I have 2 .65LA engines, one in WM Super Chipmunk, and the other in a 4*60, both are great running engines. Easy starting and dependable. Have been using Cool Power 10% and have had no trouble yet. At an advertised 1.7 hp it only makes as much as a .46 AX, but swings a larger prop. Mine does fine in the Chipmunk, not a powerhouse but gets the job done. I see now that World Models has the Super Chipmunk rated for a .91. Might have to save up my pennies.