I've recently purchased a Irvine Tutor 40 with a Thunder Tiger GP 42 engine. Planes built but i have the following question.

1 - As standard the engine carburetter had a tube inlet and i was supplied a needle valve as an extra. However if i unscrew the exisiting part the needle valve doesnt fit or screw in to the carb.
I tried to start the engine but nothing happend.

I've noticed if i turn the engine by hand it rotates but does get fairly stiff at a point. Once i've applied more presure it turns. How stiff should the piston be when moving the prop by hand.

2 - when i increse the throlle the rudder also turns (even though they are seperate servo's

3 - Is the need valve even needed?

many many thanks

gareth