Yamaha 4hp 4 stroke

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m1taylor

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Probably been asked many times before, buried in lots of posts. Any views on this engine? I have sold my brute of a seagull (sad day), and was thinking of a second hand yamaha f4 as it seems to be quite light (22 kilos), and one of the few 4HP models that can have an external 12 litres tank.
 
Had one which I used for a couple of years as propulsion for my tinker, with a 12litre tank in the bow, and as an auxiliary on my 17' fishing dory. Great engine, but make sure to try and keep it upright, as it didn't seem to matter which way I laid it down, the oil filled the cylinder in no time! Always made sure to carry a plug spanner, spare plug and oil, if I was transporting it in the car...
 
I have one and it is a great motor. Much better than the Honda 5hp I had before. I added an extended gearlever which makes selecting gears (and neutral, more importantly) much, much easier.

Outboardgearlever2.jpg
 
Had two of the little buggers - changed back to 2-t mercury 3.5.

Too heavy for manhandling on and off the tenders, had to be kept upright or laid down a particular way. starting problems (SHMO and the kids had problems)

While 2-ts are available I will keep away from 4-ts.

Still some good deals on tohatsus
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I like mine. It only doesn't start 1st pull if i havent squeezed the fuel bulb, and there is no fuel in the carb. I picked it over the others because it can have an external tank, ( mine is 25L), I've only ran it for 10 - 15 hrs, so its only just ran in, but so far im happy with it
 
Have had one on another boat, great motor.
Now have the 2.5hp version for tender.
Any of the four stk outboards will take oil in through the rocker cover breather to the cylinder if placed with the rocker cover side faced down, even the small generaters will do same, I know cause I used to be a plant fitter.
As said always place them with the front, ( forward) side down and there wont be any problems.
I dont recommend the honda's, lots of problems reported.
 
I'm confused-you say always place them "front side down", yet LakeSailor says "Tillerside down".
Am I missing something here?
 
I just follow the very explicit recommendations in the handbook and on the sticker on the motor. Works for me.
It rarely starts 1st pull. I use the internal tank and I reckon the bobbing on the mooring spews a little fuel out of the carb. Thus a couple of long, steady pulls required to fire up. Only use a bit of choke and push it in straight away.
Quiet under way and steady tickover when piddling about mooring. Never need even half throttle to shift my 18ft boat.
 
I was told when I bought mine that because the carb is mounted high up on the engine, it was inclined to drain when not in use. So a couple of long steady pulls to refill it, and then away it goes.

I've found that opening the fuel cock before opening the air vent overcomes this - I suspect the slight pressure in the sealed tank is sufficient to refill the carb.

Bloody heavy engine after the 2 stroke version
 
That's a good idea. Bit like pressurised priming. It is heavy compared to a 2 stroke, but I use in on the stern of a yacht so it only gets moved maybe a couple of times per year.
 
I am not sure I understand this 'heavy' business. Yamaha state that its 22 kilos. Now the 2 stroke 4hp mariner, and the similar 4hp 2 stroke Tohatsu are also 22kilos plus? So yea, sure, it's heavier than a Tohatsu 3.5hp, or a Marina 3.3, but actually on paper no different in weight from the latest 4hp 2 strokes. So when people say 'heavy' - heavy compared to ...
 
Good point, but I stopped arguing that one ages ago as people have the impression that because a 2 stroke has twice as many firing strokes that it's HPs are more powerful than a 4 strokes HPs. So a 2 stroke 3.3 or 3.5HP is apparently more powerful than a 4 stroke 4 or 5HP.

No, I don't follow it either.
 
Around 14kg for the Tohatsu 3.5 or Merc 3.3 2t vs around 22Kg for the 4hp 4t yam makes the yam "heavy" for SFA extra power - simple arithmetic!.
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"Artificial intelligence is no match for natural stupidity"
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Accepted - but the little Tohatsu is a dinghy engine - you'd have to refuel it every 45 mins, and the water channels are small. The build quality between a 3.5 and 4hp is quite substantial. One of the best gains is the ability to have a remote 12 litre tank. I just don't like spilling petrol in rocking boat.
 
[ QUOTE ]
Accepted - but the little Tohatsu is a dinghy engine <snip>

[/ QUOTE ]Exactly, and that is what I use them for - dinghy/tender. If the engine was permenantly mounted then I would consider a 4t but not when lifting the engine on and off the dinghy/tender.
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
Useful advice-will try that next time. The first season we had the Yam 4. 4st, we found it very tempermental to start-frequently it would start first pull so we'd go off in the tender, only to find it wouldn't restart. Last season it was much better and we felt we could rely on it to start. It certainly pushes the dinghy along very well, if not as economical as we expected.
 
Little more searching - there is a 2t 4HP which has a remote tank and is ligher than the Yamaha at just 17 kilos - the Selva 4Hp 2 stroke - still available from stock. Sounds good - but I have never heard of anyone with a selva 2 stroke?
 
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