Correct O-ring material for carbs

I've never had to buy the o-ring seperatly before, so I have no idea what material I need to buy. I know viton is probably the best, but spendy. I'm wondering if nitrile orings would hold up for fuel rails and such.

thanks,
Sarge

Yep, nitrile/Buna-N WILL work but they've gotta be compounded specifically for use in fuel systems....especially with all the alcohols in the horse-piss they're selling us as gas these days.
Viton is THE way to go and it's not THAT much more than nitrile unless someone is trying to bend you over. If possible (and you haven't done this already) try to find an industrial supply place in your area that handles metric orings. Parker-Hanifin is a HUGE manufacturer of orings and has distributors everywhere in the civilized world. You can go to their website and download the particular catalogue you need and also check for distributors in your area. Last time I checked, their website wasn't exactly user-friendly but you CAN poke around and get to where you want to go with a little work. Sometimes paper catalogues are just better.....

Thanks, I was looking at oring assortments on ebay, there is a viton 500 piece but they want like $119 for it compared to $15-$20 for nitrile. I'm going to look at the company you recommended before I buy any. I'd hate to spend all of the time and effort rebuilding carbs only to have the orings fail....especially if they are customers carbs.

Sarge

Yeah, I wouldn't mess with the nitrile. Definitely Viton.

Try this place for some individual o-rings. The standard industrial sizes won't cover all the orings in carbs, so this place is good because it has measurements. Plus it was nice that they let me order a measly 3 or 4 orings a couple years ago.
www.crc2onlinecatalog.com/gl_carb_parts.htm

snorules wrote:

Thanks, I was looking at oring assortments on ebay, there is a viton 500 piece but they want like $119 for it compared to $15-$20 for nitrile.

A kind young man who works at the local Kawasaki stealership here was the guy who warned me when I tried to order an O ring from them since they cost about $12 each. Seriously, $12 each for an O ring.

he said go to the phone book and look up plumbing supply and you will find O ring suppliers. I did, and went to buy O rings. They have every size (metric and English) in every material. I needed about eight different O rings and he found them in Viton.

The capper was when he told me that since it was under $20 he wasn't going to write up a bill, he was just going to "sample" them to me..... sometimes karma gives you a break.:laugh:

McMaster-Carr sells a wide range of O-rings, both metric and dash-numbered sizes. www.mcmaster.com/

Buna-N is perfectly suitable for use in carburetors. Viton O-rings are only required for high temperature applications like inside the engine. I've been using Buna-N O-rings in my carbs for a number of years with good results.

Thanks for all the replies. I found a viton assortment on ebay for a reasonable price. The ones I was looking at that were super expensive were for scuba use. probably the same thing, but as soon as you slap a specialized application on them (scuba, aviation), the price quazillionuples.

Sarge

The GS Suzuki guys buy TONS of Mikuni kits from cycleorings.com with excellent results. www.cycleorings.com/

All the carb kit O-rings are Buna-N, and the intake boot O-rings are Viton.

I don't think there is anything wrong with full Viton O-rings in the carbs but I think it's overkill for the application.

According to Marco Rubber, Buna N (nitrite, nitrile) gets a similar rating as urethane for gasoline. Urethane fuel line degrades rather quickly, in my experience, with the oxygenated fuels.

They rate Viton one step higher than Buna N in their rating scheme (scale 1 to 5, 1 being best). They rate Viton ETP as one step higher than regular Viton, but I haven't seen Viton ETP advertised by my o-ring sources.

Viton ETP gets a 1
Viton gets a 2
Buna N (nitrite, nitrile) gets a 3
Urethane gets a 3 (but it's on a different chart)

Thanks for the chart, very interesting

Sarge