That's an old G-23 carb that I'll use until I get another 11mm. Walbro. The sensor ring is a light press fit on the nub on the rear of the motor (that is identical to the nub on the front of the motor) It fits tight enough that I can use a drop of locktite or a tiny dab of J-B weld to make the final permanent installation. You've got to fit all of this together "dry" and check the timing to find the exact location for the pulse switch. Stock crank, LH external threads on both ends. Motor rotation will keep the timing wheel tight on the rear end (no jam nut needed) with just a drop of locktite.