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.
 
boggybrn said:
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...
Click to expand...

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
 
prv said:
I can't really confirm it, but it does match my understanding.
Click to expand...

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.

____________________________
 
dylanwinter said:
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."
Click to expand...

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
 
TSB240 said:
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
Click to expand...

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.
 
C08 said:
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.
Click to expand...
The Mariner 6hp 4stroke is a single cylinder, the 2stroke is a twin, perhaps this accounts for the surprising weight difference.
 
rubbishman said:
The Mariner 6hp 4stroke is a single cylinder, the 2stroke is a twin, perhaps this accounts for the surprising weight difference.
Click to expand...

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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