COX Tee Dee 010 backplate gasket - DIY, if needed

Not a big invention, but may help you debug this tiny engine...

COX Tee Dee010 engines genuinely did not use a gasket between the red delrin backplate and the crankcase, thanks to the good quality of backpate mould and the flat crankcase face or flange.

I noted on at least 2 of my old-stock 010-s (black anodized carburetor, gold anodized crankcase, red delrin backplate or tank and carb body, tapered cylinder bore)  however, that no matter how much I tighten the 4 backplate screws, the backplate will leak - typically on the right side of the cranckase- indicated by small air bubbles appearing in the area between the 2 right side backplate mount bolts, when the shaft is slowly hand-cranked Counter Clockwise (like in normal operating conditions) from TDC i.e. creating compression in the crankcase with the piston moving down. I noted that this side of the crankcase face is not flat, the crankcase mounting bolt area is slightly bulged - maybe a certain material extrusion during thread tapping? -, and the backplate will not contact the crankcase face in the full circumference, resulting in leakage.

This sealing problem will  not only impair the fuel suction capability of the tiny engine, but reduce the amount of fresh air-fuel mixture inhaled into the crankcase then shot up into the cylinder, so, it may cost you starting problems on the one hand, and thousands of rpm in engine performance in an unhealthy lean run, on the other.

Not wanting to sand the crankcase face flat, nor having any stock gasket around (never manufactured by COX anytime, anyway), I wound some plumbers' white thin PTFE seal band around the central plug element of the backplate before mounting it back on the engine, then shoved it down to the sealing area to create an artificial PTFE O-ring to sit on the crankcase face, and - low and behold   -  the sealing problem disappeared.

Now, with the glow head removed and the piston hand-cranked CCW from the TDC down, it will slightly spring back when the shaft is released -  release the shaft before the piston crown clears the transfer ports - in an indication of a healthy compression created in the crankcase by the sinking piston.

Those CEF friends running 010-s may check their own backplates for proper sealing, it is worth it.