Carb O-ring Sizes

[HD]

Wondering if this could be made a sticky or similar?

Just to say that the other day I replaced all of the o-rings in my carbs. Bike runs sweet and all is well. They may not be the exact sizes but are as close as I could get. Had problems getting a good size for the two on the float but I managed it and the others aren't majorly critical anyway.

So sizes are as follows:

- 3 x 1 Mixture Screw O-Ring
- 4 x 1 Top Vacuum O-Ring
- 10 x 1.5 O-Ring between body and slide holder (white piece)
- 6.09 x 1.78 Larger O-Ring on float assembly
- 3.69 x 1.78 Smaller O-ring on float assembly

The smaller one needs a bit of lubrication to get on but then its a nice snug fit.

As a side note, you should try and get all of the o-rings in Viton (maybe not the vacuum one). It is much more resistant to petrol that normal Nitrile o-rings.

Hope that helps!

[AlanDog]

So the 3 in '3x1' dimension is for the inner or outer diameter?

I'm seeing that they can be ordered separately via amazon, but are pricey--cheaper to order OEM part it seems. I had thought maybe this harbor freight assortment might work with some of the sizes but they consider '3x1' to be a 3mm *inner* diameter--is that what I want?

http://www.harborfreight.com/225-piece-metric-nitrile-o-ring-assortment-67609.html

[HD]

Not 100% but think it was the inside diameter. That's the measurement it had on the packs. Only costed me about a tenner for the whole lot from a local place that does o-rings, bearings etc. Just type o-rings and your area into google and there will probably be surprised; I was!

[AlanDog]

Not 100% but think it was the inside diameter. That's the measurement it had on the packs. Only costed me about a tenner for the whole lot from a local place that does o-rings, bearings etc. Just type o-rings and your area into google and there will probably be surprised; I was!

No luck finding a local place with google maps, and I figure I should replace all four float needles, which would be about $50 shipped anyways, so I just ordered the rebuild kit from carbkitscapital.com (part # 48-1948).

But it occurred to me reading your email that (duh) I have the carb disassembled and I have precision calipers, I can just measure them... well, the problem (aside from precision) is that these are stretched from age, but I measure the float gaskets as being 10.3 and 8.2 mm outer diameter, which I think are the 10x1.5 and 7.5x1.5 o-rings, assuming they are a bit stretched. So it does seem like this list is the outer diameter... and so the harbor freight kit doesn't look like it will work.

[AlanDog]

Or maybe I'm wrong... http://www.oringsandmore.com lists 10x1.5 and other sizes and their descriptions say this is the inner diameter... 

They also sell the viton o-ring sizes 10x1.5, 4x1, 3x1, (in 10-packs), however they only have 8x1.5 (not 7.5x1.5) and 5.7x1.9 (not 5.5x1.5), so at least by this forum, they do not carry an exact fit for all the required o-rings. But total cost for these five 10packs is $33 shipped, so that approaches the cost of 4 rebuild kits ($33 + 50 for float needles vs. $73 for 4 rebuild kits).

but I'm not saying these sizes will fit! I have no idea. Just want to be clear.