3w 50i runs just great but after a flight it looses most of its compression. After the engine sits for a while and cools down the compression is as normal. The repair guy says the motor is getting too hot. I think that this might be a piston / ring problem. Oh, the ring was just replaced because of this problem and still happens.

FYI......( The plane is a yak with an open front and pleanty of vents for air to pass through the cowl )

Any thoughts?

You want ALL the air coming into the cowl to have to go over the engine. What goes by the engine 1/2" away is a minus for cooling not a plus.

Rich,

So you think the front of the cowl should be blocked for me like your pict shows then,rather than totally open?