Author Topic: Exhausting mystery.  (Read 2748 times)

Offline Athame57

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Exhausting mystery.
« on: August 16, 2026, 07:10:33 PM »
Where to start? A friend pointed out to me that the silencer on my bike hung suspiciously low. Looking at images on the web I can see it now. The silencer I have was recently identified on this forum as a non standard Thruxton that should be no issue, but I'm beginning to wonder if it was ever meant for a CB400F at all. There is no gasket between the silencer and collector box (is that normal for a Thruxton?) Fitting this system when I take it off is the devils own work, and especially since I got the after market header pipes and collector box, I blamed them but maybe it is really the silencer. Could this be why previous owner down he line never fitted exhaust gaskets in the ports, to make fitting easier? I'm beginning to wonder. Trying to raise it's position has another issue, the bolt that secures it to the rear sub-frame would get in the way of the centre stand, see photo 2 below. The bold slides into the housing on the silencer head first. I see on DSS that the housing for the dual fastenings has captive nuts built in lacking on my single one.

By now I have on my bucket list a DSS pattern silencer, but that isn't sold with the fittings I would need, and I can't find those on the CMSL diagrams either, maybe I just failed to identify them? Whatever, until I know what they look like and have a part number to help me hunt them down there doesn't seem to be a way forward, can anyone help with this?
I brake for animals!
1978 CB400F2 named Elen.

Offline Coppertop1234

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Re: Exhausting mystery.
« Reply #1 on: August 16, 2026, 07:24:17 PM »
Hi I just fitted ds repo to my 400 complete system included all brackets
Yes it does look like yours is very low
I can take some pics if it will help out

My muffler has the fittings for a stepped bracket to the rear set with 2 bolts.

« Last Edit: August 16, 2026, 07:27:12 PM by Coppertop1234 »
I Love Tinkering with Old Classics
1970 Mobylette 50cc  
1972 Honda Cb175
1974 Yamaha Rd250  
1962 Triumph 650 Bonneville
1972 Norton Commando
1978 Honda CB400/4
1976 CB750F1 
1976 Suzuki GT750 Kettle
1978 Honda CB 750 F1 
Married Life No Bikes for a while then
1975 CB Honda 400/4 Restoration
1976 Kawasaki Z650   Restoration
2002 Suzuki GSX1400
1976 Honda cb750F1  Restoration
1978 Honda cb750 F1 Restoration
1977 CB 250 Dream    Restoration
1977 CB400/4  - The last one - Restoration

Online exvalvesetdabbler

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Re: Exhausting mystery.
« Reply #2 on: August 16, 2026, 07:25:51 PM »
Does look to hang a little lower than standard.

The OEM exhaust  also has a rubber stopper to catch the main stand.

Regards
Dave

Offline taysidedragon

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Re: Exhausting mystery.
« Reply #3 on: August 16, 2026, 07:27:35 PM »
Your non-standard exhaust hanger is too long. A slightly shorter one would lift the silencer to the right position. Also, the standard exhaust bracket has a rubber stop for the centre stand to rest against. Your centre stand is sitting much higher than it would be normally.
Gareth

1977 CB400F
1965 T100SS

Online exvalvesetdabbler

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Re: Exhausting mystery.
« Reply #4 on: August 16, 2026, 07:30:36 PM »
[ Guests cannot view attachments ]

Phone flat on the floor using the selfie camera.  I knew there was a reason for someone inventing the selfie camera

« Last Edit: August 16, 2026, 07:32:25 PM by exvalvesetdabbler »

Offline Coppertop1234

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Re: Exhausting mystery.
« Reply #5 on: August 16, 2026, 07:33:50 PM »
Bracket from cmsl
I Love Tinkering with Old Classics
1970 Mobylette 50cc  
1972 Honda Cb175
1974 Yamaha Rd250  
1962 Triumph 650 Bonneville
1972 Norton Commando
1978 Honda CB400/4
1976 CB750F1 
1976 Suzuki GT750 Kettle
1978 Honda CB 750 F1 
Married Life No Bikes for a while then
1975 CB Honda 400/4 Restoration
1976 Kawasaki Z650   Restoration
2002 Suzuki GSX1400
1976 Honda cb750F1  Restoration
1978 Honda cb750 F1 Restoration
1977 CB 250 Dream    Restoration
1977 CB400/4  - The last one - Restoration

Offline Athame57

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Re: Exhausting mystery.
« Reply #6 on: August 16, 2026, 07:47:00 PM »

Phone flat on the floor using the selfie camera.  I knew there was a reason for someone inventing the selfie camera

Your back breaking efforts have shown me what the missing fitting bracket probably looks like.  ;)  Alas, still can't find it on the CMSL diagram so as to retrieve  apart number.  :(
I brake for animals!
1978 CB400F2 named Elen.

Offline Coppertop1234

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Re: Exhausting mystery.
« Reply #7 on: August 16, 2026, 07:54:28 PM »
Is this what you need from cmsl site
18353377610P
I Love Tinkering with Old Classics
1970 Mobylette 50cc  
1972 Honda Cb175
1974 Yamaha Rd250  
1962 Triumph 650 Bonneville
1972 Norton Commando
1978 Honda CB400/4
1976 CB750F1 
1976 Suzuki GT750 Kettle
1978 Honda CB 750 F1 
Married Life No Bikes for a while then
1975 CB Honda 400/4 Restoration
1976 Kawasaki Z650   Restoration
2002 Suzuki GSX1400
1976 Honda cb750F1  Restoration
1978 Honda cb750 F1 Restoration
1977 CB 250 Dream    Restoration
1977 CB400/4  - The last one - Restoration

Online exvalvesetdabbler

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Re: Exhausting mystery.
« Reply #8 on: August 16, 2026, 07:56:12 PM »
Is this it
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Offline Athame57

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Re: Exhausting mystery.
« Reply #9 on: August 16, 2026, 08:07:23 PM »
Coppertop & Dave, that's it. I've found the part on 400Four spares so I'll see what Steve quotes before I fork out over £38.oo on DSS. Next problem the right nuts and bolts to fit it.
I brake for animals!
1978 CB400F2 named Elen.

Offline Oddjob

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Re: Exhausting mystery.
« Reply #10 on: August 16, 2026, 08:09:06 PM »
Usually M8 nuts and bolts George.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Online exvalvesetdabbler

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Re: Exhausting mystery.
« Reply #11 on: August 16, 2026, 08:17:08 PM »
Honda 95011-61000 Rubber A for the rubber stopper that attaches to the exhaust itself.
Regards
Dave

Offline Athame57

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Re: Exhausting mystery.
« Reply #12 on: August 16, 2026, 08:19:06 PM »
Usually M8 nuts and bolts George.
Thanks for this, all I need now is the lengths.  ;) I'm glad this job is marked down for the mid term, gotta save some dosh to do it!  ;D
I brake for animals!
1978 CB400F2 named Elen.

Online exvalvesetdabbler

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Re: Exhausting mystery.
« Reply #13 on: August 16, 2026, 08:19:31 PM »
That's why they might be rare, they get tossed with the old muffler when folk fit something different.

Offline Athame57

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Re: Exhausting mystery.
« Reply #14 on: August 16, 2026, 08:22:59 PM »
That's why they might be rare, they get tossed with the old muffler when folk fit something different.
Someone should muffle these old tossers!  ;D
I brake for animals!
1978 CB400F2 named Elen.