Mercury 25 Hp mods

[Mark75H]

X's 2 on the idle releifs the comp will come way up simple mod

Cranking compression will increase, but I am not convinced there will be any effective power increase while the motor is running ... but you can try it anyway

[thezohan386]

Ya lots you can do to those 25's we race em.. open your intake ports(Not your out ports) they have a compression release on both cylinders, you plug up with glue. take your exhaust cover off and you'll see them, the hole is about big as a small screw in to the cylinder.. your compression should go from 150lbs to about 170lbs per cylinder.. you can still burn reg gas too.. lots lots more you can do but i give all my secrets out..

What are you calling the compression release? Can you post a picture?

[ChrisCarsonMarine]

we sell reeds for your motor that will help at all rpms. 24$ in stock ready to ship
chris,

[Mark75H]

What are you calling the compression release? Can you post a picture?

Its a tiny hole drilled in the cylinder above the exhaust port down into the exhaust passage.