Carburetor Crossover O-Ring Size (1978 CX500)

jefish said:

Does anybody know if the O-Rings which seal the crossover tube into carburetor bodies are a readily available size? I replaced them last year when I rebuilt the carbs and wasn't terribly happy with the quality of the fit, but they sealed and didn't present a problem until a couple days ago when I noticed some fuel on the ground after a ride.

I'm really hoping they're a size that I might be able to get at a hardware store because I'm a bit reticent to spend $25 for a bespoke o-ring that I know cost a nickle to make.

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bahn88 said:

See list attached

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jefish said:

Awesome. I just ordered them on McMaster. Now I just need to find a home for the other 98 O-rings in the package...

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danroy323 said:

But then all the better quality carb kits use Viton orings. Viton resists heat better too. The 10 pack of Viton orings is cheaper than the 100 pack of Buna (nitrile) ones. As I don't plan on rebuilding 5 sets much less 50 sets of carbs, I now have a lifetime supply, I have the peace of mind that the Viton ones are good and I saved a few pennies.

Side notes:

Last year I resealed the oil injection pump on my Suzuki TC90 2 stroke with Buna orings, I had the right sizes on hand. After a short time it developped a leak. The orings had gotten really soft. Resealed with Viton orings and no more leaks for now. I know it is injection oil and nos gas but still it is my experience that Viton stands up better than Buna.

I work in plastic injection mold making, we use Viton orings everywhere even if we're most of the time sealing water or air lines, we see much better durability with Viton.

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bahn88 said:

The chart posted had nitrile as severely affected by gasoline..

Fully agree if its a oring you replace periodically.. Viton...i even use V in the final drive splines as black greases with moly Could tend to be more aggressive than a general lithium soap grease....few dollars yearly not a issue.

BTW...Worth remembering theres different grades of nitrile...so more resistant than others .
But unless this is stated...the resistance a bit of an unknown..

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jefish said:

That's sorta what I was thinking. I got a bag of 100 for under $15 after shipping from McMaster. Considering that I'll probably be servicing the Carbs every couple of years, I'm probably going to be long dead before I run out of replacements.

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