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Old 10-07-2019, 08:37   #1
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4 stroke or 2 stroke

I just purchased a Pacific Seacraft Flicka with a 8 horsepower 2 stoke outboard motor. It runs very well and starts first pull every time. I am thinking about replacing it with a 4 stroke Tohatsu 6 hp sail pro that I already own because the motor is about 12 years old. What advantages and disadvantages come with a 2 stroke outboard motor for motoring in salt water. I remember someone told me there were less moving parts? Anyway, thank you for your responses in advance!
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Old 10-07-2019, 08:57   #2
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Re: 4 stroke or 2 stroke

- 2 stroke has no valve train which makes it somewhat cheaper and lighter
- 2 stroke inherently have less vibration, but good modern 4 strokes are well balanced and damped so the difference isn't that great
- in those sizes each will have a carburetor
- in newer outboards each will typically have electronic ignition
- 2 stroke you have to mix oil with the gas which is a process that involves a small amount of mess and a small amount of supplies you have to carry around.
- 4 stroke you have to change the oil in the crankcase, Tohatsu recommends every 100 hours or every six months
- 4 stroke has reduced emissions and typically less stink
- Parts availability for 4 strokes can be a problem in those portions of the world where they are not sold.

Saltwater affects either design equally


I believe the Tohatsu 6hp has a integral fuel tank, which would be a convenience in many situations. I have a 4 stroke Yamaha 8hp on a my 25' Morgan and wish it had an integral fuel tank. It would give me back some cockpit space in the many situations where I'm just motoring in and out of the harbor and letting the sails do the rest.

In addition to the 4-stroke Yamaha, I have 2 stroke outboards on other boats.

There are endless discussions of which is best but in reality the differences are minor. Having a motor that is reliable, the right size with the correct gearing and prop, with the appropriate features for the situation (electric start or not, power tilt or not, tiller or remote control, integral or remote fuel) is more important.
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Old 10-07-2019, 09:26   #3
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Re: 4 stroke or 2 stroke

Jammer's summary is pretty good. In small sizes, I prefer 2-stokes. Simple and reliable in general. The small 4-stokes seem to more problem prone, especially with regard to the fuel system.
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Old 10-07-2019, 09:30   #4
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Re: 4 stroke or 2 stroke

A 4-stroke will significantly improve fuel economy. 30-50% greater range for the same fuel.

You are probably going to get the same or slightly better speed from the SailPro as that is a HighThrust model.

That also means even if both engines were 4-stroke you would be getting better fuel economy with the Tohatsu since it uses less power to get the same speed. Together the 4-stroke and HighThrust will get you 50-70% better range.

With a 4-stroke you don’t have to worry about mixing oil in the gas.

That said you do have to remember to change oil periodically and have the equipment for it.

The Tohatsu has an alternator and the 2-stroke probably doesn’t but you can check.

2-stroke are lighter for the same horsepower. These are different HP so probably weigh the same.

The 4-stroke is mechanically somewhat more complex.

2-stroke engines tend to need spark plugs cleaned or replaced at least twice as often in my experience.

I think a 2-stroke requires more frequent low level maintenance but a 4-stroke requires much more involved maintenance or repair but a lot more infrequently.

All the 2-strokes I’ve used left an oil sheen behind the boat. Not so the 4-strikes.

If you were picking a motor for a dinghy the 2-stroke would probably be the better choice if you wanted to plane.

For the mothership which is never going to plane the Tohatsu would be my choice. Range, pollution reduction and electric output are the deciding factors for me.

I actually bought one for my boat. I can’t tell you how much faster it is because most of my sailing is daysailing in a limited area and I use an electric trolling motor to get in and out. The Tohatsu is sitting in the garage until the next time I cruise some distance.
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Old 11-07-2019, 08:45   #5
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Re: 4 stroke or 2 stroke

You cannot lay a 4 stroke motor on its side, say in a locker.
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Old 11-07-2019, 08:54   #6
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Re: 4 stroke or 2 stroke

Depends on the motor. The Tohatsu I just bought can be stored on 3 of 4 sides per manual.
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Old 11-07-2019, 08:57   #7
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Re: 4 stroke or 2 stroke

We had a 6hp Tohatsu 4-stroke that worked extremely well in the temperate zone, but was a constant headache in the Caribbean. We replaced it with an 8 hp Yamaha 2-stroke, and couldn't be happier. Mixing in the oil is really a non-issue. The 4-strokes do use considerably less fuel than the 2-strokes, but frankly, dinghy fuel is a rounding error on our cruising costs.
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Old 11-07-2019, 09:17   #8
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Re: 4 stroke or 2 stroke

had a 2 stroke 3.5 tahatsu , bought a 3.5 tahatsu 4 stroke due to to many carb problems with 2 stroke . All the above insights are correct. The 4 stroke is heavier which in my opinion was an issue for me in getting it on and off the boat. Short story...started using non ethanol gas in 2 stroke and runs fine. In my perspective there is more over all power in the 2 stroke . Any one want to buy a 2 year old 4 stroke ?
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Old 11-07-2019, 09:27   #9
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Re: 4 stroke or 2 stroke

Four strokes usually weigh more than a comparably sized two stroke. Just try lifting both off the mount a few times, especially if a sea is running.

If you ever have the bad luck to drop one into saltwater or had it inundated by a following sea two strokes are definitely easier to get back to running condition.
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Old 11-07-2019, 09:30   #10
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Re: 4 stroke or 2 stroke

Do get the Tohatsu - it has extra ooomphs - better prop and longer leg. Probably the best outboard for a small craft there is.


Also el start if you want.


Google youtube Tohatsu 6hp sail version for reference and opinion.



Cheers,
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Old 11-07-2019, 10:08   #11
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Re: 4 stroke or 2 stroke

All I can add to what has been said is it's all about the weight. Two strokes are significantly lighter...hanging on your stern rail....hanging on the transome of your dink....hanging on your arm loading and unloading. I have a Yamaha 2 stoke 8 and it's the best motor I ever had. Knock on wood, hasn't needed service in 4 years now. I just run the fuel out every time I use it and it never fails to start by the second pull...even after sitting for 4 months while I am away from the boat.
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Old 11-07-2019, 10:21   #12
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Re: 4 stroke or 2 stroke

Quote:
Originally Posted by stewie View Post
You cannot lay a 4 stroke motor on its side, say in a locker.
Actually, yes you can.

Mine is stored tiller side down when laid on it's side.

It's a 2011 5 hp Mercury 4 stroke made by Tohatsu, but it has the integral tank which the Tohatsu 6 hp does not

It's the main engine for my boat a 6600 lb Bristol 27. When not in use or for maintenance I mount it on the stern railing.

It weighs 57 pounds and I can reach over the stern rail, raise it to the top manually so far, and mount it there.
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Old 11-07-2019, 14:03   #13
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Re: 4 stroke or 2 stroke

Quote:
Originally Posted by barnakiel View Post
Do get the Tohatsu - it has extra ooomphs - better prop and longer leg. Probably the best outboard for a small craft there is.


Also el start if you want.


Google youtube Tohatsu 6hp sail version for reference and opinion.



Cheers,
b.
I have a Tohatsu 8 hp 2 stroke. Vintage 2002. What a work horse. It doesn't quit. It is lighter than a comparable 4 stroke, a big advantage for me since I am handling it often by myself. It gets up plane very easily. I will keep it until it dies. A major OB dealer in Annapolis, when I asked him if he thought I should trade in my stroke for a 4 told me to absolutely not do it. He said he can't keep used 2 strokes in stock.
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Old 11-07-2019, 15:10   #14
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Re: 4 stroke or 2 stroke

I have had both. A 9.8 Tohatsu 4 stoke (ran perfect always!), and a 15 Yamaha 2 stroke. Both are within a pound of each other. The Yamaha as almost as quiet as the Tohatsu, and almost zero smoke with the 100:1 oil mix.

I prefer the 2 stroke.
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Old 11-07-2019, 15:12   #15
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Re: 4 stroke or 2 stroke

I have the hi thrust Tohatsu extra long shaft 6 HP 4 cycle. Yesterday we cranked up 5 knots pushing our 5000 lb oday 25 while also towing an Ideal 18 foot (no engine) keel boat . All due to no wind. No problem with only 6 HP
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