Does it look like this one.You can just barly make out the rails already on the side like a glow engine.If it does,its the 28cc,or 27.2 nactual.Threads on crank are 8x1.25mm.I have a 25 im doing also.Aaaaaaaand 2x 23ccs im also doing.Muffler was done by lambertsrc,check with him,i dont know if he has any left.Sensor ring[for magnet],i used a hole saw and cut the center out of flywheel then trued up on my lathe.A flat back plate would be easier unless its like mine pictured.If your intake alighns the throttle for a straight shot dont worry about it.If not,somtimes you can use the carb mounting bolts but use longer ones and just use 2 bolts to hold on the carb and intake at once.