I got an Aurora 650 off ebay. Put a CL venturi and Super Tigre NVA in it. Engine was said to have been flown a few times RC. Ran it on the bench. Second run the shaft bound up. Took it apart and found the thrust washer galling on the front of the case. The brass collet is a little too small. The cut in the collet was obviously made by hand with a hacksaw. Anyway, it worked to put a glowplug washer between the collet and the shoulder on the crankshaft. Ran a full 4 oz of fuel through in one run with no sag or loss of power. The engine is not being particularly powerful. 7800 on a Taipan 11 x 5. about the same as my Fox stunt 35 on the same prop. 6500 on a Graupner 12 x 6. the venturi hole is fairly small. I may try opening it a little as those figures are low for a diesel 40.