Leaking or sticking valve.
Note:
In some cases, fuel tanks made out of com-
posite materials have been proven to be in-
compatible with the fuel, thus causing the
tank material to dissolve. In such cases, the
complete fuel system must be cleaned or
even be re placed.
Strong accumulation of deposit in the
Demount cylinder heads, remove deposits.
Balance propeller. Check propeller blade
track.
Engine suspension defective.
Replace engine suspension.
Excessive gas leakage at the piston.