25hp to 30hp Johnson

I have a 1999 25hp Johnson J2

I have a 1999 25hp Johnson J23TEEEN and have been told that with a carburetor change it will develop 30 hp. Seems too easy. What is the correct answer? Thanks.

" The difference in nominal po

" The difference in nominal power is 20%.
Probably the 25 is a throttled 30hp, the bigger carb of the 30 might be sufficient then.
The 30hp has an 1.5 inch carb.
Measure out the diameter of the throttle.
If it's less than 1.4 '' the carb of the 30 will probably do it.
Look at the valve in the crankcase in any case.
There must be ca. 10 diaphragms in a circle.
If You have less, you must have the more breathing valve of the 30 too.

I have a 30hp.
I wasn't satisfied with the performance at all.
So I opened and rounded the carb's mouth, which is original sharp-edged.
Further I widened the narrow air passage in the carb and bored the fuel jet to suit the air/fuel ratio (plugs must be dark brown driving full speed).
Last not least I increased compression ratio by grinding off the power head (0.028 inch).
The result was much better acceleration and top speed.
I prefer high octane gas (95-98 ROZ), not to slow down the ignition timing (30 °).

You see a lot speaks for the hypothesis, the 25 is a throttled 30. "