This part is apparently not available as the piston guide is considered part of the carb body. However, they need to be replaced. What is a suitable replacement? The rings aren't really o-rings, but have a rectangular cross-section like a garden hose gasket. Any ideas?
The rebuild kit from partsnmore has them. The ones with the kit are just standard round o-rings. If I were you I'd take my carb body to the hardware store and look for a replacment that fits in the cutout in the carb body.
Although its a contradiction in terms, O rings that are recta-linear in section are termed square-cut O rings. They are made to industry standard sizes. Try this link
http://www.epm.com/square_info.htm
Industry standard sizes don't seem to be close to the one good o-ring that I have. I guess I'll find the nearest size and hope for the best....
You may be able to buy a minimum length of material in the required cross-sectional sizes, if so you can super-glue it together to form a ring. We do it all the time in industry. Multiply the ID of the required ring size by 3.14 then add the width of the material to give the length of material required.
ive replaced all my Orings with Round style Orings, have not had an issue. ive matched them from an autopart store's assorted box.
I got an o-ring by going to a bike shop and finding one that fit. No problems as of yet.