Re: carb switch
Physically, Almost any carb from a large 2 cylinder over 35 horsepower or three cylinder engine should fit. For example, on an old Chrysler 25 (1 1/16 venturi) I swapped a carb from a 75 horsepower engine (1 3/16 venturi) and it worked fine. No need to rejet or modify. I have also used carbs from a small bore, small carb 150 on a three cylinder 90 with no problems.
Your 50 will most likely have a carb with a 1 3/16 or a 1 5/16 venturi like a 75, 85, or 90 HP engine.
I have lots of carbs from 75 and 85 horsepower engines which in all probability would fit and work on your engine.
However, this is a case where I would never sell or even give someone a carb for replacement purposes. If by chance he had a problem and damaged the engine, I would not want to be blamed. If it were a more direct replacement like an 85 hp three carb set for a 75 hp engine, I would have no qualms.
It's all right for me because I have multiple engines and am willing to chance that I might lunch one. But for the fellow who only has his sunday engine, there should be no question of reliability.
