Group buy of the rare o-rings needed for the Zenith Carbs that are NOT included in any gasket kit

deQuincey

deQuincey

Quousque tandem...?
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Hi I have been enjoying the company of two sets of zenith inat carbs during last holidays

I have been using new spare set of gaskets, washers, membranes, rings, and so on

but there are three seals that are not available or they might be not appropriate quality (at least the material used is unknown)

these are:

1- the small o-ring that seals the conection of the two sides of the volume that encloses the round membrane, see here:

20180110_205855.jpg

this seal is usually flat due to heat cycles and ageing, so if you do not have a way to replace it and if you use the same one, most likely you wont have a perfect seal and your max acceleration will not reach the value it should

20180110_205939.jpg

this is a fresh new seal, it protrudes from the surface thus it will seal perfectly

2- the cutoff valve seal that goes in the small cup

20180110_210237.jpg


i have never seen spares for this one, same as others it suffers heat cycles and deteriorates losing its function, usually cracks and dissapears
i can not find spares for this, but i have successfully replaced it with a pile of 3 o-rings

3- the o-ring seal the seals the iddle screw in US type carbs,

20180110_210744.jpg


if this seal is worn, the iddle screw will rotate and you will lose the tuning and air will come in through it
 
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my point is, that you can find o-rings of normal quality, but when it comes to fuel environments you know usual rubber will deteriorate quickly and be destroyed,

The rubber quality to use is NBR

I have a source for NBR quality o-rings, they usually accepted small orders of 2 or 4 units, but now they surprised me with a minimum 20 euro order

it is an small ammount of money, but i feel stupid buying 20 seals when i need only 2

so if anyone is interested i can make a small list and offer the prices and postage costs here

to make things as simple as possible i propose to organize it in lots for 2 carbs, so every lot will consist of:

2 small o-rings for round membrane container
6 medium o-rings for cut-off valves
2 medium o-rings for the iddle screw

guess each o-ring between 1,8 to 2 euro

i make my order tomorrow, so if there is any interest just do tell asap

regards
 
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deQuincey said:
so if anyone is interested i can make a small list and offer the prices and postage costs here

to make things as simple as possible i propose to organize it in lots for 2 carbs, so every lot will consist of:

2 small o-rings for round membrane container
4 medium o-rings for cut-off valves
2 medium o-rings for the iddle screw

guess each o-ring between 1,8 to 2 euro
i make my order tomorrow, so if there is any interest just do tell asap

regards
Click to expand...

I'm in for a set.

Thanks for sharing.
 
hi everyone, i completed one order and i am preparing a second one, but this will be the last one, so please if you are interested today, friday the 12th is the last day
thanks
 
But truth be told, in my motorcycles I just use o rings from one of those generic packs of a million. I think those are generally nitrile or nbr as you call it. Never had an issue.
In my e21 that got driven to Winnipeg in winter I use Viton for the temperature (-40) and pressure(fuel injected) characteristics and well some parts are just a pain to get to and I never want to go back. But in a carb? Viton would perhaps be over kill.

Very easy to measure o rings with a caliper and buy from our favourite place McMaster Carr.
In fact you can buy square cut EPDM rope and make your own brake cylinder o rings..or any o ring really.

The small ones like below for example for the idle jet,
are 1.6 mm thick with a 2.2 mm I.d.
Called a ..... 1.6 x 2.2
6 cents each. Or Viton is about 15 cents each.
HTH.
But yeah...the dilemma of buying in bulk, you have to give the extras away.



FC0490D6-B0B9-443F-B57E-2313EB3CEDC8.png


Ok, sorry for the thread jack...but I was just doing my dirt bikes carb and was rummaging around in the o-ring dept and this thread caught my eye...

Carry on....As you were....
 
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restart said:
Isn’t NBR another name for nitrile.
I would use Viton o-rings for gasoline.
Click to expand...

nbr means nitrile butadiene rubber (buna N)
viton is apropriate for oils and high friction so high temps, so gear box and engine seals are usually specified in viton that is much more expensive,
a pitty you didnt found this before, my costs were 14,6 euro for each complete set, plus a mistake i made in shipping costs (i quoted 5 euro and they charged me 5,6 euro) costed me almost 3euro to make this run
apologies for havent been able to find a better way to do this, thank you @restart
 
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