Converting 1966 Johnson 20 HP to 25 HP

[arcadiainc]

Is this motor a likely candidate to be converted to a 25 HP. I need the power. 20 HP will just get my boat on plane. I feel that a 20 percent increase in power would get her going. If it can be converted what do I need? Carb and clean up the intake manifold or?

 

[Feathercraf1]

Re: Converting 1966 Johnson 20 HP to 25 HP

I've never noticed any difference between 20 and 25hp parts (let me know)

You could benifit from some DEEP RESEARCH on a prop change.
Yes, I know they are hard to find.

How old are your points? Have you a wire feeler gage? This IS CRITICAL.

A clean wire gage! Polish after with a buisness card.

Have you tried synthetic oil instead of the fuel mix that you are using now?
I'll bet that I could get you a difference using pure gasoline (higher BTUs) and synthetic oil mix. I don't mean Synthetic Blend - you need PURE.
Ethanol sux.

I'm 6ft 200lbs and I have skiied behind an 18 hp Buccaneer (OMC) with two other hogheads in the boat.