upping the grunt

[doorstop]

Hi all, I hope this isn't a stupid Q.... A young mate just bought a tinny with a Tohatsu 25 on the back (all brand new), the dealer is going to raise the horsepower rating to 30, apparently just by changing some gaskets etc as soon as the motor is run in.
Now I have a Yamaha 40 on my boat but a few more neddies would be nice...... is it possible to change/upgrade the Yam (12 months old) without anything outrageous being done?

[krazyfisher]

The reason that it can be done on the tohatsu is that the 25 and 30 are the same motor with the 25 detuned through the smaller exhaust this can be done on some yammies but I think it is the 20 will go 25 but it is worth checking.
have fun

[doorstop]

Thanks Krazy, unfortunately my local Yam dealer is not very interested once he has sold the motor and all the answer I can get from him is "I dunno... maybe.... er... I really dunno" he is far more interested in motorcycles than boats even though boats are his main business.
I was under the impression that the 40 was a detuned 50 but I don't know how it is detuned..... and mechanicals are not really my forte. Any help from a knowledgable mechanical type fisho would be much appreciated.