CB400f exhaust gasket size

[wildtapholer]

Hi again, I ordered an exhaust to collector box gasket from David Silvers and this is what came, and it was way tooo big does anyone have their exhaust off at the moment that could measure the collector box neck and the exhaust internal measurements, mine is 38mm at the collector neck

[wildtapholer]

I've rung Silvers this morning but they're not having it that the gasket is wrong, they're saying it will crush down and I'm telling them it won't go in the exhaust to crush down, and to crush down from the size what came is ni on impossible. I told them even if I put the genuine part no down on their web site, it doesn't give what the size is but they're quite prepared to order me one and I'm getting really annoyed. They suggested it might be a rouge gasket and they will take one out and measure it, but I told them when you put the part number in, what they sent is, it's dimensions as 48.9x43x30.3  I bought one exhaust gasket from M&P it was too small, I hadn't measured the collector box at this time, so ordered one from Silvers and it's too big and that's when I measured the collector box neck 38mm arhhhhhhhhhhhhhhh

[billywingnut]

I recently bought a silencer and  gasket from DS and had the same problem. I used coarse sandpaper to reduce the outside diameter of the gasket until it was a snug fit inside the silencer. This means the walls of the gasket are quite thin but it did work after a couple of hours of rubbing. It now works a treat, there is a slight leak of condensation from the joint when cold which I am advised is not a bad thing as it drains the silencer, the joint does not blow however.

[wildtapholer]

That doesn't tell me which gasket you got or part no what they sent or what size it was, if the collector box is 38mm and the internal measurement of the exhaust is 42mm there is no way the 48.9x43x30.3 is going to fit, this is what I had to do, pic enclosed, I had to cut more or less 2cm out out the gasket what was sent

[smoothoperator]

My silencer is off at the moment and the gasket is still on, so I have taken measurements. There is some ovality so using average measurements, I have outside diameter 48.0 mm, Inside diameter (outside diameter of the COLLECTOR BOX PIPE), 42.5 mm, length 29 mm.

[wildtapholer]

What's the collector box neck measure at if your able to measure that please.

[smoothoperator]

Sorry I wasn't clear, the 42.5 mm is the o/d of the collector box neck that along with the gasket slides into the silencer. The silencer splays out to allow fitting the collector box with gasket inside it, with the clamp pinching the splayed out end of the silencer back in as the clamp is tightened up. I have edited my earlier reply to make this clearer.

[wildtapholer]

I can't understand why my collector box neck only measures 38mm on the outside, this is going to cause me a lot of trouble trying to get the correct size.

[Nurse Julie]

I can't understand why my collector box neck only measures 38mm on the outside, this is going to cause me a lot of trouble trying to get the correct size.

Have you got a photo of your collector box?

[wildtapholer]

Just seen this message, I'll pull the silencer off tomorrow and try to include a picture with the vernier gauge across  the neck of the collector box, but as far as I'm aware it's standard.

[hairygit]

How are the downpipes held to the collector, 2 welded, 2 clamped or all 4 clamped?

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[wildtapholer]

The pipes were a bit rusty so I cleaned them up and painted them with heat resistant paint but other than that they are fine except for sourcing a gasket, so here's 3 pic's if it let's me up load them.

[Deano400]

Original double skin headers.
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[Deano400]

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[hairygit]

So the fact is Bitsa will be laughing his head off again " F%*king pattern parts!"
He may have been a cantankerous argumentative old git, but he talked a lot of sense.

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