400 four main jet o ring

[exvalvesetdabbler]

I'm trying to get some o rings for the carb internals and have managed to size most of them except for the push fit main jet. I have crawled the net on and off over the last few days and not come up with anything convincing.  4.2 x 1.1  or 3.2 x 1.2 seems popular.  But looking at the measurements, neither  size is going to be a very snug fit.

I'd rather buy a bag full from a reputable source as opposed to just buying four at silly prices + postage.

I don't like reusing rings and don't see it as  sustainable to keep buying carb kits just for the sake of one o ring.  In other words it's a PITA having to buy kits just to pop out the emulsion tubes and ensure they are clear and free of corrosion.

Does any one know the right size?

Regards
Dave

[Athame57]

I think you need to pm Nurse Julie for them! 

[exvalvesetdabbler]

I just need the size, I'm amazed that even now these things are still closely guarded secrets.


Regards
Dave

[Oddjob]

Assuming the jets are the same as the 500/550/750, which I think is a reasonable assumption, then according to the genuine Honda parts book they are 4.2x1.1.

[exvalvesetdabbler]

Thanks Ken,


That's what I'm finding, just seems like they're going to be a loose fit.

Regards
Dave

[ozzybud]

These are a perfect proven fit.1.2mmx3.5mm buna n70
Qty 36 was under $8.00 us

[McCabe-Thiele (Ted)]

According to Google serach

The main jet O-ring for the Honda CB400/4 is a 4.2mm x 1.1mm O-ring. This is the correct size for the secondary main jets in the Keihin carburetors used on this model, and it is also the size for many other Honda motorcycles from that era, such as the CB350, CB500, and CB550.

Dimensions: \(4.2mm\) (inner diameter) x \(1.1mm\) (cross-section).

Part Number:OEM part number 91301-426-010.

[Bryanj]

Yup, just try buying them anywhere except Honda, or Julied who sells full carb sets for not a lot

[McCabe-Thiele (Ted)]

Fowlers have them in stock - not cheap.

www.fowlersparts.co.uk/search/part/91301-426-010

[AshimotoK0]

Fowlers have them in stock - not cheap.

www.fowlersparts.co.uk/search/part/91301-426-010

That must fit the main jet of a rather large marine engine Ted 

[McCabe-Thiele (Ted)]

That's weird, the part number on Google must be wrong.
 My excuse is I had a bout of insomnia hence the post time.

[ST1100]

According to Google serach
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Part Number:OEM part number 91301-426-010.

Never trusted Google... comes back as 'O-ring oil-bore cylinder head'...
https://www.cmsnl.com/products/o-ring-49x25_91301426010/

this seems to be it 16177-551-004
https://www.cmsnl.com/honda-cb350-japan_model50676/42x11-o-ring_16177551004/

[ozzybud]

According to Google serach

The main jet O-ring for the Honda CB400/4 is a 4.2mm x 1.1mm O-ring. This is the correct size for the secondary main jets in the Keihin carburetors used on this model, and it is also the size for many other Honda motorcycles from that era, such as the CB350, CB500, and CB550.

Dimensions: \(4.2mm\) (inner diameter) x \(1.1mm\) (cross-section).

Part Number:OEM part number 91301-426-010.

Please don't trust google for anything these days especially for motorcycle or medical advice.
The o-rings i posted above are the correct material and fit. They pop in snugly.
All of the kits you can get in the states do not have the correct main jet o-ring.
I have been using these for years and sharing with friends. If you were close I would gladly send you a set fir free.

[McCabe-Thiele (Ted)]

 

 I blame AI as well.   

[Oddjob]

Is that the correct material Ozzybud?

Says NBR on the packaging and if memory serves that’s nitrile, which is not recommended for today’s fuels containing ethanol. Surely Viton or FKM would be a much better choice?

AFAICR the original orings were nitrile and so I’d avoid replacing with genuine parts for this application as the same problem will just reoccur. Unless Honda have changed the material at a later date to allow for this.