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SOHC.co.uk Forums => CB350/400 => Topic started by: Lobo on July 25, 2013, 08:51:03 AM

Title: CB400F Air Manifold
Post by: Lobo on July 25, 2013, 08:51:03 AM

This ones nagging me... help!

I've assembled the black air manifold rubbers (4 carb + 1 inlet) dry, ie without any type of sealant. Consequently they could never be described as air-tight, particularly the large rubber in from the Airbox.  I appreciate we're on the atmospheric side of the carbs, and rest assured that the air filter will always be clean - ie little cause for 'leaks'.... But should I disassemble (ugh) and 'fix'  or is this how it all should be? (unable to verify mixture / running at high speeds as still awaiting the tank)

All rubbers by the way, new & nicely flexible.
Cheers,

Title: Re: CB400F Air Manifold
Post by: tom400f on July 25, 2013, 09:33:37 AM

I'm sure Bryanj etc will be better placed to comment, but I would say there's a decent vacuum at that point so sealing is wise. Furthermore, my (essentially new) manifold has a gooey substance under those rubbers.

Title: Re: CB400F Air Manifold
Post by: Lobo on July 25, 2013, 09:41:58 AM

Aye, thanks Tom. Had a recurring memory of that large rubber glued in....boll..ks!

Anyone / Bryan able to suggest best goo to use? Silicon sealant? On all 5 rubbers?

Cheers,
Simon

Title: Re: CB400F Air Manifold
Post by: Bryanj on July 25, 2013, 05:01:02 PM

Never bothered with any goo there and never had a problem. the 500 had a "drain" tube open to atmosphere on the carb side of the aircleaner which always seemed a bit daft to me but worked.

Title: Re: CB400F Air Manifold
Post by: Lobo on July 26, 2013, 02:40:43 AM

Thanks Bryan, with that observation I'll give up at the first sign of difficulty in the dismantle & simply monitor the performance / plugs instead.

Cheers,
Simon