I/O Performance Advise

[martin]

Perhaps to much pitch.. or maybe the prop is to small in diameter
Sooru wish I could be mor help

[Blackfin26]

Guessing a 22 or 24 pitch prop would be what you need... I'd go with a 22.

[bitsamonkey]

I'd have that prop measured to be sure it's a 26" prop. Speed seems about right for that combo.