Can my 2002 25hp Mariner be upgraded?

[Rogue14]

Hi all, can this 2002 mariner 25hp 2 stroke be upgraded to a 30hp?

 

[jimmbo]

Go to a Dealer, make friends with the parts people, and ask them to search the part catalogs for differences regarding the the Pistons, Heads, Block, Reeds, Intake, Carbs, Exhaust manifold/cover. Exhaust Tuner,

A additional 5 HP will get you about 1 or 2 mph more

 

[Rogue14]

I know that some 25hp can go to a 30hp with a carb swap and timing change.

And from what I’ve seen it’s been more like about 7mph gain.

 

[Faztbullet]

Uh no with bolt on parts

 

[racerone]

Perhaps look into fitting a 50 HP carburetor on it.

 

[harringtondav]

I looked up your s/n. You motor is either a "Jet" or a Marathon". Here is the parts index. http://www.marineengine.com/parts/mercury_marine_parts/sn/0T472270 The "Jet" appears to have a turbo like blower on the intake or exhaust. Check out the carb jets, item #7 in each carb choice. The difference between 20 and 25 hp in each model is .032"-.034" larger jet. Merc does this on many of their lower hp outboards. Identical everything, except for a $7 jet, and $150-$200 between hp model jumps.

So you could buy another $7 jet for your carb and drill it out .030" and see what happens. Save the original in case it doesn't work out. And it may not, since you will be pushing Merc's design intent. Also your carb's bleed air and idle mix systems may not handle the extra fuel.

I checked out Mariner 30 hp models and that's a no-go, Completely different critter and intakes.

 

[Rogue14]

I looked up your s/n. You motor is either a "Jet" or a Marathon". Here is the parts index. http://www.*****************/parts/mercury_marine_parts/sn/0T472270 The "Jet" appears to have a turbo like blower on the intake or exhaust. Check out the carb jets, item #7 in each carb choice. The difference between 20 and 25 hp in each model is .032"-.034" larger jet. Merc does this on many of their lower hp outboards. Identical everything, except for a $7 jet, and $150-$200 between hp model jumps.

So you could buy another $7 jet for your carb and drill it out .030" and see what happens. Save the original in case it doesn't work out. And it may not, since you will be pushing Merc's design intent. Also your carb's bleed air and idle mix systems may not handle the extra fuel.

I checked out Mariner 30 hp models and that's a no-go, Completely different critter and intakes.

Thank you, that was exacty the kind of reply I was after!

 

[hardwater fisherman]

I looked up your s/n. You motor is either a "Jet" or a Marathon". Here is the parts index. http://www.*****************/parts/mercury_marine_parts/sn/0T472270 The "Jet" appears to have a turbo like blower on the intake or exhaust. Check out the carb jets, item #7 in each carb choice. The difference between 20 and 25 hp in each model is .032"-.034" larger jet. Merc does this on many of their lower hp outboards. Identical everything, except for a $7 jet, and $150-$200 between hp model jumps.

So you could buy another $7 jet for your carb and drill it out .030" and see what happens. Save the original in case it doesn't work out. And it may not, since you will be pushing Merc's design intent. Also your carb's bleed air and idle mix systems may not handle the extra fuel.

I checked out Mariner 30 hp models and that's a no-go, Completely different critter and intakes.

It takes more then a jet change to turn a 20hp into a 25hp...... These are not my carbs but as you can see the throat is larger on the 25hp... I converted my 20hp merc with a 25hp carb and I gained almost 800 rpms....

 

[harringtondav]

It takes more then a jet change to turn a 20hp into a 25hp

I won't disagree, but Rogue14 is at the highest hp carb for his motor. I looked at the 30 hp Mariners and saw a totally different block, intake and carb. I also cautioned him about getting too hopeful about the results of increasing his jet size. But that's the only option I could find.

 

[flyingscott]

To answer this question it is a big fat NO. Buying a Jet and or modifying the carb is a WASTE of time. A jet motor uses a jet lower unit instead of a standard prop. leave your motor alone.

 

[Rogue14]

To answer this question it is a big fat NO. Buying a Jet and or modifying the carb is a WASTE of time. A jet motor uses a jet lower unit instead of a standard prop. leave ypur motor alone.

It has a prop, so unsure of what you mean?

 

[flyingscott]

It has a prop, so unsure of what you mean?

When the parts were looked up by harringtondav he said the jet had a turbo like blower on the intake or exhaust. The difference between a marathon and a jet are one has a prop lower unit. The otherr has a jet lower unit. Powerheads are exactly the same.

 

[Rogue14]

When the parts were looked up by harringtondav he said the jet had a turbo like blower on the intake or exhaust. The difference between a marathon and a jet are one has a prop lower unit. The otherr has a jet lower unit. Powerheads are exactly the same.

Ok well mine has a prop so must be a marathon!

 

[harringtondav]

When the parts were looked up by harringtondav he said the jet had a turbo like blower on the intake or exhaust. The difference between a marathon and a jet are one has a prop lower unit. The otherr has a jet lower unit. Powerheads are exactly the same.

My bad. Rogue14 has a prop motor. I did the look-up before coffee, and forgot they actually make/made jet drive O/Bs. The carbs and carb jet size are different between the prop and jet version. .032"-.034" carb jet size increases provided 5 more hp on each model. That's why I suggested a last ditch effort to drill out his current jet, and buy a backup if this goes south. His .080 25 hp carb jet is Merc p/n 1395-6201

 

[flyingscott]

You cannot drill a jet that is a precision hole in it. That is just plain old bad advice you that can cost you a powerhead. Look into how much it costs top rebuild a blind bore Mercosil block it is not cheap. When Mercury lists that series of motors the 15/20/25 motors appear on the same parts fiche. So you have to be careful about what carb uses what jet.

 

[Rogue14]

Well I know some 25hp requires a simple gasket and timing change like in this link http://www.rib.net/forum/f36/uprating-mariner-25-to-30-hp-part-2-a-25933.html and I thought I could of done the same but I guess not.

 

[Faztbullet]

Not on this motor.....

 

[flyingscott]

Well I know some 25hp requires a simple gasket and timing change like in this link http://www.rib.net/forum/f36/uprating-mariner-25-to-30-hp-part-2-a-25933.html and I thought I could of done the same but I guess not.[/QUOTE
That is a tohatsu motor that is not what the OP has. The OP has a Mercury built and designed motor NOT the same.