more hp from an out board ?

[Nico.d.R]

I have a 25hp johno and i was wondering if it can fit a bigger carby or if there is anything that can be done to get more hp out of it . I have heard that you can put a 15hp carby on a 9.9 to make it a 15 with out any other mods .

cheers nico

[Poodroo]

I reckon if the outboard is running well leave it alone. If you start tinkering with it by trying to increase horsepower and changing carburetors then you may end up with problems. Why do you want to change the horsepower Nico? Is it under powered for the hull? What sort of boat is it on? If it is maximum rated to take a larger motor then I would probably look at a 30 hp or something.

Poodroo

[FNQCairns]

Nico your motor is also the 30hp (i think?), if it is the 20hp - forgetaboutit .
If the 30hp print out the complete parts list of each from wherever you can find it on the net and compare, the different part numbers between each will tell you exactly what is required to make a 30hp out of yours.

Although you may find an extra 5hp you will more than likely loose low to mid range grunt and the extra 5hp will only be noticeable up high in the rev range - everywhere else will be doughy-er, although if the change up does not include larger bore carbs you may find an improvement near everywhere.

cheers fnq

[Nico.d.R]

just an idea poods , get to the fishing spot quicker . its on a 4m tinny max speed is about 42 k's which is ok (i think) . the boat is rated to a maximium of 30hp or 75 kg , so i want to eventully get a 30hp but i was thinking about the bigger carby untill i can afford a brand new 30 , but by the sounds of it , its not really worth it .
fnq it is a 25 .

thanks nico

[FNQCairns]

just an idea poods , get to the fishing spot quicker . its on a 4m tinny max speed is about 42 k's which is ok (i think) . the boat is rated to a maximium of 30hp or 75 kg , so i want to eventully get a 30hp but i was thinking about the bigger carby untill i can afford a brand new 30 , but by the sounds of it , its not really worth it .
fnq it is a 25 .

thanks nico

Hi again nico, yeah I know and I just remembered the one I had was the 30hp (was only 3 years ago, how embarrassment:-[ :D), it shares the same block and I suspect 98.5% of all of the parts your 25hp does, try printing out the parts list for both the 25hp and the 30hp and do the comparison you will know for sure then what it will take to go to 30hp.

cheers fnq

[Spaniard_King]

The 25 Johno can be upgraded to the 30 by simply changing the carby... from memory around $250 for the carby. The 30 has a noticibly larger throat in the carby and jetting to suite (including the mid range stuff:0 )

[Noelm]

this comes up all the time, but in most cases, changing the carby results in more fuel use, bad performance and less power(usually) just because a range of Motors share a common block (so it seems) they can be entirely different. a bigger carby without the correct exhaust, port timing (that cannot be changed) and some other odds and ends, just gives you a rich running motor, you can achieve that by pulling the choke half way out!

[Spaniard_King]

Noel, I have been through this.. and done it.. carby only needed :)

[Nico.d.R]

ill look into the parts list thanks for your opinions and help .

nico