looked like they needed torqued down more (which was way too much, 12nm is the spec).







*Another job I was doing was removing and repainting the subframe, so will post that up soon.

[xeris]

Maybe they will be fine. OEM parts is all I would consider, especially given the price, for engine related parts.
You most certainly don't want to shear the studs.

[martygrohl]

Yeh I usually go all OEM, but every single parts store other than David Silvers sells the aluminium fibre gaskets.
Only just checked DS as well, it’s usually my first port of call.
(https://www.davidsilverspares.co.uk/VTR ... art_66661/)

I’ll order new copper ones. It just seems weird that the most sold gasket replacement makes the headers sit way out.

The rear studs came out ok, albeit the nuts were seized to them. However the usual story with the front studs, sheared, seized and stuck. Trying to grapple them out before resorting to carefully drilling.

[sirch345]

Maybe they will be fine. OEM parts is all I would consider, especially given the price, for engine related parts.
You most certainly don't want to shear the studs.

I'm the same on OEM parts, however I can’t see the difference of compression between using the gaskets you have and the OEM parts being more than a few millimetres in difference.

So are you trying to achieve the impossible of reducing the gap between the collar on the exhaust header pipe and the exhaust cylinder port to less than what it normally is

Chris.

[martygrohl]

The copper gaskets seat better and when the header is connected, it is flush with the engine port.
The aluminium fibre gaskets create a gap because they are thicker (but I thought they were supposed to compress and crush on installation).

The aluminium fibre gaskets create the gap you see in the image, even when torqued.
I assumed that as these gaskets are meant for the Firestorm, they would sit properly and allow the header to be reinstalled as before.

I didn’t find any post on here yet about aluminium fibre gaskets and this issue so I was posting to see if anyone had an idea what I was doing wrong/should the header sit that far out, or be useful for anyone else going to buy them so they know this issue.

[sirch345]

The copper gaskets seat better and when the header is connected, it is flush with the engine port.
The aluminium fibre gaskets create a gap because they are thicker (but I thought they were supposed to compress and crush on installation).

The aluminium fibre gaskets create the gap you see in the image, even when torqued.
I assumed that as these gaskets are meant for the Firestorm, they would sit properly and allow the header to be reinstalled as before.

I didn’t find any post on here yet about aluminium fibre gaskets and this issue so I was posting to see if anyone had an idea what I was doing wrong/should the header sit that far out, or be useful for anyone else going to buy them so they know this issue.

I don’t recall anyone else posting about aluminium fibre gaskets either.

I had a quick look on my Storm earlier, both front and rear header flanges sit approximately 3mm away from the exhaust stud bases, and that is with Honda OEM copper gaskets fitted,

Chris.

[tony.mon]

Did the old gaskets come out when you took the headers off? They often stay in the port on disassembly, and then you get the problem you describe, as you're trying to fit a new gasket on top of the old one. Try using a pick or screwdriver to make sure the port is "empty".

[martygrohl]

Thanks for checking Chris.

The old gaskets never fell out, I had to pick them out like you say. They’re copper so easy enough to see, and they sit neatly in the groove of the outlet.

I took these out before trying to re-install, I know that’s a common issue though if you don’t notice them. They can get covered in suet.

This is why I know they’re copper gaskets and how I could do a comparison photo. It’s just really weird that the fibre gaskets are most commonly found everywhere and anywhere else but David Silvers, specifically for the Firestorm. Perhaps they work ok with aftermarket exhaust systems.

I’ve got copper gaskets on order now. This post will at least help anyone else coming across this issue on the 20+ year beaut!
I’ll add comparison photos of headers sitting with new fibre and new copper gaskets to show the difference.

[martygrohl]

Ok got the copper gaskets delivered.

They are obviously dead right and start out a little thicker (as they crush into place when installed), but the aluminium fibre gaskets are way more rigid so they don't crush as much at all.

This is how the downpipe looks with an aluminium fibre gasket in. It sits way far out, it may work, but it just looks wrong.



This is the exhaust port clear of any gaskets (notice the slight indentation round the inner cuff to seat the copper gasket.



With the copper gasket seated (some copper ease on it to hold in place).



The downpipe being screwed on to torque spec of 12nm (half turn each side at a time).





The difference in thickness of new aluminium fibre vs copper gaskets.



NOW
On to the next problem before installing the exhaust again, front sheared/seized studs (extractor bit, welding, or maybe drilling to ensue)

[sirch345]

Hi Marty, I'm glad you have it sorted now regarding the new copper gaskets

Fingers crossed all goes well with the sheared stud, patience is your best friend in this instance

Chris.

[martygrohl]

Sheared stud was an absolute nightmare, as per most experiences.
One of the front studs so pretty damn seized.

I tried a dremel cutting disc to get a flat surface. 2 small carbide tip drill bits which only cut in so far. An extractor bit which ended up shearing in the cavity.
Then tried a larger carbide tip bit to bore it out which was only 1-2mm less than the thread. That went so far, then I used yet another drill bit, this time a red carbide makita bit which managed to cut all the way through the stud to the bottom of the chamber which was ideal.

Tried two other extractor bits in the deeper cavity, with absolutely no luck (using a tap wrench).

Ended up placing a torx bit (T30) in the cavity, and hammering it in place. Heard it’s a mechanics trick for extracting sheared studs.
Used a socket to counter turn the torx bit and FINALLY!!! The stud came loose. Hell of a torment this one.

Each step here, I switched between adding WD40 into the cavity and applying heat with a handy blowtorch.

[sirch345]

What a metal surgeon you are, well done
That one certainly tested you to your limit and beyond I'm sure. Most would more than likely have had the cylinder head off to work on it at work bench, good job,

Chris