This was the FIRST 2 seater SB around I was told. A 503 would not have lifted the two of us, I would have thought.. We were not lightweights. I could be wrong. It WAS a Pull start. You could NOT reduce the Power much when you levelled off. I did not have much Notice of the flight. When it was offered I thought well I'll Probably have to do it sometime and he was an F/O I'd done a lot of flying with. and trusted. I flew it all the time. I wasn't a passenger. Must have taken six Minutes. The Plane was very New. That helps. Nev