2 stroke to a 4 stroke?

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nytebyte

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I have a 20hp Mariner on a Lund 14' now and I am thinking of going to a 4 stroke 20 Suzuki or Tahatsu. With this boat set up the way I like it now I get 23 mph. Plenty for me. Question is would I lose anything by going to a 4 stroke? To me a 20 is a 20 but I've heard the 4 strokes don't have the power? Thanks, Jim
 
The 4 stroke will be heavier. If everything else is the same, you will lose a bit of top end speed due to the extra weight. Your gas mileage will improve, and your wallet will be lighter for the money you spent on a new motor.
 
Be a little heavier. Top speed should be very close but the two stroke will eat the four strokes lunch getting up on plane. But either the four, you’ll have money left for lunch at the gas station and it’s quieter, nice especially if you troll a lot.


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No idea what my Mariner weighs but I see the Suzuki is advertised at 97# and I should be able to get by on a 3 gallon tank rather than the 6 My mariner takes. Always like to start with a full tank even if I don't need it LOL. That should make up for the weight change. Mostly interested in the power. I like the idea of the quite 4 stroke. Not sure which motor is the better of the 2. I don't see many of either in the waters I fish. Mostly Mercs and Yamahas around here.
 
You need to check out the new Mercury 20 hp 4 stroke. It's built by Tohatsu so its light weight but it has a lot of interesting features.
 
You will lose some speed due to the motor being heavier However the four stroke should be A lot quieter than the 2 stroke. If you're worried about it step it up and get a bigger 4 stroke

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Just found the specs on my motor online. The 1988 mariner 20hp is 107# so the Suzuki is 10# lighter. Still cant decide. 30 years old and no problems. Wonder if I can get that out of a new 4 stroke. There isn't anything wrong with it now but I would like something quiet and maybe electric start. Getting older and not so easy to pull over. As far as a starting battery a motorcycle one would work and they are not all that heavy so that extra weight would make it about the same as the Mariner. Figure if it will start my Goldwing it would start a small 20 hp outboard. Just looked it up and see the Suzuki 20 with electric start is 106# so real close to the Mariner.
 
Your old motor still works good, so it can get good price on used market.

10 years from now you will be glad you made the change.

It won't get any cheaper.
 
On a smaller motor, it may not be as much of an issue, but when I bought my new electric start 35hp Tohatsu a year ago, I was warned about using too small a battery to start it. The electronics in new motors are pretty sophisticated and require strong steady power. Check with your dealer and manufacturer to see what size battery to use. You wouldn’t want to fry the computer in a new motor.
As an older guy myself, electric start was a requirement for me as well as power trim. Trying to pull start a 20hp or bigger 4 stroke is not something you want to do frequently. If you are going to repower, don’t try and save a few dollars by not buying the biggest motor your hull will allow. For resale value alone, a bigger motor makes it much easier to resell.
 
The new 20 hp Mercury, Suzuki and Tohatsu are all as light or lighter than a lot of the old 2strokes. They also are fuel injected so they should start easier, run better, quieter, maybe faster than the old 2smokes. Things have changed in the last couple years.
 
That's what I was thinking and hopeing. Faster or at least as fast and lighter. Like the idea of not having to mix fuel and the quite of the 4stroke. Would be nice if the dependability was there to. Anyone change to a 4 with the same horsepower as the 2 stroke? How did it do?
 
I had a Yamaha 15hp 4 stroke on a previous boat, and a slightly older Yamaha 2 stroke on my last boat so a good comparison I think.
Well the 4 was quieter and had a very very smooth idol but was almost twice the cowling size, but the 2 stroke was a revvy little thing, light on the tingyness but amazing pick up and flat out speed.
I have to say I preferred the two stroke, mixing fuel is no drama and they are simple and reliable motors.

Although all motors will be 4 stroke soon, even chainsaws and the like.
 
Probably going to wait and see how I come out on taxes this year. Wish I could do like a car and try it out first LOL. The Suzuki has been out for awhile and seems to have proven itself where the Tahatsu is just now going to EFI so If all goes well I think I will go with the Suzuki. Thanks for the info. Jim
 
In the older 2 strokes, 20hp usually share the same platform as 25 and 30 hp engines. In the newer 4 strokes it’s mostly
15-20 and 25-30 that share. You would probably not have much if any weight penalty. The new motors are nice. In your case, it’s a win. Quiet, smooth, fuel efficient. As for long term reliability, time will tell. The 1983 Johnson 35 that I run has few moving parts and simple electronics. Runs great and I trust it enough for interior camping/fishing trips in Canada. A new Suzuki 30 hp costs 6 grand and weighs 50 lbs more, so I’ll be sticking with the old one for a while. If I was running a 20 and not looking to upgrade power, I’d be taking a hard look at that Suzuki if there is a good dealer close to you. Happy fishing either way you decide.


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That's one of the things holding me back-no local dealer. If I go the new Suzuki route it will probably be with Online Outboards (Cumberland) and take my chances that nothing goes wrong. The normal maintenance I can handle I think but other than that I would just have to hope for the best.
 
The weight is a non-issue in all honesty. Guys are so afraid of 10 lbs it's just funny. BUT that said, watch the weights of the 4 stroke stuff because, well basically the newer the motor the lighter it is. Some of the older stuff are heavy pigs.

You won't see any decrease in top speed to speak of, at least not with a Tohatsu/Merc/Nissan. All the same motor, rebadged. I hate the way Mercury does that...can they not build their own small 4 stroke motor? Speaks volumes, in my opinion. Also, I am told that a new 15 and 20 Yamaha will be introduced at some point. They're secretive. Could be tomorrow. Could be 5 years from now. The current 15/20 are the same exact motor with minor differences making up the 5hp, same weight everything. Great motor. Sold hundreds, never seen one back for anything but an oil change or carb cleaning (sitting without use for long length of time).

Yes, with a 4 stroke, 3 gallons lasts a LONG time. I have a 25 and I've yet to run 3 gallons of fuel through it in the 6 years I've owned it. Not on a single outing anyway. I have run as far as about 22 miles upriver, full throttle 99% of the time, drift back, do it again and after loading, was down about 2 gallons (1 gal left). Pretty impressed with the lack of fuel usage.

Maintenance is no big deal. Beats forgetting to premix for sure; along with the other perks of the 4 stroke stuff.

There was a long post about Suzuki on this forum. Might search for it....that poster and several others locally have NOT been impressed with them. And locally, zero support for 'em. One dealer in the entire state and they may not even deal with them now.
 

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