more hp out of my 20 merc

[atk81]

i have a 20 hp merc year 2000.
i've already swapped my 20 carb for a 25, tampered with the exhaust and the reed block. ny friend has a 25 merc and he can still get by my. is there any other differences in the 20 and 25 powerheads?

[will350]

I really don't know for sure but OMCs MO on differences between "same" displacement motors was mainly carburation,timing and (sometimes) internal exhaust tuning. You might check the part number on the CDI and see if it's the same. If it's not,the difference may lie in the advance curve and amount of advance (possibly the rev limiter too). You might want to take a peek at your friends prop too(assuming your boats are the same weight and style)
This is just a guess.
Will

i have a 20 hp merc year 2000.
i've already swapped my 20 carb for a 25, tampered with the exhaust and the reed block. ny friend has a 25 merc and he can still get by my. is there any other differences in the 20 and 25 powerheads?

[atk81]

juat looking for a few more threads on this topic
thanx

[DonChichoJr.]

Merc 20 & 25 H.p. ( '83 To Present), Are The Same Block.
In My Case. I Own A Mercosil Block, 25 H.p., Sea-pro Model. That I Bored To .040 . I Still Waitng From Wiseco For The Pistons. They Are Telling Me,they Will Be Available Probably At The End Of Abril.
I Lapped The Reed Cage And Installed A Boyesen Reeds, Polished All The Exhaust Ports And Close The Exhaust Releive Holes At The Cyls.
I'm Using A Cabela's Ss Prop .

I Think The Diffeence Between The 20-25 H.p. Are The Carb Jets (??)

Don

[Dago Fast]

What do you mean by lapped reed cages?

D. F.

[atk81]

exhaust relieve hole... now theres something i haven't done. where would they be situated??
atk