Mercury, Mariner and Tohatsu 5/6hp

Probably, and not just the 5-6hp. It's pretty long-standing. My Mercury 3.3 (2-stroke, although I hesitate to admit that to you) is a re-badged Tohatsu 3.5. There are detail differences, mostly for the better, presumably specified by the client.
 
My understanding is that the 4, 5 & 6 HP engines are all the same apart from the carburetor.
I just got a 4hp Tohatsu with a boat I bought. I'm hoping someone here can confirm or deny what I just wrote, before I splash out on a 6hp carb...
 
Not many years ago just about all small outboards were built by Tohatsu and then badged for the resellers!

Extra hp is down to carb jetting
 
A few years ago, just before the 2 strokes were discontinued, I was in the market for a mariner 4hp sail drive. I was told by a dealer the only difference between the brands was the paint. Mercury and Mariner were harder wearing. I was also told that he could re-jet a 4hp Tohatsu to make it a 5hp. I still opted for the Mariner 4 sail drive with its high thrust prop.

I don't know anything about the current models, but models have been shared across the brands for years. I have a 1995 Mariner 40hp on a rib. If I need spares it is easier to get them from a Mercury dealer as the model I have was just after Mariner had started rebadging Mercury engines rather than Yamaha.
 
My understanding is that the 4, 5 & 6 HP engines are all the same apart from the carburetor.
I just got a 4hp Tohatsu with a boat I bought. I'm hoping someone here can confirm or deny what I just wrote, before I splash out on a 6hp carb...

I can't really confirm it, but it does match my understanding.

I have a 4hp Johnson, which is unusual in that it's a beefed-up 2 / 3 hp rather than a cut-down 5 / 6, and therefore significantly lighter than any other 4hp motor.

Pete
 
I can't really confirm it, but it does match my understanding.

Mine too.

They all seem to use the same 123cc power head for the 4/5/6 hp versions.

One difference is the saildrive for the Tohatsu is 6hp but it is only available as 5hp on the Mariner and Mercury. That's why I've just got a cheap Tohatsu for my Jag 24 as it needs that extra little bit of grunt.

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Is this statement true?

"Mercury, Mariner and Tohatsu at this size are all the same engine.

The only difference between a 5 and 6 is the rev range, its how they get the extra hp."

This is true if you look at the specificatons........ But in order to achieve that they are probably using a combination of either restriction at the carb venturi or jetting and or electronic rev limiting.

I spent a rainy afternoon interrogating the online parts lists and looking for differences between the Totty 6, 8 and 9.8 hp two strokes. 6 to 8 is a jet change, 8 to 9.8 "appeared to be" both a new carb and power head on later models. I remain to be convinced of any major powerhead difference without actually having one dismantled and sectioned!

The later Johnnyrudes 5, 6 8, hp twins were similar 5 and 6 in fact had no different parts in the build except for a decal or two! I have just ordered a set of 6 Hp ones.

The 8 had a different carb and jets.

I have not bothered with the same research on single cylinder 4 strokes as in my opinion they are the devils spawn!

Waiting for incoming from D

Steve
 
I have not bothered with the same research on single cylinder 4 strokes as in my opinion they are the devils spawn! Waiting for incoming from D. Steve

Certainly I found the Suzuki 4 stroke DF6 to be rubbish. Was told by the dealer that the only difference between the DF 4, 5 & 6 was rev limiting by the ignition module.
 
I was looking at a 6hp Tohatsu 2 stroke engine and was surprised that the 6hp 4 stroke is a very similar weight.The reason is apparent when you look at photos i.e. the 6hp 2 stroke is clearly heavier built than the 4 stroke 6hp. In fact the 6, 8 and 9.8 2 strokes are all the same engine. The 4 and 5 hp 2 strokes are the same engine. The 6hp 4 stroke is I think the same engine as the 4 and 5hp.
 
I increased the HP of my Tohatsu 2 stroke from 2.5 to 3.5. It took about ten minutes. You simply remove the sliding barrel from the carb and removed 7mm from it with a hacksaw. This enables it to open fully within the carb throat whereas before it only opened about 2/3 of the throat to air flow. There's plenty written about the procedure on the web.
 
I was looking at a 6hp Tohatsu 2 stroke engine and was surprised that the 6hp 4 stroke is a very similar weight.The reason is apparent when you look at photos i.e. the 6hp 2 stroke is clearly heavier built than the 4 stroke 6hp. In fact the 6, 8 and 9.8 2 strokes are all the same engine. The 4 and 5 hp 2 strokes are the same engine. The 6hp 4 stroke is I think the same engine as the 4 and 5hp.
The Mariner 6hp 4stroke is a single cylinder, the 2stroke is a twin, perhaps this accounts for the surprising weight difference.
 
The Mariner 6hp 4stroke is a single cylinder, the 2stroke is a twin, perhaps this accounts for the surprising weight difference.

Good point. That explains why the 6hp 4T is an upgraded 4hp and the 6hp 2T is a downgraded 9.8hp and the weight discrepancies.
 
are you trying to tell me that instead of going out and getting a 40hp for my boat , I could have mucked about with the carb on my 8hp tohatsu and turned it onto a whopping 9.8 !!:p why does this info always appear after I spend money :disgust: ..
 
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