Re: Yamaha hp increase
This question comes up time and time again with various makes of engines. 2 cycle engines are different than auto engines and a carb change to a larger carb will most likely give you-----25 horsepower-----
Even if you did gain say 10% more horsepower, that puts you up to 27 1/2 hp and maybe 1 mph more--hardly worth the effort.
While the 25 may share the same block as say a 30 or 35, the bore and stroke are usually different, the lower units may have different gear ratios, they may be propped differently, and the bypass and exhaust ports will be cut differently.
You really need to invest significant time, effort and money to gain any significant increase in hp. ---And then you need to worry about reliability issues. Much easier to just buy a larger engine unless you are a die-hard, hot-rodding for racing purposes
