The pilot was performing a post inspection test flight of the gyroplane. Prior to the flight, the pilot noticed the control stick pressures were greater than he had experienced with other gyroplanes he had previously flown. The gyroplane’s owner and a mechanic explained the gyroplane’s trim system to the pilot who then adjusted the trim to a setting he assumed would be sufficient to maintain control when the gyroplane was airborne. During takeoff, the gyroplane pitched up and when the pilot attempted to arrest the motion, the backstick forces on the control stick were greater than expected. The pilot lost control of the gyroplane as it continued to pitch upwards, so he reduced the engine power. The gyroplane had pitched to about 60° nose high, rolled left, and impacted the ground resulting in substantial damage. The pilot had flown several models of gyroplanes but had no flight experience in the accident gyroplane. After the accident, the pilot further learned that the gyroplane’s trim had previously been modified with a heavier trim spring which made this gyroplane respond differently than other gyroplanes.