I recently completed my first build, and I thought I put everything together correctly. After filling the tank with 1:16 oil gas mix, I attempted to start it like everyone does by pedaling with the clutch pedal squeezed, and then slowly letting the clutch engage as I hold down the throttle. When I let go of the clutch, the engine does turn over, but it does not provide any thrust at all, and quickly dies down to a stop. It will not idle, and will only run if I assist it by pedaling. Is there a part broken, or do I have to adjust something?