West 50 V1 Engine Queston
My West 50 runs with the carb all the way open, it needs to. I'm at about 1.5 turns on my needle I believe as well. Make sure your carb is tight and on straight and seated properly, not sucking air from somewhere it shouldn't be. My first West 50 wouldn't run past half throttle either, but that was a bad connecting rod that was slapping when it shouldn't have been. It didn't last long, it was one of very few bad engines and weston UK was phenominal in customer service.
But it should run with the carb wide open, all engines should. Check tightness of all the bolts as well, head, backplate, header, make sure you have no more than a 1/16" gap between the header and pipe. Also make sure your prop is good and balanced, past half throttle if it's out of whack it may just be foaming the fuel to much to run.