Author Topic: '77 CB400F fuel fill "door" noise  (Read 1236 times)

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Offline mattsz

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'77 CB400F fuel fill "door" noise
« on: September 04, 2020, 12:46:11 PM »
Anyone cursed with the hideous hinged fuel tank fill cover - like on my '77 CB400F and possibly other models... I've just got my bike up and running, and the door vibrates at certain RPMs and makes a god-awful racket!  Nothing looks bent or out of shape, but the door contacts the tank along its right side and stands proud on its left.

Anyone have any hints for quieting it down?  Some kind of gasket-like padding, or perhaps an attachment trick?

Offline Bodi

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Re: '77 CB400F fuel fill "door" noise
« Reply #1 on: September 04, 2020, 03:42:25 PM »
It should have a rubber ring that wraps around, locks into the metal flange with a groove.

Offline mattsz

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Re: '77 CB400F fuel fill "door" noise
« Reply #2 on: September 04, 2020, 05:33:02 PM »
It should have a rubber ring that wraps around, locks into the metal flange with a groove.

Damn, look at that, you're right!  I have a "multi" parts book which shows it - they call it "packing."  Yet another unobtainium part...  :(

I wonder what kind of U-cross-sectioned rubber or material I could use instead...

Offline Bodi

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Re: '77 CB400F fuel fill "door" noise
« Reply #3 on: September 05, 2020, 06:00:11 AM »
If you find something that works, let me know. Mine is disintegrating.

Offline mattsz

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Re: '77 CB400F fuel fill "door" noise
« Reply #4 on: September 05, 2020, 06:08:02 AM »
I will.  I know there's some sort of strip that sometimes finds its way onto the lower "pinch-welds" of fuel tanks, but I think those are usually hard "chrome" plastic?

I do have some thin, tape-like adhesive-backed neoprene, which I suppose I could cut into a narrow strip and apply it, folded over, around the perimeter of the door.  But it's much softer and not nearly as sturdy as rubber, no idea how well it would work or how long it would last, especially if it gets wet or exposed to sunlight long-term...

Offline robvangulik

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Re: '77 CB400F fuel fill "door" noise
« Reply #5 on: September 05, 2020, 08:31:46 AM »
Fuel line, slit lengthwise?

Offline mattsz

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Re: '77 CB400F fuel fill "door" noise
« Reply #6 on: September 05, 2020, 09:08:43 AM »
Fuel line, slit lengthwise?

Good idea!  Or some similar tubing - it would have to be a pretty small diameter...

Offline bryanj

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Re: '77 CB400F fuel fill "door" noise
« Reply #7 on: September 05, 2020, 11:16:06 PM »
Vac advance pipe on a car?
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline mattsz

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Re: '77 CB400F fuel fill "door" noise
« Reply #8 on: September 06, 2020, 03:06:41 AM »
Black tubing:

Viton, 1mm ID, 3mm OD, from Australia - not cheap:
https://www.ebay.com/itm/Viton-Rubber-Tubing-Tube-Hose-Tubing-Tube-ID-from-1mm-to-16mm/151911299977?hash=item235e9e7b89:g:BfsAAOSwNphWaSgL


Silicone, 0.5mm ID, 1mm OD
             1.0mm ID, 2mm OD
             1.5mm ID, 2.5mm OD
from a modeler's supplier in the UK - not too expensive.  Difficult to attach?
https://www.ebay.com/itm/Miniature-Silicone-Fuel-Line-Tube-1mm-2mm-2-5mm-1-12-Tamiya-1-8-Pocher-1m/141951682927?hash=item210cfac96f:g:JukAAOSw-RRXBY34