I don't have any experience of the 57 but I presume it shares most of the same bits as the 56 which my son has been using for the last couple of years. If so our experience may be of interest. This engine proved to be easy starting with good throttling (which was pretty importand as it was being used for 3D in the Stiletto featured in RCM&E a couple of years ago). The experience wasn't all problem free though. The first enging developed a knock during running in which turned out to be a worn big end. Just Engines repaired it promptly with the comment about using castor in the fuel, which we were anyway. The repaired engine performed well until a few months later the piston split around the gudgeon pin hole and exited through the crank case. JE replaced the engine free of charge but again blamed under oiling. In JE's defence I have to say that we were trying to squeeze every ounce of power out of it for the 3D stuff, but this didn't mean outrageous revs or super lean running so the explosive demise was still a bit of a surprise. Anyway, this replacement engine continued to perform well until a familiar knocking noise indicated another worn big end. On this occasion I simply ordered a spare from JE and fitted it myself. The phosphor bronze bush on the original had worn egg shaped. In summary I would say that the 56 was a good performer albeit a little fragile in the con rod area. So long as you are using a good fuel, don't run it lean and don't try to wring it's neck you shouldn't have too many problems and even if the con rod does wear the replacements are cheap. If JE have uprated the con rod for the 57 I would expect it to be an engine well worth having
