[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=218003#p218003:1kzc8uhx said:
pidjones » Fri Jun 19, 2020 11:07 am[/url]":1kzc8uhx]
I've used o-rings for close over 50 years. Viton is great for ozone resistance and fantastic for temperature (up to 200 C!) resistance. Pretty good for UV and radiation resistance. BUT it is not great at resilience. It "takes a set" when compressed and doesn't rebound as well as Buna-N. So, in our motorcycle use it is primarily good for higher temperature applications (of which there are none in the carbs over Buna-N's 100 C upper limit). For vacuum system use, I really prefer Buna-N (Nitrile) strongly unless the system is to be baked. For the rest of the machine it would be Ok for the water system except there are a lot of joints in it that cycle compression with temperature, so I'd stick with Buna-N there. I see no advantage to Viton in the float valve tips, but it seems that other than Honda's the only quality ones are Viton. Doesn't mea I wouldn't use a Viton o-ring if I have them on-hand but if there is equal quality and both available I'd prefer Buna-N. That said, I use Randakk petcock repair parts because they are the best I've seen so far. Very nicely molded. The o-rings in their kits are properly sized and look to be quality. Still, if the same Buna-N o-ring is available, I'd prefer it.
BTW, many rebuilders recommend to not use the replacement jets in favor of using the originals after proper cleaning. I agree with that (as long as the originals are not damaged).