1. Would someone please explain how the reed (valve?) works. Fuel flow controlled by needle valve, fuel travels down center tube and strikes reed, through screen to combustion chamber... correct? Does the reed actually atomize the fuel?
Like Phillip said -- it's a one way valve. The two-stroke engines that we use get fuel and air from the venturi and into the cylinder by using the crankcase as a pump to draw in air from the outside as the piston moves up, and to push it into the cylinder close to the bottom of the stroke. The reed valve lets the air flow when the crankcase pressure is lower than atmospheric, and closes it off when the crankcase pressure rises.
The reed valve probably does little to atomize the fuel -- it's purpose is to control induction into the crankcase.
2. Is pharmaceutical grade castor oil OK to use when mixing fuel or must it be something from the hobby store? I would like to use a bit richer oil/fuel mix during break-in.
Thanks for your time...cheers
I get fuel from our RC club's raffle; it's invariably 18% all synthetic, and all my engines are old journal-bearing engines. So I buy 8-ounce bottles of castor from the local pharmacy to add to my fuel. I haven't destroyed an engine yet -- but I haven't been back in the hobby long, so who knows what damage I'm doing?