- Are the o-rings for the t-tubes included with the Carb kits? Depends on what kit you get.
- Are the o-rings a standard size that can be purchased separately? Yes, the fuel T rings are 2mm x 8mm. I find 1.9 x 7.8 fits a little more snug.
- Are the inner and outer o-rings different sizes? No.
Fuel bowl drain plug.
- The head of the plug is stripped. Are replacements available? Some places make repops. If it's stripped, you should first see if you can get it out. Use vice grips, you are planning on replacing it anyways right? The reason is, if it is stuck in there or breaks off, you need a new bowl probably too unless you are lucky with an extractor.
If you want all the stuff you mentioned pm me and I can help you out with it.