Exhaust and downpipe packing

[koolio]

This is my first time doing this so would like to get it right, hopefully you guys could help..

I've got a set of old CB450 downpipes and I've paired them with a set of Harley sportster exhausts which have clamps. Both used.

They fit perfectly.

Question is do I need to put packing or a gasket between the down pipes and exhaust? Just where do I get this and what size am I meant to get?

Would be appreciated and sorry for the noob question, never touched exhaust systems before...

[Wafer_Thin_Ham]

What's the diameter of both, and what do you mean by "packing".
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[koolio]

I don't mean the gasket at the head between the cylinder and the down pipe.

I'm just wondering if there shouldn't be a gasket between the downpipe and exhaust. I've seen it referred to as a gasket or packing (I don't mean the packing inside the exhaust).

Downpipe is 42.8mm
Exhaust unclamped is 44.5mm

[Wafer_Thin_Ham]

Some bikes use a gasket, some do not. Clamp it up, see if it leaks.
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[koolio]

If it leaks any ideas of what to do? This is a CB450 downpipe with a harley sportster exhaust, so not stock..

[Kickstart]

Hi

While some bikes have a kind of tube gasket between pieces (FZR600 for example) the chances of finding one to suit are probably limited.

The thickness of any 'gasket' in this case is about 0.8mm. If you slot the outer the it would clamp down easily (possibly with some kind of sealant). Failing that possibly knock up a thin wall copper tube of the appropiate dimensions

All the best

Keith
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[koolio]

Thanks guys I may go with an original CB450 muffler gasket and see if it fits..

[koolio]

Bad news the exhaust does not clamp onto the downpipe on its own and the graphite gasket for the CB450 is far too thick to accept the exhaust.

Anyone any ideas how to get around this? Can a graphite gasket be machined down?

[gavcarter]

[koolio]

Thanks maybe I just need exhaust paste, I'm talking about roughly a 1mm gap between the exhaust and downpipe?

[gavcarter]

Paste tends to go dry and crumbly but its worth a try - It will more than likely hold up for a good amount of time if you left it to "air dry".

If you fire it up when the paste is wet - it will likely blow out all over the place.

If the paste fails use cheap bathroom sealant! wilkos own tends to work well. No seriously, it dries rock hard but actually adheres the two pipes aswell - it can take some prodding and poking to separate them again but it will seal the gap no probs.

A third option is to use a strip of 1mm metal as a gasket with a light coating of paste on either side.

[koolio]

Ok this is great help..

Will the bathroom sealant withstand the heat?

If I got the graphite to a good fit surely clamping that down would suffice or would I still need the sealant?

[gavcarter]

[koolio]

gav thank you a lot.

I can see the graphite rings now trouble is I would literally need to halve the graphite gasket to get it to fit, I hope it holds up..

[gavcarter]

[Kickstart]

Hi

If you have access to a lathe you can probably machine up a tube spacer to go between them.

As to sealant, flue sealant is a high temp silicone sealant and should be fairly easy to source.

All the best

Keith
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