Carb O-ring sizes and source?

[R65Singh]

Hello Gang;
I am trying to figure out the exact sizes of the O-rings used in 32mm Bing carbs.  For some reason, metric o-rings are so hard to find at local automotive stores including Napa, Lordco etc.  I came up with the following sizes and please correct me if wrong.

Main Jet            ID 8mm   OD 12mm  CS 2mm
Throttle shaft         6              10             2
Choke shaft           5                8             1.5
Idle and mix           not sure

Does anyone knows a good source as these are almost used every time we open up the carbs.  Would be nice to order in bulk rather than paying $2 for each o-ring.  Check this site out
http://www.oringsusa.com/
Please feel free to add more sources.  Thanks

[Red_Hen]

I'd suggest contacting Bing direct or getting parts from Motobins UK.

[montmil]

I have purchased two cases of metric o-rings, all in various sizes from small tiny to el biggo. They repaired my .177 squirrel, uh... air rifle but none, nada, zero match up with the Bings. Buy a rebuild set of rings from Motobins as I did. Inexpensive, they fit and Royal Air Mail for the small package is economical.

Monte

[bruce_launceston]

I have found that the standard black idle jet 'O' rings do not last long and can make it difficult to remove the jets.
I am running a pair of green airconditioning 'O'rings on them that I was told would be more resistant to fuel.
They have only been in a week so time will tell.
As to the size they are the smallest ones in the big box assortment that I had to choose from. They were slightly thinner than the smallest black ones available and looked like they would be a better fit.

Take your jets and shafts into a parts supplier or a service department and go through their assortment untill you find the right sizes, you will probably only pay cents for them.

[Barry]

I have hundreds of O rings in the usual kits both metric and imperial and I've never managed to find one to properly match the main jet holder. Overall diameter is easy but they are always too thin.

Here's a link to Anton Largiader's site that lists some sizes.

Perhaps next time one of us replaces the O rings with the genuine article they could measure them accurately and either confirm Anton's list or write one up and post it in the FAQ section.  It's such a common issue it would one of the most useful things in there.

I
http://www.largiader.com/tech/carbs/

[Milrog]

Hi Everyone. I am the new guy.

I had same problem trying to source O rings for the idle jets in the 32mm Bing. Gasmate Camp Stove control spindles P/N GMORN-1 are the right size (6mm OD 3mm ID and 1.5mm CS) they seem to work just fine.  

[Barry]

The things I do in my lunch break.

Here's the nearest standard O ring sizes both Metric and Imperial.

The metric ISO 006 is a good match for the mixture screws and the ISO 011 is OK at a stretch for the main jet holder. Nearest size for the enricher spindle is the Imperial sized 008. They are a bit tight but I think that's the size I have used successfully.  You need as a minimum spec NBR (Nitrile) rubber which is what most of the decent sets are.

The throttle shaft O rings have no match that is close enough so I wouldn't  even think about cheaping out on those.

[tvrla]

I also noticed o-rings tended to be damaged once the jet was removed. That got me wondering if perhaps the jet was causing that.

One thing I noticed was that o-rings tended to split legth-wise, which really got me thinking the jet had something to do with it. I got pretty good at spotting a compromised o-ring even though the split normally hid from view in the groove.

Upon close inspection, I noticed some very sharp edges where those O-rings live - the idle jet and mixture screw especially. My conclusion was that while screwing the jet into position the sharp edges would slice the o-ring which wants to remain stationary due to it's contact in the bore.

The solution was to carefully chamfer those edges - round them a bit - and then hit them with the polishing wheel. I used a small fine rat tail file that was larger than the groove, hitting it only lightly. And for the mixture screw where the o-ring needs to slide over the head of the screw, I rounded the sharp edges there too and polished.

Also, be sure to grease the o-rings, leaving but a molecular layer that makes them look shiny in apperarance. This will also help them slide into position without binding.

Ever since incorporating these changes I've had no more damaged o-rings upon disassembly and can re-use them over and over.