Not to much to say about this beyond what the title says, but if you want to run Mikuni TM28’s on your RD350 then it’s ideal to modify the TM28’s spigot so it fits the stock manifold properly. Air leaks on two strokes are never fun, and it’s always better to be safe than sorry! This process modifies the carb by machining the TM28 spigot and then pressing on a new spigot that is the proper O.D. to fit the RD350 manifolds. Good stuff! The process costs $65 plus shipping.
You can find this new mod in the custom machining section.