We at Mesa AZ run the Graupner 14x7 prop and the engine turns about 9500 on the ground. They run, cool, and perfect for many hours. See RCENGMAN on this site for more data. He is the best YS Engine repairman I have known. He can "soup them up" also. Changes the timing, lap surfaces etc. for a fee of course.

You can buy the 14X7 p/n 1316/36/18 Graupner props from Central HObbies or new creationsrc in Texas at a good price. This is the prop Graupner recommends for YS91 engines. Try them out! Just my .02cents worth.


dickj