Omc 25h.p.

[DonChichoJr.]

I JUST BOUGHT AN OMC 25 H.P., 1998, SHORT SHAFT, IN A+ CONDITION.
HAS ALREADY DONE AN EXHAUST RELIEVE HOLES IN THE L/U .

I WOULD LIKE TO IMPROVE THE TOP END OF THAT PONNY .

THE CARB # IS : 439377 . WITH #58D INTERMEDIATE JET AND #69D H.S. JET.

THE PACK IS A RAPAIR NON-LIMITER . AND USING A SST 10 1/2x11 PROP .
I'M USING A 95 OCTANE GAS WITH PENNZOIL 100% SYNTHETIC OIL (40-1)

CAN I BE ABLE TO MILL THE HEAD ???
HOW ABOUT TO INSTALL A BIGGER CARB ????

P.S.: I BOUGHT A SET OF BOYESEN REEDS. BUT, LOOKING THAT SMALL PIECES, I'M SURE IS A "PIN IN A..."!, TO INSTALL IT .
I JUST KEEP THE STEEL ONES .


THANKS,
DON

[Fast Fred]

if you got fiber reeds put them in. see if a 30hp carb is biger , or the next bigest size that will fit, compression, see ware it is at now, at 125 psi or lower,
you don't need high octain, prob' make more power on reg

[DonChichoJr.]

The 25 H.p. & 30 H.p., Carb Are The Same. It's Only Change The Medium Jet And The Hi-speed Jet , That I Already Installed It ( 30 H.p.) . I Dodn't Know If Using Hi-octane Gas, Can I Go Up With The Timing ( 32 Degrees ???).

The Boyesen Reeds Are Coming In A Small Pieces, It's Not Coming In A Solid Piece. You Have To Align The Pieces !, Waohhh., A Lot Of Trouble To Align That Small Pieces !!!!!!!!!!

Thanks,
Don

[DonChichoJr.]

.................or using a SPLIT FIRE 264D PLUGS ??!!

REGARDS,
DON

[DonChichoJr.]

Thanks, By The Way......, I Will Try To Install Those Fancy Small Plastic Reeds (boyesen) .

Don

[17W]

There is a difference in port timing from the 25 to the 30. They also do not run the same intake manifold. You can get the larger carb but performance increase will not meet your expectations.

Split Fire Plugs......every engine I seen running Split Fire Plugs was torn apart for rebuild.

[adila]

,,I WOULD LIKE TO IMPROVE THE TOP END OF THAT PONNY" ...with SST 10 1/2x11 PROP ???!!! Too small pitch! What gear ratio is your 25 hp? 2.15/1?
You can try one SST prop 10x17 (omc#390731)...or an aluminium 391064(10x17)...

[Jeff Akers]

17[/B] (omc#390731)...or an aluminium 391064(10x17)...

That omc 390731 is NLA .... I'm looking for one myself

Just a note on the carb thing...... That engine can use any OMC (SV) carb,
SV meening Side Vent. So that gives you a range of carb options from 20hp through 75hp models

[QUINAULTRACING]

Looking for what would be best for use as marathon or sport C engine. 1980-2005, 20hp Thur 35hp, two cylinder cross-flow or 1996-2001, 25,30, & 35hp, three cylinder loop-charged ? Correct me if I am wrong but I think both are two stroke. THANKS..steve

[17W]

Looking for what would be best for use as marathon or sport C engine. 1980-2005, 20hp Thur 35hp, two cylinder cross-flow or 1996-2001, 25,30, & 35hp, three cylinder loop-charged ? Correct me if I am wrong but I think both are two stroke. THANKS..steve

Use the 3cyl 35hp.....if you can obtain a powerpack w/out a rev limiter.