Omc 25h.p.

[adila]

[QUOTE=Jeff Akers]That omc 390731 is NLA .... I'm looking for one myself
I have one sst 390731 and an 391o64. I'm looking 4 an cleaver 11x18...19 or 20" with 14 splines( Johnson 25-35hp).

[Dago Fast]

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

I have one for sale. Also have 40mc Nissan 2 cyl short shaft for sale.

Dago Fast

[DonChichoJr.]

DOES SOMEBODY HAVE TESTED A "HOTSHOT" PROP ? (MADE BY TURBO PROPS ), FOR THOSE SMALL PONNIES .

ARE THOSE PROPS BETTER THAN THE OMC SST's???

REGARDS,
DON

[adila]

ARE THOSE PROPS BETTER THAN THE OMC SST's???
I didn't test hotshot props ...I was jumping directly at cleavers and more pitch.

[JohnsonM50]

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

does this carb have a hi speed adjust needle? Im more used to 70s engines and have installed hi speed needles thru the drain hole using a brass plumbing fitting with the center threaded to the omc lo speed needle size, a drilled over jet and an 1/8 in cut of fuel hose in place of the compression collar to seal it. Ive run these up to 6700 Rs. Also when you take the reeds apart hold the manifold over the reed plate [w/o the reeds] look thru backwards and see how well or NOT they match up. the machined surface of the manifold covers up to 3/16in. of potential flow at the outer edge of the reeds. Between all that and getting more exhaust out, [relief holes might help] but im still working on that .

[DonChichoJr.]

THE CARB DOESN'T HAVE A HI-SPEED ADJ. THE CARB USE A FIXED HI-SPEED JET . THE STOCK ONE IS A 67d AND I INSTALLED A 69d .

THANKS,
DON

[JohnsonM50]

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

Ive heard that a rev limited power pack would have an R in its #s Ive also heard the 2 cyls arent limited, dont know for sure. Im running an OMC 31.8 2 cyl crossflow at up to 6900 Rs on a C hydro, the powerheads factory, the carbs worked, the time is locked. a 3/4in relief hole is drilled in the sorta stock lower and Im playin w/ props to get it to go

[JohnsonM50]

Ive heard that a rev limited power pack would have an R in its #s Ive also heard the 2 cyls arent limited, dont know for sure. Im running an OMC 31.8 2 cyl crossflow at up to 6900 Rs on a C hydro, the powerheads factory, the carbs worked, the time is locked. a 3/4in relief hole is drilled in the sorta stock lower and Im playin w/ props to get it to go

Oh, forgot to mention, I lightened the crap out of the flywheel, if you look at it ,its made to start 3 ways I got rid of em all and put a MK25 spool on and took a ton of junk off the motor too.

[Mark75H]

Oh, forgot to mention, I lightened the crap out of the flywheel, if you look at it ,its made to start 3 ways I got rid of em all and put a MK25 spool on and took a ton of junk off the motor too.

Be careful, some flywheel lightening is dangerous; there are sections on some flywheels that look like dead weight, but are actually part of the flywheel's strength

[JohnsonM50]

Be careful, some flywheel lightening is dangerous; there are sections on some flywheels that look like dead weight, but are actually part of the flywheel's strength

Thanks Sam, Ive had that in mind and looked it over before and after running, I also bench spun it at around 9 - 9,5 g before putting it on a motor. I probably should test with more rpm but thats all Ive got for now.
I will look it over under a magnifying glass. Mike: eek: