Mercury 60 4S

**slowJEEP** · 02-02-2023, 02:23 PM

Mercury and Yamaha share an odd amount of similarity between their 30-60 hp 4 stroke motors. I don't know who did the original design work but they obviously shared. The Yamaha 30-40 is similar to the Mercury 3 cyl 40 and the same goes for the yamaha 50/60 and Mercury 4 cyl 40/50/60.

I've started to reverse engineer the merc motors to get an idea of what they need to make more power. The links below are documentation of some of my findings. It's been a little while since I messed with them but they're back on the front burner. I'll update this post with findings as they come.

Microsquirt Merc 60 4S
https://www.crackerbaythundercats.co...fi-merc-60-4s/

Merc 60 4S OE
https://www.crackerbaythundercats.co...y-60-4-stroke/

If you know something about making these motors faster, post it on up.

**DanUmbarger** · 02-02-2023, 03:31 PM

If I remember correctly back in the beginning of the 4 stroke craze Mercury and Yamaha were in bed together...Mercury designed the 25 HP and Yamaha designed the 50HP so when they split I'm sure they both used what was best in their eyes.

**slowJEEP** · 02-03-2023, 09:52 AM

Makes sense and they've teamed up several times before so I guess it isn't a surprise.

**Capt j** · 02-04-2023, 08:28 AM

The Mercury 40 hp is made by Yamaha and same specs as the Yamaha 30/40. Not sure on the next size up in HP, who makes what for who.

**slowJEEP** · 02-04-2023, 10:38 PM

I saw the 30/40 yamaha shares the sams specs as the 3 cylinder merc 40. I would have imagined the merc 747cc 40 is made in China just like the 1 liter mercs. Where did you see Yamaha made those motors for merc?

Originally Posted by Capt j

The Mercury 40 hp is made by Yamaha and same specs as the Yamaha 30/40. Not sure on the next size up in HP, who makes what for who.

**Capt j** · 02-04-2023, 11:51 PM

Originally Posted by slowJEEP

I saw the 30/40 yamaha shares the sams specs as the 3 cylinder merc 40. I would have imagined the merc 747cc 40 is made in China just like the 1 liter mercs. Where did you see Yamaha made those motors for merc?

A Yamaha/Mercury dealer that had a 30hp Yamaha and a 40hp Mercury in his shop, The 25hp Mercury is different but the same as 30hp Mercury (only ECM is different between the 2).

**derekfl** · 03-30-2023, 06:41 PM

and do ecm swaps work? i hear the diff between a 50 and 60 big foot is a restrictor plate and ecm. and you see aftermarket chips promising 15% more with more aggressive less emissions-minded fuel and ignition map. or can one get their existing ecm reprogrammed?

**slowJEEP** · 03-31-2023, 08:38 AM

Originally Posted by derekfl

and do ecm swaps work? i hear the diff between a 50 and 60 big foot is a restrictor plate and ecm. and you see aftermarket chips promising 15% more with more aggressive less emissions-minded fuel and ignition map. or can one get their existing ecm reprogrammed?

According to the parts diagram at boats.net, there's a restrictor for the 40 and 50 and none for the 60. While they all use the same throttle body.

**slowJEEP** · 04-03-2023, 09:30 AM

Originally Posted by Capt j

A Yamaha/Mercury dealer that had a 30hp Yamaha and a 40hp Mercury in his shop, The 25hp Mercury is different but the same as 30hp Mercury (only ECM is different between the 2).

Sounds like they're similar enough design but when you say Yamaha made the Merc 40 I assumed you meant Yamaha physically produced them. If that were the case, they'd say made in Japan, France or Brazil in one of their 4 factories spread over the 3 countries. And they do not.

The 3 cylinder and the 4 cylinder, practically speaking, only differ by cylinder quantity. So I would say the designer of the 747cc 3 cylinder had a lot to do with the design of the 1L 4 cylinder. Maybe they shared workload and designed certain parts of each motor. I wish I knew who to ask, just out of curiosity.

**Capt j** · 04-03-2023, 10:31 PM

Originally Posted by slowJEEP

Sounds like they're similar enough design but when you say Yamaha made the Merc 40 I assumed you meant Yamaha physically produced them. If that were the case, they'd say made in Japan, France or Brazil in one of their 4 factories spread over the 3 countries. And they do not.

The 3 cylinder and the 4 cylinder, practically speaking, only differ by cylinder quantity. So I would say the designer of the 747cc 3 cylinder had a lot to do with the design of the 1L 4 cylinder. Maybe they shared workload and designed certain parts of each motor. I wish I knew who to ask, just out of curiosity.

The 30+40hp Yamaha 4 stroke, shares the EXACT same specs as the 40HP Mercury. They're the same motor. Yamaha makes it.
The 25+30HP Mercury share the same specs............Mercury could get away with an ECM change on the 25hp to make 30HP.
The 50/60/75HP Mercury shares the same motor, mercury didn't bother making a 40hp.

**slowJEEP** · 04-04-2023, 08:46 AM

Correlation is not causation. Since the dawn of the industrial revolution, mankind has been able to produce parts in different locations that go together. Yamaha could build parts that are the exact same as the one Mercury builds. They are the same, yet produced by different manufacturers. Your statement is equivalent to saying that all #2 Philips head screw drivers with a 6" shaft and a black and hellow handle are built by Stanley because that's what Stanley builds.

The real reason it matters can be seen in the case study of a transmission simultaneously produced by Ford and Mazda for their small pickup trucks. They both had the same drawing package but the Mazda (Japan) produced transmissions lasted longer than the Ford (USA?) built transmissions. It was determined that the difference was the actual machinists. The Japanese machinists strived for perfect regardless of the tolerance given on the drawing. The Ford machinists were satisfied with anything within tolerance. The design was such that a transmission built closer to nominal dimensions had a longer service life.

Sorry for the argumentative stance. I don't have any technical updates on this project and lack something better to do.

**slowJEEP** · 04-04-2023, 08:58 AM

Originally Posted by Capt j

The 30+40hp Yamaha 4 stroke, shares the EXACT same specs as the 40HP Mercury. They're the same motor. Yamaha makes it.
The 25+30HP Mercury share the same specs............Mercury could get away with an ECM change on the 25hp to make 30HP.
The 50/60/75HP Mercury shares the same motor, mercury didn't bother making a 40hp.

Mercury sells a 40/50/60 1L 4 stroke. They also sell the 747cc 40 4 stroke. The 75 is a 2.1L and is also used for the 90 and 115 models.

Yamaha as the 30/40 747cc motor and 50/60/70 1L. The 70 is the 4 valve head but the 50/60 have the same 2 valve head as the merc.

**FMP** · 04-04-2023, 11:57 AM

I'm guessing nobody has done anything internal, get the cr up , improve head flow, cam change?

**slowJEEP** · 04-04-2023, 12:06 PM

Originally Posted by FMP

I'm guessing nobody has done anything internal, get the cr up , improve head flow, cam change?

Yeah, that's all been done. I know of one person besides myself that's worked on swapping the computer. Without doing so, you're leaving a lot on the table.

Working now on identifying alternative rods and pistons in addition to some crank modifications to improve the 1.5:1 rod ratio which us killing rod bearings and piston skirts.