2 stroke vs 4 stroke outboard

[Networker]

If you were going to buy a new outboard, say a Yamaha 9.8 2 stroke vs 4 stroke, which would you go for and why?

I have a 4 stroke that has less than 50 hours and always does. I like it when it works, but it’s rare.

Getting a new one now in Caribbean and keen to get another 4 stroke, but perhaps I’m best off with a 2 stroke? Do they go the same speed and use the same amount of gas?

Keen to learn practical pros and cons of each.


Steve

[rslifkin]

Generally 2 strokes will burn more fuel than an equivalent horsepower 4 stroke pushing the same dinghy. I'd go for a 4 stroke, and if your horsepower and weight range gives you the option of an EFI 4 stroke, do that, it'll be easier to keep it happy and working. Add a good inline fuel filter to any outboard, it'll make it easier to keep the fuel system clean and happy (small carbs have small passages that are easy to clog).

Personally, I have no desire to deal with the smoke, smell, and higher fuel burn of a 2 stroke.

[wholybee]

I would be inclined to fix whatever is wrong with your current 4 stroke.

[Ixium]

https://www.tohatsu.com/marine/na/ne..._mfs8c98c.html

They just released information about their new outboard… might be worth it to check it out.

[rslifkin]

Originally Posted by Ixium

https://www.tohatsu.com/marine/na/ne..._mfs8c98c.html

They just released information about their new outboard… might be worth it to check it out.

That is extremely welcome news! Looks like they managed to add EFI to the 8/9.8 for an extra 3 lbs. Much better than having to step up to the larger 9.9/15/20 to get it, as those are a decent bit heavier. I wonder if the 4/5/6 hp models will be next to get EFI.

[Ixium]

They have a booth at the Toronto boat show, so I’ll try and ask if they know anything when I go for a few days.

I haven’t decided on what to do between a 9.9 (or 9.8…) vs something like a 6. I’m betting the weight difference will be close to 20lb+

I have to also do a test to see about the ease of using my boom for lifting an outboard on and off…

[rslifkin]

Originally Posted by Ixium

They have a booth at the Toronto boat show, so I’ll try and ask if they know anything when I go for a few days.

I haven’t decided on what to do between a 9.9 (or 9.8…) vs something like a 6. I’m betting the weight difference will be close to 20lb+

I have to also do a test to see about the ease of using my boom for lifting an outboard on and off…

At least for Tohatsu, the lightest version of the 6hp is 55 lbs. The 8/9.8 is about 82 lbs, or 85 for the new EFI version. That weight difference is the biggest reason we currently have a 6hp on our dinghy, although I'd like a little more power. The 6hp has been reliable and does the job well though.

[Joe Okros]

Can you fix either-- 2-strokes have less to go wrong and with 2 or 3 simple precautions will run forever. (never leave fuel in them for more than a week without running it and spray the entire powerhead with a product called CRC soft seal)
Can you afford to pay to fix either-- 4-strokes need special tools/equipment to maintain/diagnose/service with commensurate costs.
What will it be attached to-- the extra weight of a 4-stroke may be an issue
How often do you replace it-- (you don't see too many 20-year-old 4-strokes)
WHO will use it (engines used by women and children don't last)
What brands are available/have dealers/ have spares/company been around for a while where you are.
What are the LOCAL regulations around 2 vs 4 stroke.
IN MY AREA--I have a small mercury/tohatsu 3.3hp for the small dink and a 15hp Yamaha or 18hp Tohatsu/mercury for the big dink. But I can, and have rebuilt all 3 at some stage--

[malbert73]

Second the EFI 4 stroke Tohatsu recommendation. 5 years on my 15hp- only preventive maintenance and otherwise flawless.
So, I suppose it could be tougher to fix than an old 2 stroke, but it also could be an “appliance” like my Toyota where no one ever needs to work on the engine and it just runs every time I need it

[Mickeyrouse]

First: nine HP is Nine HP, regardless of 2 or 4 stroke.
2nd: because a four stroke has valves and a cam shaft and other stuff, they usually weigh more. Example: my Mercury/Mariner 5 HP 2 stroke weighs 38 lbs vs a comparable 4 stroke weighing 52 lbs. May not sound like much, but when you’re using both hands to lift it to the stern rail standing up in a dinghy in a slight chop, those extra pounds are quite evident.
My 5 HP is 23 years old, having survived a two week salt water immersion. Cleaned the carb, new bearings and rings, been running ever since. With enough love, care, patience, (and money) almost anything can be made to run indefinitely.
3) 2 strokes require oil mixed in the gas, which means the plugs are prone to fouling. Carry spares.
4) carburetors need rebuild kits periodically, but complete carbs are available on ebay for about the same price as an OEM carb rebuild kit.
5) the gearing thru the lower unit may differ from two to four stroke, because the torque curves are not necessarily the same for equal-rated power. Output RPM may not be comparable two to four stroke as a result.
6)it is important to get the right pitch prop. Performance will suffer otherwise.
7) two stroke pollutes more- a LOT more, thus their sale being banned for all uses in California and I imagine other states and possibly countries.
It isn’t hard to see a time when two-stroke technology will be simply unavailable- and the parts will REALLY become hard to find.

[Kettlewell]

I recently retired a almost 20-year old Johnson 8HP 2-stroke that was the most reliable outboard I've ever owned. In the entire time I used her (a lot) the only things done were changing the lower unit oil and the plugs once or twice. Started on the first or second pull every time. However, I replaced it with a Yamaha 4HP 4-stroke, which is about the same weight. Our dink is not a fast one anyway, so the extra horsepower was not needed. The 4-stroke burns a lot less gas. In both engines I add blue StaBil 360 to every can of gas when purchased and treated fuel is the only thing that goes into the motor. Have not had carburetor problems or had to do a rebuild since I began doing this decades ago. There is always the possibiity of something plugging the low-speed jet, so learn how to clean that out. Often a shot from the skinny tube attached to a can of WD40 does the trick. At the sailing school I ran we used a lot of Yamaha four strokes and they are generally stone-cold reliable. Go all summer long with use every day and no maintenance or problems.

[westsailwill]

2 stroke Yamaha 15hp all the way, but to each their own.

[donradcliffe]

2 strokes are getting harder to find, and if you want to sell one, there will be a line of buyers.

[David Mathis]

We have a 2 stroke 1987 Evinrude 9.9 hp with hundreds, maybe thousands of hours on it. It still runs perfect with minimal maintenance. Every other year the gear grease gets changed, every five-seven years it gets new spark plugs, and about every15 years the carburetor gets a rebuild kit usually when the idle gets rough. It almost always starts first pull unless the temp gets below 50 then a second pull might be needed. It's not for sale. In 15-20 years, one of my grand kids might be writing a similar letter about it, unless gasoline has been made illegal and only electric outboards (charged by a non-polluting coal fired generating plant) are allowed.

[Madehn]

My vote is for a two stroke. Better parts availability in the islands. Easy to work on. With non ethanol gas you don’t have the issues you have here in the states. Lighter. Yes used more fuel. JMHO your boat your choice.