2 stroke vs 4 stroke

[bison716]

I currently have a '93 - 15 hp Johnson that I'm having issues with, and it's mounted on a 12' Inflatable that has a max rating of 15 hp. When the engine was running normally, it had lots of power with my wife and I in the boat, in fact full throttle is too much and the boat starts to wander a bit. Now I'm tired of fixing and ready for a new or near new motor. Weight is a big issue as I lift it on and off the boat each time we go out. Based on the 15 hp performance, I think a 9.9 hp would be enough. The new 9.9 four strokes are fairly light, but my question is will it have enough power? Or do I need to stay with a 2 stroke? The 15 hp 4 strokes are just too heavy and out of the question. I'm not sure how performance compares size for size of 2 stroke vs 4 stroke. Would appreciate any advise. Thanks.

 

[choppermn27]

Re: 2 stroke vs 4 stroke

10HP should be plenty of power for a 12 foot light boat.
With 2 strokes you get more power with a lighter motor, but usually are not as fuel effecient. I'd say go with a newer 2 stroke, but I'm biased and stubborn, and love 2 strokes, even though they tick me off all the time.

 

[jtexas]

Re: 2 stroke vs 4 stroke

With a 4 stroke, each piston makes power on every 2nd revolution; 2-stroke pistons are making power every time they go around. means better acceleration.

4-strokes have more than twice as many moving parts.

But none of that really matters. What matters is, what's more important to you...

If it's fuel economy, get a 4-stroke.

If it's power-to-weight ratio, get a 2-stroke.

If you're concerned about the environment, there are ways to make up for it -- make your wife drive a hybrid, or use a reel-type lawn mower.

 

[d.boat]

Re: 2 stroke vs 4 stroke

Why not try to rent or borrow a 10 hp 4 stroke?

Weight for me is a major factor as well and I really like my '70s Merc 9.8 which I think is an exceptionally light and powerful example of the "10 HP" range of 2 strokes.

 

[old boat 54]

Re: 2 stroke vs 4 stroke

Check out the E-tec 2 stroke by Evinrude motors. Not sure how small they go in h.p. but they are injected, and have good fuel economy. A lot less parts then 4 stroker.

 

[bison716]

Re: 2 stroke vs 4 stroke

Thanks for the information. I am leaning towards a 2 stroke as well. I'm not concerned about emissions or fuel mileage. A couple of factors that make this decision tougher - a new 4 stroke is actually less expensive than a 2 stroke (go figure) plus a few of our National Parks up here in Canada have outlawed 2 stroke outboards. I hope this is not a growing trend, but I don't want to limit the lakes I can visit. I thought buying a new outboard would be easy but it's not!!! My question is if anyone can tell me if a 9.9 hp in a 4 stroke will perform as well as a 9.9 hp in a 2 stroke version. If it's only slower to get up on plane and the top speed ends up as the same, I can live with that. If not, then I must stay with a 2 stroke. Thanks for any advise.

 

[Jerry_NJ]

Re: 2 stroke vs 4 stroke

I think the 4 stroke is just slower "out of the hole"... getting going, less torque/power at ramp-up or RPM. I guess the RPM comes up fast anyway, the prop just slips.

I have owned only 2 stroke so I don't speak from first-hand experience.

For me the next engine will be a 4 stroke (that may soon be all that is available on the new market - that may be the case today in the USA, I don't see 2 strokes in my favorite general catalogs: Bass Pro and Cabelas).

It is my guess that in the USA 2 strokes will remain "grandfathered" and allowed on our lakes - but who knows, who would have guess the long reaching and extensive new laws that our federal government has passed in the last 18 months?

Enjoy, I will also guess the 4 stroke smells better and may be quieter.

 

[HighTrim]

Re: 2 stroke vs 4 stroke

Enjoy, I will also guess the 4 stroke smells better and may be quieter.

Bah, I love the smell of a well tuned 2 stroke in the morning!

 

[wilde1j]

Re: 2 stroke vs 4 stroke

Check out the E-tec 2 stroke by Evinrude motors. Not sure how small they go in h.p. but they are injected, and have good fuel economy. A lot less parts then 4 stroker.

25 HP is the smallest, and the small E-Tecs are seriously heavy.

 

[jtexas]

Re: 2 stroke vs 4 stroke

Valve train and oil sump add weight to the 4-stroke, so all else being equal, if the actual horsepower output is really the same, the heavier 4-stroke has to be slower on the same boat. Maybe noticeably slower. In my experience, the smaller the boat, the more impact from each added pound. How much speed loss can you tolerate?

But this is all theoretical; any given 4-stroke might weigh more or less than a 2-stroke of different make/year. Actual results may vary.

... It is my guess that in the USA 2 strokes will remain "grandfathered" and allowed on our lakes - but who knows, who would have guess the long reaching and extensive new laws that our federal government has passed in the last 18 months? ...

I predict the mandated ethanol content of gasoline will pretty much render all our current motors obsolete, and that will happen before existing 2-strokes are forced off the water by regulation.