I have a new K&B Sportster .65 engine. It is a light and reasonably powerful engine (APC 13x7 @ 10,200RPM). I am having problems with the mixture going lean gradually between 1/2 and 2/3 of the tank? I use a Dubro 8oz tank with all new hoses and pipes and as high in it's compartment as possible. Tank is surrounded by foam. The remote needle is rigidly mounted at the same height as the spray bar. There are NO bubbles in the fuel line while running (full or not). I have enlarged the hole in the exhaust pressure tap. I have enlarged the id of the pressure line. The spray bar is 3/8 of an inch below the top of the tank (I had to lower the engine).

If I start the flight sloppy rich then I get rather weak performance for about four minutes. Perfect running for four minutes and after that it gets leaner and leaner till it quits. This is a gradual change NOT sudden! My Goldberg Tiger 60 is easy enough to dead-stick but I love the power when set 300 RPM below peak.

Do I need a Cline regulator? Do I need a Perry pump?

Anybody try the fuel system in the attached drawing? Does it work?

Francis