Expanding O-Rings

I recently rebuilt a set of Honda 650 carbs usimg keyster kits. The carbs where leaking around the bowl before and after rebuild. I have tried a varitey of liquid gasket stuff in conjuction with the bowl gaskets. They still leak! I probably have had the carbs off close to 20 times, no joke. I have found, repededly that the bowl gaskets seem to expand and that may be where the leaking is coming from. Is there anyway to permanently treat these gaskets so they will stop doing this?

Thanks,
Nate

I'm not sure if this is the same problem - lets see.

My carb bowls take a large O ring rather than a gasket. This O ring fits in a groove around the edge of the bowl. The O rings I got last Spring in the rebuild kits seemed to be a tad bigger/longer than the groove they were supposed to fit into. If I crammed the in and fitted the bowl the bowl would leak. I thought about cutting out a very short length and gluing the ends and this is what I will probably do next Spring - asssuming I find a good glue. How I got them to fit was to put each O ring in a separate little ziplock bag and put them in the freezer for at least 1/2 an hour. The cold makes them shrink. Take them out of the freezer one at a time. Work real fast. Fit each into the groove and screw the bowl to the carb body before they have a chance to warm up. Works for me with no leaks.

If someone can recommend a gasproof O ring glue I think it would probably be easier than freezing.

Is this similar to your problem ??

Great idea JR.Honda bond #4 only thing I have found that resists gas.

Shoey949, I have been wondering about those rebild kits for the CB650. Thanks for the tip.
It seems like the rubber used in those o-rings(gaskets) made by Keyster are made out of some low quality rubber. I have tried the float bowl gasket(o-ring) from 6 different Keyster kits for the KZ400, and all of them them did the same thing. As soon as they got in contact with fuel they expanded, and they leaked. I had to cut them and glue them together again. I also used Hermetite Golden Seal in the grooves. That cured the problem.

Post edited by: ibsen22000, at: 2005/11/07 15:25

The bowl gasket is neccesarrily an o it is more of a rectangle. However they were the right size when I put them in, but when they get wet they expand and leak. Then once they dry the process repeats itself. Ibsen, what kind of product is that? And where can I kind it? Because I have already tried "gasproof" permatex stuff and liquid electrical tape.

Thanks,
Nate

Although I did not have the gas leaking problem you describe. The O ring gaskets on my kz750 would expand when I opened up the carb bowl. It happened on roughly 40% of the times I opened the bowls up. If you throw the gasket on the hood of your car, or somewhere else in the sun, it will dry out the gas and shrink back down. Sometimes it takes as much as an hour to do. BUT!!! IF YOU WAIT TOO LONG IT WILL SHRINK BEYOND BEING ABLE TO BE PUT BACK IN!!! You WILL NOT be able to soak it in gas and get it to swell back to original size. It is just rather time specific and you have about a 3 hr window. The o-rings will work like before however.
Mark

The hermetite products are produced by Hammerite in UK. In USA you can get it here (and maybe other stores as well:

www.oldbritts.com/ob_7840.htm

Non hardening gasket jointing compound

Ideal for all kinds of joints with gaskets or for sealing metal to metal joints where a gasket is not required

Meets the requirements of the marine, electrical and general engineering industries

Temperature range -40 C to +250 C

Resistant to petrols, oil, diesel, grease, steam, water and anti-freeze

Mark, are you suggesting that I heat the gaskets and they will no longer expand when wet?

No I am not. What I am suggesting is you can reuse the oring if you let it set and evaporate the fuel out of the rubber(I just put it on the hood of the truck because it was warm and in the sun). It will shrink back down to the normal size (if you do not let is shrink too much). Like I said I did not have the prob with the fuel leaking past the oring, I just had the expanding oring and once it expanded I could not readily put it back in the bowl. It has to shrink back down to original size to be able to be reused. I do not know of anyway to stop the expansion in the first place. It only happened on some, not all the orings.
Mark

=

www.crc2onlinecatalog.com/bowl_gaskets.htm

Do you think the gaskets from this website are any better than the keysters? They look identical but that doesn't say anything for its actual compostition? If they work I wouldn't have a problem shelling out $30 at this point.

well I recently got a hunch that maybe the float levels were screwed up, even though they are platic. I determined this because to my dismay I found gasoline in my crank oil. I figured having the float level screwed up would accont for this as well as the general rich running mixture. How exactly do you measure float height, it doesn't say in the manual. Plus they are plastic floats so how would I go abotu adjusting them and how did they get changed anyway?