Can anyone identify this carb washer (79' Cx500) ?

Correctly servicing the Carburettors on these bikes is paramount to good running and fuel economy so any work done will pay back in better mileage :)
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Can anyone identify this carb washer (79' Cx500) ?

Postby <3d0b.html?mode=viewprofile&u=774">Herbert Chapman » Fri Aug 06, 2010 10:32 pm

Not a quiz unfortunately. Having given my carbs a good soak overnight I was squirting away with WD40 when this little washer fell out of somewhere into my hand. Very lucky it didn't just fall to ground without me noticing.

It's the one with the arrow pointing to it naturally. As you can see it's more tubular shaped than the usual O-rings and is very small. The pic I've posted does not show the washers relative to each other in size. It is about the same size as the small O-ring that sits under the Air Cutoff valve cover.

Image
CX500A '79
Yam TDM 900 '03
Leafy South Bucks
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby Gman » Sat Aug 07, 2010 9:30 am

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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby <3d0b.html?mode=viewprofile&u=774">Herbert Chapman » Sat Aug 07, 2010 10:48 am

Thanks Boss,

I think I may have answered my own question when I asked it - the same size as the washer under the cut-off diaphragm cover - I reckon it is that very washer :oops:
CX500A '79
Yam TDM 900 '03
Leafy South Bucks
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby Gman » Sat Aug 07, 2010 12:35 pm

Glad you found it.Pictures can be deceptive.The one used in the Air-cut-offs normally has a bevelled edge on one side and this is fitted face down so the flat edge is presented to the cover.

Note:The Air-cut-offs can be bypassed by making a small rubber circle punched out of an old tyre inner tube
viewtopic.php?f=10&t=256

(Buy a cheap set of punches off Ebay)


and placed in that hole with no ill effects.All you do is add a little twist to the idle mixture screws if needed to make the mixture a little richer.
When Honda made these bikes they did an incredible job of making the carburettor system and exhaust system very fuel efficient but this also meant that they are a ,"Lean Burn" engine so any small fault anywhere makes the fuel delivery system very picky.The Air-Cut-offs make the fuel delivery a little richer when throttling off to avoid ,"Popping" when throttling down but this is easily over-come by the above small adjustment and bypass.
The CX500 engines were leaps and bounds ahead on many of the competition's engines at the time of release in many aspects many of which are now incorporated in their modern machines with refinements.
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby <3d0b.html?mode=viewprofile&u=774">Herbert Chapman » Sat Aug 07, 2010 7:38 pm

Not really sure what you mean though I seem to remember reading a more detailed piece by yourself over on CC explaining step-wise how to implement this mod. You don't have a link to it do you? The link you've placed in your reply is to your home made gasket advisor.

Many thanks
CX500A '79
Yam TDM 900 '03
Leafy South Bucks
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby Gman » Sat Aug 07, 2010 8:33 pm

Basically you just replace the small O-ring with a solid one/piece of rubber but leave all the other gubbins in place.The reason I posted the link was I used one of the small leather punches and a piece of old inner tube to make the small solid O-ring.

I think it was the smallest one of the set e.g 3mm,

http://cgi.ebay.co.uk/6-Pc-METRIC-HOLLO ... 23079e4ac0

These are an absolute bargain and then a little dab of superglue to hold it in place.
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby <3d0b.html?mode=viewprofile&u=774">Herbert Chapman » Sun Aug 08, 2010 9:51 am

Does this mean then that the vacuum which is induced on throttle off at high revs, never gets to activate the cut-off?
CX500A '79
Yam TDM 900 '03
Leafy South Bucks
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Re: Can anyone identify this carb washer (79' Cx500) ?

Postby Gman » Sun Aug 08, 2010 9:09 pm

Herbert Chapman wrote:Does this mean then that the vacuum which is induced on throttle off at high revs, never gets to activate the cut-off?


Correct.

You can see from a Google search,

http://www.google.co.uk/webhp?hl=en#hl= ... 8f9dc97a30

It's done on all sorts of bikes with these devices.I can't remember which of my bikes I've done it on which in itself shows that it works as they both have no problems :)
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