15 4stroke vs 15hp 2stroke

[scoobeb]

I have a brand new 15hp 2stroke yamaha on a nice 14ft jon boat.It scoots pretty good.I was just wondering if i were to get a brand new 15hp 4stroke would i see a drop off in performance?I now the 4stroke is about 35lbs heavier.I'm looking at a new merc/tohatsu 15hp 4stroke.I know the yamaha is new but i think it may be time to catch up to the times.I will have no problem selling the yamaha if needed to.

The thing i want to know if i were to go with the merc,since they fixed the gear ratio in them to a 2.15 it should give it close to the same power as the 15(as far as out of the hole).My biggest thing is would i loose anything going from a 15hp 2stroke to a 15hp 4stroke besides the fact it's a lighter motor then the 4stroke.I like the idea of no mixing oil and it runs cleaner,may even get a few extra miles on a tank of gas.

Has anyone done this,go from a 2stroke to 4stroke of the same size(15hp)What was the difference?also was it worth doing?I always wanted to own a 4stroke.I may just keep the 2stroke,haven't really decided yet.But if i go 4stroke i see no need to keep both.Any help on this would be great,thanks.

 

[V8_TITAN]

if you have the money then why not ? I would have a 4 stroke on mine if I had the money. and I would go with a mercury, they seam to be doing something right. yamahas are too heavy and ive heard that they are more money in parts.

The whole no oil mixing thing is great but remember, you will have to change your oil frequently and oil filter. not sure but probably having a timing belt/ chain to worry about now also.

as far as mpg, I would bet there would be a noticeable difference in fuel consumption.

I havent seen any smaller 4 strokes run yet, but I was on a boat with a 250 suzuki 4 stroke and you can hardly even tell when its on and idling.

so if it were up to me, I would deff have a 4 stroke on my boat. If I already had a newer yamaha 15 2 stroke, I would probably keep it until its just old enough to get top dollar for it, and then go for a newer 4 stroke.

 

[DanMC]

Hi,
One thing i would never do...get a Mercury... [-o< God help you...a 4 stroke motor by Yamaha or Honda is a piece of mind future wise...and if you would want to keep up with technology....per say...ask yourself one thing :?: ...whatever you drive is a four stroke or a two stroke and then ask yourself why would i get me a "primitive" motor...go with 21 st century =D> not 19th #-o .
Dan

 

[TNtroller]

gaining 35lbs due to going 4 stroke without an increase in HP would make me think performance is going to suffer to some extent just due to the weight gain. The 4 stroke would be better for extended trolling (no oil in the gas to foul the plugs), they are quieter as I have heard a 60hp 4 stroke idling by and chatted with the owner, did not have to raise our voices at all. Have no opinion on who makes a better motor in the size your looking at.

 

[scoobeb]

Ok would it be worth upgrading to a 20hp 4stroke instead of the 15hp 4stroke or should i just stay with the 2stroke?

 

[LOWEBIGJON]

I would keep the 2 stroke..

 

[Specknreds]

I upgraded to a 4 stroke 25hp Yamaha in '03 from a 2 stroke 25 Yamaha. Very little difference in performance. I lost 1MPH GPS. I did have a few issues with weight but the have made a lot of improvements since '03. I went from about ~35 miles on 6 gallons to way over 60 miles.

I have some serious hours on this little motor with no problems due to the motor. I did have some Ethanol issues before I knew the effects of Ethanol. It's normal for us to 20 miles one way through the marsh on a normal trip.

The oil changes are around $15 using Yamaha parts. Cheaper if you go aftermarket. I stick to Yamaha parts because they are reasonable on small HP. I also have a 200 HP 4 stroke on my bay boat. It will knock a hole in a 100 dollar bill to change the oil and fuel filters in it using Yamaha parts. I use Castol in it and Sierra filters. I'm avaerage 250 to 200 hours a year on it. This is what the guides and commercial boats use and most have over 2000 hours on their 4 strokes.

I get 3.5 MPG in the bay boat running wide open and have seen it get well over 4 MPG just cruising. A buddy with the same boat only gets ~2.5 MPG with his 2 stroke and spends several $100 on 2 stroke oil every few months. You have to remember these boats see more hours in a week than most see in a year.

I will NEVER own another 2 stroke.

 

[moloch16]

My understanding is 2-strokes develop more power than 4-stroke, and Yamaha is a really, really great motor. I'd keep the 2-stroke. (I recently bought a brand new motor and went with a 2-stroke 25HP yammy).

 

[scoobeb]

Yes yamaha is one of the best outboards out there.Most of the name brands are all just as good anymore though.I just think the 20hp 4stroke would do wonders replacing my 15hp 2stroke.I am going to think about it some more before i make a big mistake.The weight is the big issue i'm thinking about.

I have seen tons of videos on the 20hp 4stroke mec/tohatsu and that motor screams with a ton of power for a 4stroke.It has some great hole shot also from what i could see on the videos.I just want a cleaner,better on gas and the environment outboard.

 

[scoobeb]

If anyone has anything they could or want to add to this thread by all means please do so.I mean i'm not sure whats going to happen here in the near future with 2strokes also.The u.s may just ban them to use for good who knows what this country will do anymore.That is another thing that makes me nervous,how long will we be able to use carbed premix 2strokes?I'm sure it won't be here asap but i think some time soon they will ban the use of them and then they are a nice boat anchor.

I personally think if i'm going to replace the 15 i need to get the 20hp for that extra punch.From what i know the merc/tohatsu is no dog,they are strong motors from what i have seen.I was hoping some people in here could tell me how there 15 or 20hp 4strokes perform on their jon boats if anyone has them.That would help a great deal for me to have some peace of mind in making my decision. [-o< .I know the top end would be ok,i don't need a speed demon anyway as i'm only n a jon boat.I think i could do at least 20 to 25mph which is plenty fast for a tiller motor.

From what i have seen i'm leaning towards the merc/tohatsu so far if i do this.I like the ratchet tilt that is built into the merc.All you have to do is pull back on the motor and no need to constantly move a pin up and down.That is a huge feature on a heavy outboard.I don't know if the tohatsu is the same.I need to find that out.

 

[benjineer]

Keep the 2-stroke if you like it unless someone wants to pay you what you bought it for. If you want to help the environment, you've got to sell yours to someone who will use it less than you do, or you could just send it to the scrap yard. Holeshot seems a non-issue when talking about a flat bottom tin. How low does your boat sit when not on plane? It's not quite the same as a heavy glass boat that has to literally get out of the "hole". I think you would like the 20 or 25hp better. I'm running a 25 on a 16ft boat. It planes fast and runs about 24mph, and I'm satisfied. I don't expect them to ever ban 2-stroke pre-mix engines any more than they will ban classic gas-guzzling cars from being driven. I do expect them to raise emission standards on new motors until there are no more premix 2-strokes made. If I had unlimited money to buy new motors for either of my old boats it would be Etec or 4-stroke Yamaha. Both are quiet and fuel-efficient. I'd probably go with Etec because of the hp/wt ratio and no oil changes.

 

[scoobeb]

I put it on craigslist to test the market,i can actually get more then i paid for it but i will take what i paid.I guess if there is no planing issues with a jon boat then maybe it might be worth the gamble.I can sell my motor for anywhere between $2200 and $2500 easily because of how rare they are.My motor is 100%brand new never been used ever since out of the box.

Then i can turn around and get a brand new 20hp tohatsu for around $2400 out of the box,manual of course which is what i want.On the other hand i can get a brand new 20hp 4stroke merc which is the motor i want for close to $2500 give or take a few bucks.I eally like the ratchet tilt on the merc,it would make a 115lb outboard easy to tilt up and down instead of constantly picking the motor up out of the water and moving the pin up and down.

I'm gonna have to give this some serious thought.Like i said getting my hands on a outboard like this ever again will be impossible so i have to make the right choice.Maybe i will just buy a smaller jon boat (12ft) like i want to anyway and throw the 15hp on it and then just buy a bigger motor for my big jon boat.I have a wide 14ft jon boat now rated for a 25hp.I just think the 15hp is a hair under rated once i get all the weight in the boat.I still know it will plane but not by much as a 25 would make this boat fly.

Thanks for all the posts so far,keep them coming.Good smart people here. :mrgreen:

 

[Pappy]

You mention you want a manual engine. One thing to think about on a manual 4 stroke is the starting of the engine. A four stroke only hits every other stroke and compression is usually quite high. You have to pull that manual starter rope quite a long ways to get a couple of power strokes out of that engine and with high compression it can be a bear when the engine isnt in as good a tune as when brand new. Occasional water in the fuel or some other random issue can render the guy on the dumb end of the rope pretty helpless after cranking for a while. The two stroke will definitely have more power and acceleration, hands down. Something to think about! I have stayed out of this and read the various posts with interest and got a kick out of some of the mild misinformation of one or two of the answers so far.

 

[scoobeb]

Hey pappy i know your a smart fellow but the new 4strokes are extremely easy to pull now.They have a decompression device built into them now,you can pull start it with 2 fingers.My yamaha is also easy to pull.Motors are getting easier and easier to pull for the manuals they are not like the older outboards wher they would rip your arm off.Try pull starting a mid 90's 25hp 2stroke johnson,you talk about hard to pull you need 4hands and alot of elbow grease to pull start one of them.

I have pull started over 10 4strokes from a 2.5 to a 20hp and they are simple to start.I just never got to use any of them.I think the 20hp 4stroke merc is a beast from what i have seen.I think it would move my wide 14ft flatbottom like a missle but i want to be sure before i do anything.I'm going to look into it a ton more before i decide to sell it.I will have no problem selling a new 2stroke if i choose to go the 4stroke route.I would like to keep both but my buget won't allow that.Ok anymore info would be just dandy.

 

[LonLB]

I've never been in a SHO 4stroke, but all other 4 strokes, are just slower. There is no way around it, and in my experience, no debating it.

You may get somewhat similar top end speed, but from idle to top end will be much slower.


And I wouldn't worry about 2 strokes being banned.....Maybe someday, but that will be a LONG ways down the road. If ever. (with the exception of select waters-but that is already true; case in point=electric only lakes)


As for brand, again drawing from my own experience (not what I've heard or read about) the only boat engine I've seen catastrophically fail, was a Yamaha 4 stroke.
Sure I've witnessed other motors fail. But I've also had a 50hp 2 stroke Evinrude apart that still ran OK, but one of the cylinders needed to be sleeved to eliminate the deep scoring....Yet didn't fail entirely.

 

[nomowork]

I changed from a two stroke to a four stroke. I really like the noticeable difference in noise level. I can run the motor and not have to yell to my GF who sits on the front of the boat!

In my case, all the new features on the new motor are great!

 

[DanMC]

It wont be long before all things two stroke (including lawn tools,shavers ) will be baned. Just te be on the safe side of the "future" get youself a four stroke Honda (Honda makes some of the cleanest burning motors period,it doesn't mater if it is a weed wacker,lawmover,shaver or an ouboard ) Honda knows more than a thing or two when comes to engines. Honda afterall is worlds largest engine manufacturer for a reason,and if you are talking four strokes...really nobody knows better four strokes than Honda, that is the reason Honda never made a two (primitive technology ) stroke motor for anything...at least consider a Yammy...but for the love of God... [-o<
Dan

 

[scoobeb]

If i go 4stroke it will be a merc/tohatsu not a yamaha.Yamaha is to over priced.I can get a merc 20hp 4stroke for over $400 less then a yamaha and darn near $1000 cheaper then a honda.If you want to get right down to it the tohatsu is the best outboard hands down for what your getting for the money.I just like the ratchet tilt that merc has and no other outboard has that feature.Honda is way over rated in my opinion.Are they good outboards,of course but the price you pay is insane.All the newer 4stroke outboards are built to last no matter what you buy,i'm talking major brands here also.

The 20hp 4stroke merc/tohatsu has the best power to weight ratio for all the four strokes from what iv'e gathered and from a ton of peoples experiences with their small mercs.I think the merc/tohatsu is the best 20hp 4stroke out there for mainly the features it has.The 20hp 4stroke merc/tohatsu has the best gear ratio(2.15) for the best hole shots,an (awesome ratchet tilt system(merc only) to help out with the weight of the motor for an easy tilt system,all the controls built into the tiller,electric start also has a manual recoil to pull start it unlike the yamaha,plus they are a sharp looking outboard.Built extremely good and built to last forever if taken care of.

 

[jasper60103]

The 20hp 4stroke merc/tohatsu sounds interesting. I wonder if it would provide decent performance for my tinnie? i.e. Plane easily with two adults, gear and maybe reach 20-25mph? It's 16' long, semi-v, around 400# and I weigh about 200#. I like to remove my motor and store over the winter, and the 25hp or larger 4 strokes weigh too much.

 

[LonLB]

I know this isn't what you asked jasper, but if I were you I'd forget about it. You just can't beat that motor you have on a boat your size. Those things are light, and ROCK SOLID reliable. In my experience. If I had a boat that size, that is the motor I would put on it.