trying to increase power from yamaha 25hp

[pete egde]

Hi guys, I am trying to find a way of increasing the power to my 25hp yamaha engine? Is this possible or do i have to chop in for a 30-35 hp. Any ideas would be grateful. Thanks

 

[triumphrick]

Re: trying to increase power from yamaha 25hp

You may not get many replies, so here goes. That finely crafted, perfectly designed Yammy makes 25hp for areason. It is built that way. We got no cold air induction, dual pipes or nitrous we can throw on these things!
Most attempts at increasing carb jet sizes, playing with timing, etc tend to screw up a perfectly fine running motor.
Yeah, if you need more umph, put on a bigger motor!
By the way, welcome to iboats..it's a great forum for fixing, buying and doing most boat stuff. Good luck!

 

[pete egde]

Re: trying to increase power from yamaha 25hp

Top man!
thanks for that. i sure made an error buying a 25 then. The thing is i have spent a few long hard years redesigning a 9ft 6 jet boat, origionally used on still calm waters with a 500cc rotax engine..... extremely fast, but i now use it in choppy waters and was forever blowing it up, changed then to a jetski engine.. kept blowing that too.
so chopped it up to take an out board and complete redesign.
but now she is very stable but just too slow coz i thort the weight of any more than a 25 wud be dangerous!!
How do i find a limit to what size engine it could take ? or do u reckon i shud just grow even bigger balls and go for a 40

 

[triumphrick]

Re: trying to increase power from yamaha 25hp

Dude, there is a guy on another forum putting two 235's on a 19' boat, so who am I to say the 40 will be too much! The consensus on this forum seems to be toward safety, using the manufacturers rated horsepower as your maximum. There are issues of safety for yourself and others if using a larger motor. Also liability and insurance issues.
If you can find what the hull was rated for then that's a good place to start looking for the "proper" size. If none of the above matters and you want to throw a little caution to the wind, try two 40's!

 

[pete egde]

Re: trying to increase power from yamaha 25hp

:d Cheers Dude... Ps Its A Pete Hull.. My Own Style!!
Have To Spend On Big Hp Then Lmao
Safety My Arse

 

[triumphrick]

Re: trying to increase power from yamaha 25hp

Great, man. we all can use a little more style...so how bout some pics of the beast??