Exhaust Collector Box Seal

[Suntan Sid]

I need a collector box seal for my project bike, one of these graphite things:-

https://www.cjaccessories.co.uk/images/P/gasket.JPG

My problem is, these things seem to come in a set of standard sizes.
I need a non standard one, I can get one with the correct outside diameter, but the internal diameter is too big by 2mm.
I assume that 2mm is too much of a gap to be eliminated when tightening the clamp?

Does anyone know if you can have these things made to a specific size?

I have some, self adhesive, aluminium tape which I could wrap around the pipe, to take up the 2mm, would this make a seal or would the aluminium disintegrate after being heated up?

Are there any alternative solutions, such as, using exhaust bandage, wire wool, rubber or possibly high teperature silicone?
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"Everybody needs money, that's why they call it money!"

[STONEY!]

Aluminium tape will work for a few months but eventually fails. Bandages, silicone and exhaust putty will get you through an mot but that's about it.

Can you buy one that is slightly too large then cut it down? or make a 2mm thick sleeve to go over the internal pipe? maybe buy a bit of tube with the correct internal diameter and press it on the pipe?

what are the correct sizes you need?

[Suntan Sid]

[STONEY!]

That is an odd size, I presume the join is between silencer and downpipe and the silencer I'm guessing isn't the original?

High temp silicone works well on small gaps but 2mm will need something else to take up the gap I recon. the aluminium sheet should do the job.

I have never used wire wool to seal an exhaust but I did once use it as a tempory baffle to quiet an exhaust down, it worked but didn't last 5 minutes!

[Suntan Sid]

Yes, you're right, the pipe is an odd size, it has had a sleeve welded onto the original downpipe!
It doesn't look, particularly round either, which is why I'm asking about the silicone to take up a small gap?
I'll have a go with the aluminium sheet and see how it goes.
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"Everybody needs money, that's why they call it money!"

[DrDonnyBrago]

Could you use a pipe expander on the smaller inner pipe to get it big enough for a standard gasket?

[Suntan Sid]

[stinkwheel]

I bet silicone will do it.

I used silicone instead of a gasket for the end can on my VFR until I got a new slip-joint section made for it.

Just normal bathroom silicone, nothing fancy.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Suntan Sid]

What I'm going to do for now is, wrap an aluminium strip around the pipe, use silicone to stick and seal it and clamp it up while it sets.
If that looks good I'll fit everything and see how that pans out.
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"Everybody needs money, that's why they call it money!"

[Hop Along Biker]

Hi, Iv'e seen a few posts about graphite crushable seals and i thought i'd let you know of a cheat i have used to good affect and a fraction of the price. Firstly you need to get a Chinese takeaway in the round foil cartons (the ones with very fine crimping around the side). Cut the very crimped side of the foil tray, you may need a few. Now go and get yourself the cheap sticky exhaust bandage that has wire, sticky tape and foil strip. Clean all surfaces that meet. Take a piece of the crimped foil takeaway tin and wrap it once around the pipe that goes inside. When you get a half inch overlap on the foil wrap start applying the sticky bandage. YOU NEED TO KEEP THE WRAP TIGHT. Keep wrapping until you get almost the size of the correct original graphite seal. Keep needing as you wrap to keep everything tight. When you have the correct diameter cut the sticky bandage a half inch shorter than the foil. You can now slide the seal off the pipe (for protection until use) because it isn't stuck.Now make the rest of the seals and a spare set while you are at it just in case you need them. When you are ready open up the receiver pipe so the pipe with seal on just slide in. Now tighten the clamps but not too much. Leave over night if possible to harden a bit now tighten the clamps a bit more . Start the bike if you have any blowing stop and tighten the offending seal. Now start the bike again. If you have no blowing run the bike until the pipes are up to temperature. Again leave a while (overnight if possible) then tighten the clamps just a touch. Maybe keep the power off a bit for the first mile or two then away you go. The reason this works is because it is not thin foil tape but crushable heavy crimped foil and this gives it strength. On top of this you are using a strong heat proof adhesive tape that binds the parts into one whole seal. The seals i have made this way have lasted two years minimum. I had to take the last pair off (there was nothing wrong with them and removal was simple as they where not stuck with gunge) to weld the collector box otherwise they would still be going strong. Good Luck Ride Safe and keep it shiny side up. Ps stay away from the silicon, it rots metal unless you get the very very expensive non acetic acid cure stuff and that doesn't work with the heat of the pipes.
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Hop Along Biker

[Itchy]

You're NOT going to get a pipe expander for 2mm. On my old CBR600F in an effort to save the mild steel downpipes after my big crash it was futile.

I had a breaker bar on it over a metre long and the bike was being tipped over before the pipe would expand any more. I ended up replacing the whole lot of downpipes anyway. TBH why not just make a sleeve and fit it over the end bit then another one on top?
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Spain 2008France 2007Big one 2009 We all die. The goal isn't to live forever, the goal is to create something that will. In the end, your life will flash before your eyes. Make sure it is worth watching.

[Pete.]

[Hop Along Biker]

Construction expansion bolts can be used to good effect. Get a very large expansion bolt from a builders merchant and use metal strips (or wood if that's all you have) and tape them around the unexpanded bolt until it just fits in the pipe you want to enlarge. Now start expanding the bolt, it may slip a bit at first but when it starts to tighten it should grip. if for some reason it doesn't grip loosen it and put a couple of strips of course emery cloth or other rough stuff around it. Expand the bolt to the size needed, if i it won't go that big back it off pack around it a bit more and continue like this until things fit. If you need a lot of expansion then get a local garage to make up (or do it your self) sleeves to make the small pipe fit the large one.
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Hop Along Biker

[MCN]

High Temp Silcone Adhesive 1200ºC

Stands up to flames 'n' url
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[stinkwheel]

I've used ordinary £2.50 bathroom silicone between the header and cylinder head of my air-cooled enfield. Was fine.

You don't need to spend a fortune on special "high temp" stuff.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.