Hi,

I have a 120 NC I bought 2nd hand with what the previous owner stated was around 30 or so runs on it. After running it for around 10 flights myself with great success I noticed that the top end had begun to sag after about 10 seconds from around 8800 RPM (16x8 prop) to 6500 or so. I assumed that the engine was probably running to lean and it was the end of the day so I just packed up without doing to much to it on the ground. When I got it home, I did a tappet adjustment for the first time using standard .04 and .1 feeler gauges. One tappet was definitely below .04 so I loosend it up a bit to get back to spec. After reassembling the engine, I noticed that turning the prop through was not as smooth as it used to be. So when I started it up today with my Sullivan Starter (I know prob a bad idea) the engine seized. Prior to that I had turned the prop over around 4 times to pressurize the tank but never saw any fuel moving into the carb...sure enough, after releasing the vent plug, nothing came out.

I put it on my work table tonight and removed the carb housing to expose the backplate and the engine seize was gone! My only guess would be vapor lock but I doubt it since I was able to rotate the prop 359 degrees. I want to get in there further but I can't figure out how to remove the second backplate. At this point I'm guessing a bearing must have popped out or something.

Any ideas?

Thanks

John