Carb O-ring Sizes

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H D
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Carb O-ring Sizes

Post by H D » Tue Jul 03, 2012 2:43 pm

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!

Maelstrom
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Post by Maelstrom » Sat Mar 23, 2013 12:53 pm

The jet housing o-ring is not 10.0 x 1.5 it is 10.3 x 1.35. Mikuni part number is N138198.
The thickness of this o-ring has to be precise because it is compressed as the emulsion tube is pulled down by the tightening of the holding screw. I have never tried an o-ring with a cross section of 1.5mm nor would I want to. The amount of pressure required to pull the slide housing into alignment with the throat is already significant without making it worse. To see an illustrated guide to what I am referring to please see http://www.litetek.co/Guide_MikuniBDST_ ... gAssy.html These Yamaha carbs use the same o-ring, slide housing etc as the Suzuki. It is important that you understand the function and fitment of the part when considering an alternative replacement, especially an alternative size.

I know you mean well by advising forum members to use something that is "close". In most cases it won't do any harm, but in this case it can.
cheers
Blair
Carb seal kits in viton & other parts
https://litetek.co


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