Author Topic: CB400F airbox rubber sealant  (Read 456 times)

Offline AshimotoK0

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CB400F airbox rubber sealant
« on: February 09, 2024, 09:30:21 AM »
Any tips on the type of sealer/mastic to use between the the 400F plastic airbox and the rubber inlets/large oval rubber seal.

In the past I suspect I used this black coloured AS1701 silicone sealant. .. however the tube I have is very old and  has gone solid and it's now £50 a tube.

https://uk.farnell.com/acc-silicones/as1701-310ml/sealant-silicone-neutral-cure/dp/8497524

I found I do have some of this black polyurethane 2-part sealant (out of date but still usable) and I will use this unless anyone can suggest something more suitable.

https://uk.rs-online.com/web/p/potting-compounds/1608497


I
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline McCabe-Thiele (Ted)

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Re: CB400F airbox rubber sealant
« Reply #1 on: February 09, 2024, 09:37:36 AM »
Would normal Black Silicone Bathroom Sealant do the trick or does it need to be none hardening?
Easy enough to remove last tube I bought was less than £5.00.
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Offline magpie114

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CB400F airbox rubber sealant
« Reply #2 on: February 09, 2024, 10:38:41 AM »
Just done this myself using Threebond black RTV silicone sealant.


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« Last Edit: February 09, 2024, 10:55:26 AM by magpie114 »
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Offline Bryanj

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Re: CB400F airbox rubber sealant
« Reply #3 on: February 09, 2024, 01:13:49 PM »
Sikeflex, spelling could well be wrong mate

Offline AshimotoK0

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Re: CB400F airbox rubber sealant
« Reply #4 on: February 09, 2024, 02:05:39 PM »
I went with the polyurethane material in the end. Supposed to be pretty chemical resistant. The Threebond sounds OK though. It's probably close to the stuff I had in my 1st link.

I don't reckon that the original sealant was silicone ... possibly not in use so much then as an adhesive. From memory Hermetite orange RTV came out in the mid 70's ... you know the dreaded stuff that blocked tiny oil feed holes/ galleries when too much was used.
« Last Edit: February 09, 2024, 02:13:26 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline McCabe-Thiele (Ted)

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Re: CB400F airbox rubber sealant
« Reply #5 on: February 09, 2024, 02:17:58 PM »
Memories of Brown-Black Wellseal also spring to mind.
Local rumour was it was developed by RR Aero Division.
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Offline Moorey

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Re: CB400F airbox rubber sealant
« Reply #6 on: February 09, 2024, 07:17:44 PM »


     Black Sikaflex EBT

     Too late i guess.

Offline AshimotoK0

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Re: CB400F airbox rubber sealant
« Reply #7 on: February 09, 2024, 10:27:38 PM »


     Black Sikaflex EBT

     Too late i guess.

Seem that's polyurethane too but one part.
The stuff I used (2-part) seems to have worked really well anyway and is semi-flexible after curing.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Athame57

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Re: CB400F airbox rubber sealant
« Reply #8 on: February 09, 2024, 10:55:58 PM »
I'm not sure I know what is going on here, I've never used a sealant before. Are they not airtight enough on their own or something?
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Offline Bryanj

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Re: CB400F airbox rubber sealant
« Reply #9 on: February 10, 2024, 08:03:12 AM »
They originaly have some sort of glue/sealant in the groove

Offline Matt_Harrington

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Re: CB400F airbox rubber sealant
« Reply #10 on: February 10, 2024, 08:28:49 AM »
I'm not sure I know what is going on here, I've never used a sealant before. Are they not airtight enough on their own or something?

I'm with you on that one!
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Offline AshimotoK0

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Re: CB400F airbox rubber sealant
« Reply #11 on: February 10, 2024, 09:48:05 AM »
Yes the original arrangement definitely had so kind of sealant on the rubbers and I don't think they would seal perfectly without it. The carb inlet ones also need to align with the raised dot on the airbox.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

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Re: CB400F airbox rubber sealant
« Reply #12 on: February 10, 2024, 01:49:33 PM »
Here it is after bonding with the 2-part Polyurethane

Had difficulty fitting the two centre rubbers to the carb intakes, despite  warming up the still fairly pliable rubbers. This is because the plastic collector box housing flexes ...... so came up with this 'tool'  to push from the inside of the air filter frame. Will see how it goes  :)

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“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

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Re: CB400F airbox rubber sealant
« Reply #13 on: February 10, 2024, 11:06:54 PM »
I'm not sure I know what is going on here, I've never used a sealant before. Are they not airtight enough on their own or something?

I'm with you on that one!

You can see sealant used on this picture of a NOS air-box assembly.


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“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

 

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