ORIGINAL: ErikElvis
by the way i went from a tad over 10k with a 14X6 to about 10,400rpm with the 13X8. I figure the engine is plenty safe at 10,500 on the ground. It still is a lil rich as it isnt that old. Think 10,500 is a good ground rpm for say a 13X10 prop? The engine should safely pull over 11 in the air.
Erik, I reckon you'll get between 9200 and 9400 static with the 13 x 10 and will get at least as much speed as you got with the 13 x 8. The OS .91 Surpass is virtually indestructable so it won't mind running at those rpm figures you quoted for the 13 x 8 at all. Let us know what you find.
Edited to add: If your minnow is set up nicely, you should get over 100 mph with the right prop.