What are u trying to improve with your motor?
There's alots of propeller selections for the yami 25.
I had a cheenoe classic with 25hp 2-stroke yamaha. Tops out 31.5 mph with stock propelller at 6250 RPM.
So I switched to 10 x 13" pitch stainless steel propeller to lower my RPM and gain bit more speed.
When I got a electric jackplate then I switched to 10 x 11" pitch 4 blade stainless steel propeller with heavy cupped to run very shallow. Tops out 29 mph with 4 blade.
For best overall performance is 10 x 12" pitch stainless steel 3 blade propeller.
I don't see nothing is wrong with stock propeller like 11 7/8" pitch only comes with short shaft.
If u have a long shaft then you have a 9" stock propeller come with it.
Let us know.