The Bridgestone carbs were modified by shortening the inlet horn to fit inside the side covers, however I believe the internals were identical to the normal VM18.
Thanks; I'm hoping that's true for the parts that Motogary and I need. There are visible differences when comparing exploded assembly views, though. Obviously the top slide cap is different on the Bridgestone's VM17-18 (for two cables, instead of the VM18's single cable and separate lever-operated "starter plunger"), and the needle jet
looks different. The BS VM17-18 has the oil-injection port, and the float bowls (and therefore float-bowl gaskets) are different. The float, washers, springs, and (maybe) the needle valve assembly
look the same. I copied a post from (the original) member disc_valve, around 2015, which suggested that the internal thread sizes may be different than current carbs, so that could throw a wrench in the works.
Makes things exciting!