RE: Super Tigre 75 with a YS Carb
The YS is a pressure carb. It is designed to work with a pressurized fuel system. Without a pump, it will cut out suddenly at higher throttle settings.
You could try a Perry VP-30 pump and a one way check valve on your muffler pressure tap. That should do the trick.
The pump will feed constant pressure to the carb, while muffler pressure will pressurize the fuel tank and feed the pump.
Or, take the easy way out and buy the correct carb for that engine.
Doug