Hey there, If you go to Harbor Freight, you can buy an entire set of O-rings of various sizes, one in metric and another in ASE. Both entire sets are cheaper than buying individual ones from a parts store.

 

My concern would be the ethanol resistance of a Harbor Freight o-ring - and the references I've come across to the "non-standard" size - diameter and cross section of the Honda parts. The link provide at least claims to be ethanol tolerant - and the prices are MUCH better than for an "official" Honda part. Anyone know what size thes o-rings actually are - or what size will work to make the needed seal?

 

I've never had any issue with the HF o-rings. They are rated for fuel. If you think about it, unless they changed the o-rings to specifically account for ethanol, the OEM o-rings probably aren't any better because your bike was built and spec'd prior to ethanol usage.

I don't know the exact size for your t-fittings, I have always fitted them till they were tight yet but would fit and go from there. Never really had an issue.
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Be mindful, that Honda is known to use weird metric sizes for o-rings. Don't ask me how I know. I had the same issue and ended up paying the price of doing the job again.

 

And that is what I am trying to avoid - some of my research has indicated the same thing - hence my question for the group as to the size of the "correct" o-rings.

That said, Harbor Freight certainly isn't expensive and other than the time lost, may be worth a shot.

 

Had the same sizing issue with o-rings for the coolant pipes on my bike. Honda used 2.5 mm x 18, if I remember right

For fuel look for viton and avoid buna material.

My research shows that 16101-mm5-505 is a full gasket set for the carb, not just the o-ring

https://www.bikebandit.com/oem-parts...151648#sch1494

I think you're going to have to pull one and put the calipers to it

 

To bring this to some sort of a conclusion - after much research, I found a reference to a similar problem in a list for CB750's. One of their folks said they had gotten an 8 x 2 mm o-ring at NAPA and said it solved their problem. Well, NAPA being just down the rod, I tried it. The ID of the O-ring is a bit bigger than the actual groove of the tee - but it was a snug fit into the carb body - and more importantly, it didn't leak!! Carbs are back on the bike and it is now holding fuel!! A few minor things to attend to, and it should be back on the road.

While researching the issue, I did come across this site - Orings and More | Affordable and Quality Gaskets and Seals - they have all sorts of kinds and sizes of o-rings. I ordered some on either side of 8 x 2 mm just in case. You can't beat getting 10 to 25 for a dollar - and the shipping was only $3.00. If the problem reccurs, I've got a lot to work with. I did look at the Harbor Freight assortments, but unless there is one I didn't see, none of them went down to the size needed.

 

Are bad too.
Thanks for the post and information.
I took it a step further and used the search feature on the O rings and more site, using the original honda part #, they cross reference to this