os 91 fx knock/ping
first of all THANKS!! WHAT A COOL SERVICE!!
OK I have one of the 91 fx powerhouses and it give my four star 60 unlimited vertical, but IT KNOCKS at lower throttle positions 1/4 to 1/3 . i have stopped flying this plane because i,m afraid to damage the motor. reliable experienced assistance was available for break in and setting the needle valve and low settings . we tried richening up the low setting but this caused it to load up and die. DEAD stick low over the pond was "fun"! i was careful to seal the needle valve assembly and fuel lines etc. and it runs fine except for the knock in my cruise rpm area, any sugestions. DSIP