Do you have the old ones? If you do it is easy to figure out what you need if you can measure the size of the bore (OD) and the cross section diameter of the o-ring. Look up local hydraulic pneumatic repair in your area and carry in the old ones so they can match it up. Also Harbor freight has an o-ring kit for a few bucks that might have what you need. It has been my experience that often Honda will list sizes like 25.4mm only to find that is in fact american size one inch. I think there is a really good chance FYI an o-ring made of viton or nitrile are compatible with gasoline and common.
Using JD's info I was able to find the O-rings you need are JIS P3. The dimensions are 1.9 mm x 2.8 mm. ...If you cross that to American it is 1/8" ID x 1/4" OD x 1/16" cross section. It would have a part number of -006 (pronounced "dash 006") Sometimes refereed to as A006.
Just went out to my shop and found my Harbor freight kit included 20 of them. Here is a link and if you look close at the second image top row you can read 1/8 X 1/16. These are nitrile and good for gasoline. All for $5.00.