CHANGING......2004 , YAMAHA 4 stroke 4hp --->5 or 6hp ----> HOW?

Firstly I've hearld that swapping out the carb of the 4hp for a 5 or 6 is the fix

then I've also seen that the exhaust ports inlet/outlet are different.

is there no one out there who is a qualified YAMAHA outboard mechanic who currently works
in the japanese factory to help out?????

cheers

First it is illegal here in USA

Just look at part numbers, most it's just the jets

justintime said:

First it is illegal here in USA

Just look at part numbers, most it's just the jets

Click to expand...

Hey , the email is to someone with engineering experience NOT to someone pretending to know about legalities about 4stroke upgrades from 4hp to 6hp.


Secondly, please, please could I have a person replying with some sort of an engineering background who has done it
and is willing to provide their take on the changeover. Any reply with some reference pictures showing the parts would be a added bonus,

otherwise dont bother replying about legalities and spoiling it for everyone else.

Well it's just the carb jets and exhaust tuner, that's it

ranuplh,

It doesn't take an engineer or mechanic from the factory in Japan, just someone mechanically competent to look at parts diagrams to identify the parts that differ and swap them out. And maybe reading a service manual to make the proper adjustments based on the new horsepower. That's all there is to it. Modifying an engine to change the horsepower will not be something covered in a service manual so there won't be any pictures. There are full parts diagrams available online.

Nobody is "pretending" to know about the legalities, it's common knowledge.

ranuplh, please use a civil tone in your replies. It's in everyone's best interest to keep this forum a place for community and cooperation. Thank you.

-James @ MarineEngine
Forum Admin