What hp 4 stroke should I look at to replace a 1985 evinrude 20 hp 2 stroke. 14 ft crestliner muskie aluminum boat

[ab59]

I bought this 1986 Crestliner 14' v hull muskie model boat with a 20 hp Evinrude 2 stroke motor on it. Although I have replaced a few things on the motor and it runs pretty good, I just want to get rid of the smoking slobbering motor and replace it with a 4-stroke. The weight difference and power differences of the two different motors escape me except that the 4-stroke is much heavier. The 20hp evinrude on the boat now seems to be a little taxed to get the boat up on plane but I'm not sure that I get full power from it. The specs for the boat say that it can take a 35 hp motor but I'm thinking that a 4-stroke that size would be too heavy for the boat. A 25 hp seems to be a good trade off but again I'm not sure about the weight problem. The boat is fairly heavy for a small aluminum boat so I'm just not sure of what to look for. Advice from those who know would be appreciated!! thanks-
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[RMClark]

The Crestliner Catalog for 1986 shows a base weight for your boat of ~390 pounds. Further, the Crestliner Catalog says that your boat's max weight capacity is 770 pounds if it has the 15" transom; 925 pounds if it has the 20" transom. Max capacity is usually based on weight of people + motor + gear.

If it was me, and it's not, but if it was me, I'd like to get as much motor as I can based on max HP rating for the boat, and the people and gear that I would carry in the boat. That gear includes fuel, passengers, fishing tackle, stuff, plus the weight of any modifications that have been made to the boat.

Presuming the transom is solid, look on the identiplate for max weight capacity of the boat. To me, the identiplate trumps the catalog in terms of reliable information, so look for that number on your identiplate.

Max HP for your boat is 35 HP. Find the weight of the 35 HP motor of your choice. Subtract that number from max weight capacity to find what I'll call payload capacity. Can you carry all you normally want with you in that number? If not, you might need to start trading motor size to free up weight.

For my Lund, the maximum capacity is 895 pounds (people + motor + gear.) I allow 400 pounds for two fisherman, my add-on decks weigh about 100 pounds, full fuel tank weighs about 25 pounds, trolling motor weighs about 50 pounds, batteries weigh 65 pounds total, other gear weighs about 75 pounds. That's 715 pounds. My 20 HP Merc four stroke weighs about 125 pounds. All of it totals 850 pounds, which gives me a margin of 45 pounds for added gear or a heavier fisherman. If we added a third passenger, I'd have to leave some gear behind to stay under maximum weight.

 

[ab59]

The Crestliner Catalog for 1986 shows a base weight for your boat of ~390 pounds. Further, the Crestliner Catalog says that your boat's max weight capacity is 770 pounds if it has the 15" transom; 925 pounds if it has the 20" transom. Max capacity is usually based on weight of people + motor + gear.

If it was me, and it's not, but if it was me, I'd like to get as much motor as I can based on max HP rating for the boat, and the people and gear that I would carry in the boat. That gear includes fuel, passengers, fishing tackle, stuff, plus the weight of any modifications that have been made to the boat.

Presuming the transom is solid, look on the identiplate for max weight capacity of the boat. To me, the identiplate trumps the catalog in terms of reliable information, so look for that number on your identiplate.

Max HP for your boat is 35 HP. Find the weight of the 35 HP motor of your choice. Subtract that number from max weight capacity to find what I'll call payload capacity. Can you carry all you normally want with you in that number? If not, you might need to start trading motor size to free up weight.

For my Lund, the maximum capacity is 895 pounds (people + motor + gear.) I allow 400 pounds for two fisherman, my add-on decks weigh about 100 pounds, full fuel tank weighs about 25 pounds, trolling motor weighs about 50 pounds, batteries weigh 65 pounds total, other gear weighs about 75 pounds. That's 715 pounds. My 20 HP Merc four stroke weighs about 125 pounds. All of it totals 850 pounds, which gives me a margin of 45 pounds for added gear or a heavier fisherman. If we added a third passenger, I'd have to leave some gear behind to stay under maximum weight.

Great, using your formula and subtracting the casting decks, I come up with around 725 lbs if I run a 135lb 25 hp merc. that is of course is with a 4 stroke. I am running Lithium batteries so my trolling motor with the single battery that I use is around 65 lbs total. Funny, I bought a Lithium 20 amp hour battery that weighs about 4 lbs to run my electronics and it lasts for days. There is a lot of different information floating around the internet and it can be a little confusing. Thanks for your input, I will look for a 20 to 25hp 4 stroke and figure that It's the best for what I have. Thanks again and thanks for your reply. It helped.

 

[airshot]

Do you care about speed ? A 20 hp 4 stroke will be a little slower than a two stroke, in order to maintain your current performance, you would probably need to go to at least a 25 hp 4 stroke..

 

[RMClark]

A 30HP Merc weighs about 145 pounds dry, according to their web site. So weight would not have been the driver for me. 20 pounds difference is easy to accommodate.

For me, that 20HP point is where budget became a factor for the new motor.

When I was pricing motors, I found out that Merc includes prop, external fuel tank, and fuel line with the 20 HP. Anything bigger than that and those items were extra. Given that motors seemed to run about $150 for every 1 HP of power in that size class, I couldn't justify the added cost, particularly since so many of the lakes around me are no-wake lakes. Even the unrestricted lakes aren't that big, and my boat is not suitable for really big water.

As it is, I can get 23 mph out of that 20HP fully loaded.

 

[matt167]

Suzuki are the lightest for their hp. I’d get a DF25A or DF30. Same motor different ecu and 25hp is restricted. Small Mercury is just a black Tohatsu

 

[909]

You should stick to a 2 stroke and get a 3 carb 35 HP Johnson / Evinrude as new as possible from the 2000's.

Properly maintained 2 strokes do not smoke or slobber running synthetic.

 

[racerone]

I would refresh / rebuild the 20 HP.-----Set it up properly and use a good oil.

 

[racerone]

While working on this wonderful 20 HP 2 stroke you could bump it up to 30 HP with small investment in parts.----Then of course if you have the beer tokens to buy a new 4 stroke , you do not have any issues.

 

[QBhoy]

I’d stick to a good 2 stroke personally. Unless you have money to burn on a financially silly purchase of a nearly or new merc model (eye watering to buy though and you’ll never get your money back if you sell her on), the earlier and less expensive 4 strokes are just rubbish. Get yourself a nice 30hp Yamaha or merc 2 stroke.

 

[ab59]

Lol, I got busy and forgot about this thread. I don't care about speed so much as long as the motor will plain the boat out. I don't trust 2-stroke injected motors, the injection systems have caused a lot of cratered motors. I do not like the smoking, slobbering nature of pre-mix motors. The ability to idle and the gas-stingy nature of a newer 4-stroke are what I am interested in. That said, I'm not a rich man so am carefully looking for a late model that I can buy for around 2 thousand. And for that, I'm looking for one with not many hours on it. lol. I will find one sooner or later. In the meantime, I will use what I have. Guess I will have to install the carburetor rebuild kit I bought for it soon. Time is fleeting as you all know. Will work it in somehow.

 

[ab59]

While working on this wonderful 20 HP 2 stroke you could bump it up to 30 HP with small investment in parts.----Then of course if you have the beer tokens to buy a new 4 stroke , you do not have any issues.

It's funny, I saw a youtube clip about changing out the manifold and carburetor for a 35hp of the same era to make the 35. I don't think I'm willing to spend much more on this old motor. Interesting idea though.

 

[matt167]

Couple years ago when I looked into it, it was just a couple hundred in parts to go from 20-35hp

 

[ab59]

I have been kinda keeping an eye out for a 35hp of the 1985 era but people locally seem to want a small fortune for these old motors. Seems like 750 for a junk motor is common. I don't know who would ever buy one for that kind of money, but I am sure not interested. I will make due until I find a good 4-stroke.

 

[matt167]

Fwiw the 30hp and 35hp are the same. It’s a crank vs prop rating that changed in 1986 if I remember right. You could do 25hp with just the carb I think

 

[airshot]

I have been kinda keeping an eye out for a 35hp of the 1985 era but people locally seem to want a small fortune for these old motors. Seems like 750 for a junk motor is common. I don't know who would ever buy one for that kind of money, but I am sure not interested. I will make due until I find a good 4-stroke.

I paid 1200 for a mint condition 40 Johnson 2 stroke, ran great, sure was a lot cheaper than 4500 for a 4 stroke and faster as well. Last year I bought a boat with 2 stroke, 4 cylinder Merc 40 hp, awesome engine, idles smooth down to a crawl, oil injected so only smoke on initial startup... Much easier on fuel than my 40 hp Johnson by a long shot....and much quieter !!