The GY520 is simply amazing.

I have been asked by YS to help develop the YS56.  This took over a year to do and after several revisions we are happy with the end result.  Anyone who buys this engine should be very pleased with the smooth power of delivery.

After testing the YS 50 ST engine, I have found it to have plenty of power while maintaining excellent fuel economy for an engine of this size. The engine also runs very smooth. Overall, an excellent motor for this displacement class.