What are the differences in Yamaha 225 and 250 4 stroke engines

[John Toutkoushian]

I think the two engines are basicly the same except for a few things to increase the HP, can you change the 225 into a 250 ?
John

 

[JB]

Re: What are the differences in Yamaha 225 and 250 4 stroke engines

Some possibilities:

Cam timing
ECM injector and ignition maps
Compression ratio
Exhaust geometry
Valve sizes

Or combinations of the above.

I think it is possible to turn one into the other, but doubt that it would be cost effective. Cheaper to trade.

 

[WillyBWright]

Re: What are the differences in Yamaha 225 and 250 4 stroke engines

Adding 25Hp to a 50Hp would be significant. Adding 25Hp to a 225Hp would barely be noticable. Maybe another 2 or 3 mph...maybe. You'd be better off playing with props.

 

[rodbolt]

Re: What are the differences in Yamaha 225 and 250 4 stroke engines

while the engines share similar block and head designs thats where all similarities cease.
after the fact they share the same basic mechanical desighns they are totally different motors.