YS fuel pressure regulator

No matter how it may be, a conventionalｌy mechanical controlled or fuel injection, any aberrant of dust into fuel line should be avoided, otherwise the throttle valve would not work fairly with smooth operation as designed. YS injection system utilizing crank case primary pressure in 2 cycle motor hates and easily loose it's performance, some crazy action at higher speed and unstable main needle valve angular position are the symptoms of dust invasion in the fuel line, most of the time, any fiber dusty material should be sticking at the valve portion. It was sure enough that a visible piece of fiber dust was found in YS regulator!
Remembering the bench test yesterday, high needle position was not stable repeating hi after low rotation. Fuel measuring was not performed adequately because of this damnable enemy, fiber dust! Motor stop situation sometimes brings the accidental airplane destruction.
An oldest YS regulator in my junk box was disassembled for careful inspection, the heart valve diaphragm inside has  different construction with metallic part at centric position. It's a matter for regｒet that the diameter of the silicon rubber is 2mm smaller than that of newer models, the size of them were redesigned. The precise guiding rod height and fitting of moving valve with the valve holding case are the most important requirement for this kind of diaphragm valve construction.
2,6-0,45 drilling tap set and 2,1 mm drill tip were prepared for a further processing to combine YS regulator body and the coupler part made by Lost-Wax method. Once tried, but failed because of casting error, lack of the casting metal material bulk. Special muffler adapters would be manufactured by my own hand making at the same time. K&B Torpedo 45 R/C and OS muffler, Forster 32 and OS old band fixing type muffler promptly for the future entry to Golden Age competition.