Years ago, I bought one of the first hand-modified Ritchey RTO engines. I sent in a used MT-12 and got back a modded one. Ran like the devil, but what eventually happened is that the carbon-fiber insulator sleeve on the lower neck of the slide carb split and came apart. Now the carb is too small to fit in the crankcase, of course. I wish to use the carb and would like to know either where I can get a replacement insulator, or, worse-case scenario, can get a replacement carburetor.
FWIW this carb has a machined and polished bell-mouthed throat, looks like a little velocity stack.