I am new to RC airplanes. I was given an Eagle 2 ARF as a present a few years back. My dad gave me a K&B .40 engine that has never been used but it is over 10 years old. Is there anything wrong with a never used engine that old? I mounted it to my bench the other day to test it. It started fine but I am having trouble adjusting the fuel to air ratio. It was running super rich at first (lots of fuel coming out exhaust and it was dark) but got it to a more acceptable level. What should my exhaust be like? I am still getting some excess fuel coming out...it is minor though and it is clear. (I am using a 10% fuel) Any advice? Thanks in advance.