2002 Nissan NSF25A - Conversion from 25hp to 30hp

[scjakester]

Hello folks... may I get your advice on this? Some of the sites say the engine I have (a NSF25A 2002 25hp Nissan carburetor, tiller) is actually a 30hp engine governed to 25hp through something called a "restrictor plate". Is this true? Is it really the exact same engine? I have a kinda heavy j16 Carolina Skiff and it would be nice to have just a little more umph, but only if it is 100% safe for the long term health of the engine. I'm a really conservative kind of guy, I would much rather have a good smooth reliable 25hp engine than a 30hp that I'd worry about stressing or overheating.

Assuming it isn't harmful to the engine in any way; is swapping it over to a 30hp a simple DIY job or something more involved requiring a skilled mechanic's help? Does it require any special tools or would I need to do anything complex like resynchronize the carburetors or something?

-Jake A.
Lake Murray
South Carolina

 

[pvanv]

Re: 2002 Nissan NSF25A - Conversion from 25hp to 30hp

It wouldn't be harmful, but probably wouldn't be cost effective. No, there isn't any restrictor plate (that technique was used on some older 2-strokes). The blocks for the NSF25A and 30A are the same, but the carbs are different. The carb throats on the NSF30 are larger than the 25. You would need to swap out all 3 carburetors:
3R0032001M CARBURETOR, UPPER ASSY F30A $212.37
3R0032041M CARBURETOR, CENTER ASSY F30A $212.37
3R0032101M CARBURETOR, LOWER ASSY F30A $212.37

And yes, of course, you would need to synchronize the carbs after installation.

 

[scjakester]

Re: 2002 Nissan NSF25A - Conversion from 25hp to 30hp

Thanks (again) Paul... I appreciate the input, a factory 25 hp it shall stay. -Jake

 

[Sea Rider]

Re: 2002 Nissan NSF25A - Conversion from 25hp to 30hp

Thanks (again) Paul... I appreciate the input, a factory 25 hp it shall stay. -Jake

A pitty was not a 2 strokes same HP version, just a $ 5 cost carb gasket swap

Happy Boating