raknsak

I have an os fs 70 s surpass . recently put it on a new mojo 40 profile . now it vibrates bad at half throttle or higher. did not do this on last profile .prop is balanced exactly. crank not bent at all. it sounds like the covering is shaking . but it's all tight. engine has maybe 10 hours on it. any suggestions?

nitro wing

My Feedback: (1)

I, and most others would certainly suggest re balancing the prop, and if you got a spinner, maybe not use it or balance it if possible. make sure the blade does NOT touch the spinner cone at all. Try another prop, maybe it has a crushed hub. or is otherwise defective

Recheck all the engine mount bolts, also make sure you torque the engine onto the mount evenly,in sequence, to avoid distortion of the case.

zacharyR

My Feedback: (5)

check the vale lash also

Jezmo

There may be a harmonic issue at work here. The power pulse of the engine may be in tune with the elasticity of the fuse leading to some kind of harmonic twisting effect being felt as vibration. When it starts the vibration are the cylinder and head visibly shaking back and forth significantly? If not then the above suggestions should point to the answer.