Osprey 170 possible repower....Optimax 125?

[powersportcomposites]

I have a 170 Osprey with a old 70's Javelin 100hp.
I have figured the gas mileage at approx 2.3 mpg. (I know outboard fuel consumption is generally measured in gph but I find it easier to chart my distance covered and compare to fuel used.) I'm considering selling the javelin for the little it might be worth ($1,000????) and repower with something more efficient. I want to stay with 2 stroke. Maybe an optimax 125, or even a 90 if its not too underpowered.
My question for you guys....if I repowered to a more modern 2 stroke motor, what difference if consumption could I expect, and what would I be paying for a optimax that's 5 or so years old?

[pete]

A 90 or at most a 115 is ideal for that boat,heck even a 70 would do.

[wingtime]

A 90hp will be more than enough power.  That's what I have on mine. Remember your old motor  hp was rated at the crank and was probably only putting 70 or so hp at the prop.  Newer motors are rated at the prop