[Sectorsteve]

since taking the stock muffler off ive disturbed the header pipe so i loosened the header bolts and removed what i think is the gasket. theres a pic here. also theres seems to be about a 5mm gap (see pic) where the header pipe is away from the head. i just cant recall if it was like this. THis is becoming a nightmare now as i need to hire a car and no dealer has a gasket in sydney. Useless. No doubt theyll charge triple the value as well as they do.
Can anyone tell me if this gap between header pipe and head is normal?

[shamelin]

Normal.  Pics to follow.

[Arizoni]

My G5 also has a similar gap between the flange and the machined face on the cylinder head.

[shamelin]

Sorry, had to get the pics off my phone.

My header bolts got loose a few weeks ago and resulted in a loud exhaust with occasional backfiring.  Pic #1 shows the exhaust with the flange and bolts removed; you can see the gap.  Pic #2 is my gasket fix: Permatex copper.  So far, no problems at all. 

It may be something to consider, instead of waiting for a gasket.  I don't know if they sell Permatex in Sydney, but around here it costs about $8 USD.

Good luck.

[Sectorsteve]

That permatex looks alright. Working ok then? I xan get gasket today but I gotta drive 100 miles

[shamelin]

Works great so far, but I've only had it on for about 3 weeks and <100 miles.  Everyone has different thresholds on what they're willing to do, but I'd take the Permatex fix rather than drive 100 any day.

Even if the Permatex fails, you're only out a few bucks.  Either fix will get you back on your bike; it just depends on what you're willing to do I guess.

[wildbill]

what price is the gasket

[Sectorsteve]

Bout 5 bucks but I've just been given 1 from a car muffler joint

[wildbill]

in that case - your back in business. how many k'ssss on your bike

[Sectorsteve]

23000kms now
im back to where i was yesterday. which is with the stock on probably not as good as it was yesterday. Still have the problem of trying to fit the new silencer which has the same diameter as the header. no doubt when i go to do this again, the header gasket will need to be replaced with yet another header gasket. Ideally id like the shims and brackets supplied by the shop that sent the muffler which means another long wait and the shipping cost way above the cost of the goods.
ive been to countless exhausts places today in the hire car and still cant find the right stuff to attach muffler. at the end of the day it may not be worth it to buy something from overseas. its ended up costing more than if i bought it here.

[wildbill]

what i did once to a muffler which didn't hook up in the right position was cut two empty cans of coke in strips. then wrapped that around the header pipe and slid the muffler on.
might work using the same line and something a bit thicker to bed it in. after that you could run a muffler bandage over the join.
appears you have had a good run to 23k

[Sectorsteve]

Bill you read my mind. currently heating some some roofing aluminium on the and bending. im going in. Can i remove the oxygen sensor and also, did the coke cans work?

[wildbill]

oxygen sensor STAYS ON THE HEADER! coke can - cut in slices worked a treat. so would any metal strip that can handle a bit of heat.

[wildbill]

forgot to add . to better the contact point i did rough up both sides of the coke can strips with a bit of 40 grit dry rub sandpaper.
prior to this i had gasses escaping in all directions

[Sectorsteve]

Graham didnt you get my text? I did Sand and i didnt take the o2 sensor off.
so i went up to the shop to get a coke can but i found a dr pepper on route!. the header to head seems ok, although im baffled by the welded great big washer thingy that is about 2 cm from the end of pipe. it sits on an angle and the pipe itself certainly doesnt fit snug in the head. i guess theres around 3-4mm gap around the pipe. i mean it must be right cause , thats how it is, but im blown away how it can be sealed. - no leaks after using some gasket glue and the gasket - not the exact right gasket but...
the exhaust sounds great however theres a weird gurgling type sound on deceleration and the aluminium can is starting to split. the good thing about the silencer is that it can be quiet, however it can be really loud too!
Kind of excited now. def dont feel any more power, but im pretty sure theres leaks galore. i need to get on top of this. im gonna ride it about 60km tomorrow to some jobs, but not before i whack another hose clamp and another coke can on!
i reckon if i can find a big mutha stainless clamp, this will be all thats needed and we should be sweet as.

[wildbill]

that hook bit -is it the one that hold your heat shield plate.....grind it down otherwise you are unable to get the new pipe securely on
mine was impossible to seal with that glob so the angle grinder fixed that.
then i gave it the wrap. 
after that it's a case of looking for an aftermarket heat shield
this is the hook i removed

[mattsz]

My header bolts got loose a few weeks ago and resulted in a loud exhaust with occasional backfiring.  Pic #1 shows the exhaust with the flange and bolts removed; you can see the gap.  Pic #2 is my gasket fix: Permatex copper.  So far, no problems at all. 

Sorry if this info is obvious, passé, or dead wrong, but...

On my bike, that flange holds the header in place, but I think it isn't where the sealing occurs.  My gasket is a smaller ring whose diameter matches the header's and seals the very end of the header to the engine.  So the gap around that flange doesn't matter, as long as the pipe is held securely to the head, sandwiching the gasket between them.  Any sealant around that flange would be secondary.

Is that right?

[Ducati Scotty]

+1 to what Matt says.  The sealing occurs inside the head where the end of the pipe touches.  There's a round gasket in there.  The flange is just to apply uniform pressure.

Scott

[Arizoni]

For what it's worth, aluminum melts at temperatures between 980 and 1200 degrees F depending on the alloy.
I should add that ALL aluminum alloys loose almost all of their strength at temperatures above 450 degrees F, so if the Coke can has to do anything mechanical like hold things together it will fail.

Before someone points out the entire head on the RE is aluminum and it survives I should mention the cylinder head is quite massive and it has lots of cooling fins to get rid of the heat.
It also has a good supply of oil circulating above the valves and this also cools things off a lot.

Aluminum conducts heat very nicely too so the high temperatures around the exhaust port are rapidly conducted away to cooler areas.

Getting back to the exhaust, even at the joint where the silencer attaches to the exhaust header, the temperatures can exceed 1200 degrees if the bike is running hard.

Ideally some sort of stainless steel sheet metal will work to make a joint between the pipe/silencer.  Even plain old carbon steel sheet metal will work.  It will rust but it won't melt.

As a sidenote, I tried filling the space between the the outside of my RE's exhaust header and the inside of my Harley Sportster silencer's inlet end with some aluminum sheet metal.  It melted into little bitty blobs of aluminum and I rarely ride my bike hard.