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Yamaha 150 4 stroke vs 2 stroke

dtemp1

New member
I am considering buying a new

I am considering buying a new 06 model 150 4 stroke for a 19' Polarcraft deckboat. I'm used to 2 strokes. I've always heard 4 strokes have less torque. How will they compare? will I be disappointed in the 4 stroke? any advice will be greatly appreciated.
 
"David, you have heard correct

"David, you have heard correctly. In almost any comparison you can make the two stroke will outperform the 4 stroke.

With the two stroke, 150 in this case, every 360 degrees of crank rotation is driven by six power strokes - all 6 cylinders have power every rotation. It's 4 stroke cousin will only have 3 fire per rotation because the other 3 are exhausting.

Given that the motors are nearly identical on displacement you can do the math. That's why the 2 stroke will get out of the hole, up on plane significantly quicker than the 4.

Additionally, despite all the hype about how much more fuel efficient the 4's are, the actual test numbers from "real on water tests" do not exactly pan out.

Yamaha is definately better in that catagory than all the rest, but for the most part test results have shown the 4's to be less than 10% more efficient in the "majority" of cases. And yes I have the numbers - recently posted quite a few on the OMC section of this board.

Once you add in all the "extra" maintenance required by a 4 stroke, the actual operating costs tend to leave the 4's more expensive to run.

And yes, the 4's are quieter. But again, not to the degree they are "hyped". A 2 stroke at 3/4 throttle produces the same DB reading in the cockpit as a 4 at WOT - so not really the earbleeder the salesman would have you believe.

I am not saying to stay away from 4's, but don't go in blind. They need to be diligently maintained - think of the schedule in the owners manual as the absolute minimum (I recommend twice the interval for oil/filter changes, valve adjustments, belt adjustments etc).

A 4 stroke doesn't like to sit around for months on end and then only be run for a few hours on a weekend. But if you are willing to care for it, it may well last a good few years.

Unfortunately, they have not been on the market long enough to really get a good sense of their lifespan. We know you can have a 30 or even 40 year old 2 stroke still working fine, it's far more difficult to find a 4 stroke out there that's even 10 years old - so tough to form an opinion.

If you think you will be happier with "2 stroke" performance, you always have the option of the Direct Injected 2 stroke motors. In most cases their initial cost is slightly lower than a new 4 stroke, they are just as environmentally clean, fuel efficient, quiet etc etc and will kick the snot out of their 4 stroke counterparts - just like their older cousins...."
 
Thanks Graham for the advice.

Thanks Graham for the advice. I guess you confirmed everything I've heard before. I suppose thats why after some makers went the 4 stroke route they came back and added a 2 stroke back to their line .
 
"Don't get me wrong, I&#39

"Don't get me wrong, I'm not totally against a 4 stroke. But I really do believe that the marine industry as a whole has done a grave dis-service by not informing customers about the additional maintenance and care that MUST be done to them.

And as you note, Merc, BRP/OMC, Yami and Tohatsu all produce Direct Injected 2 strokes. In fact, the only Evinrude's on the market are DFI Etec's.

While they are hi-tech motors that only vaguely resemble a classic 2 stroke, they did however, not only maintain, but improved on 2 stroke performance.

I personally believe that as time moves along you will see the DFI market become the "big market" with a smaller variety of 4 stroke choices being offered (in the higher horsepowers) as more of the boating public comes to learn that 4's are the far more expensive option in the long run.

At present, in the 150 horse class, I really can't figure why anyone would hang anything other than a 150 Merc Optimax off the back of a outboard powered boat if they were considering a brand new engine.

And that's not just because I'm a Merc guy (I run a 140 horse OMC V4 looper - but don't tell my Merc buddies)
, but their injection system is (in my opinion) far superior to the others out there..."
 
Who eliminated 2 strokes then

Who eliminated 2 strokes then brought them back? 2 strokes are on a quick decline in sales world wide..less than 6% of all new outboard sales are 2 stroke. Hate to think how much 2 stroke oil will cost once the demand for it is so low it becomes almost a special order item. 2 stroke oil would also be an easy target for high taxation in the future to force them off the market.
 
"Rollie, we were talking about

"Rollie, we were talking about the direct injected models, not the (classic) 2 stroke."
 
"Graham, I'm not a fan of

"Graham, I'm not a fan of efi 2 strokes. I've seen way to many of those on the mechanics bench too. For all the downsides of a 4 stroke..that crankcase full of oil prevents some of the problems seen in all 2 strokes (post pre-mix) I still use a carbed 2 stroke which has great power to weight ratio but I'm on my 3rd powerhead going into season #12. The guys who have paid large and jumped to the 4 strokes aren't experiencing the same kind of powerhead failures. I'll run this carbed 2 stroke until it dies one more time. Being carbed I can work on it myself when small problems do arrise. When it caves the next time I will be biting the bullet and joining the 4 stroke crowd. David, one very good upside to a larger 4 stroke is how well they troll if you need them to. Smooth, steady rpms, quiet (how many times have I heard guys engage a starter motor on a 4 stroke that was already running because they couldn't hear it) The guides here love them on rougher or big tide flow days when the kickers would be cranked up to full throttle to maintain a proper trolling speed. They just flash up the main and carry on."
 
"Rollie, I'm fairly certai

"Rollie, I'm fairly certain our experiences with regards to how common motor failures occur are somewhat different.

You live in an area where it's probably a fair guess that most outboards see hundreds if not thousands of hours use in a season. In BC motors tend to blow due to extensive use - they reach their lifespan - out here, and in much of the country, motors die from under-use coupled with lack of proper maintenance and storage practices.

Where I run, 50 hours of use in a season is LOTS for the average motor.

While I don't doubt that a well used, regularly maintained 4 stroke is durable, for most boaters away from the coasts, that's just not the case.

You wouldn't park your car for 6 or more months on end, then without so much as an oil change, take it out on the highway and put the pedal to the mat for 3 or 4 hours, then return it to the driveway for another few weeks before taking it out again - then do that year after year and expect it to last. Yet that is exactly how outboards are treated in most of the country.

Where I am it's not uncommon to find a 10 year old motor, with less than 200 hours of run time, that has never seen a new part since the day it came off the assembly line.

That's why I believe that a 4 stroke will be a severe disappointment over the longer run to most "recreational boaters". They just won't put the money in to properly care for them, because they just don't use them enough and won't spend money on something they are not using.

Yet, they will expect them to keep going the way old 2 strokes did, which could be neglected and abused and would still fire up every spring...

So for the areas where I boat, and the people that use boats "occassionally" I will still recommend that they look at Optimax, Etec, HPDI or DFI Tohatsu's.

Yes, things can still go wrong, but they will take alot more neglect, so in 20 years they can still be running (as they are hitting the 300-400 hour mark), long after their neighbours 4 stroke has been scrapped because it "costs too much to fix" from all the neglect it had suffered..."
 
"Graham, I average about 175 t

"Graham, I average about 175 to 200 hrs per season on my main. I've averaged about 900 hrs on all the powerheads before I loose a cylinder due to catching a ring, water getting into a hole etc. Most of hours hours here go on the kicker engines...I'll put as little as a 1/2 hr on the main in a day and 9 1/2 hrs on the kicker. My boat is layed up on the trailer except for the odd winter outing from late Oct to mid April. I do fire it up every 2 weeks on the hose. I don't understand putting out 20K for an engine and then not doing basic maintenance to protect your investment. Most of which anyone could do themselves even if they paid a mechanic the first time and hung around and watched so they could do it from there on. Just like guys who hire me and are mom about the fact they own a boat and are only hiring me to see some techiques to speed up their learning curve on catching kings/chinook."
 
"Rollie, absolutely agree with

"Rollie, absolutely agree with you. And that's why guys like us are on this board. We take the screwdriver to the motor and keep her tuned properly.

But we really are a minority. This is a "disposable" world now. And the uninformed will believe all the hype that high priced marketers can throw at them.

And your stated yearly average of 175-200 is the equavalent of about 10 years running where I am. The motors I see would have to survive 80 to 100 years before they ever saw 900 hours.

That's where I think the marine industry has failed the "recreational boater". You get all kinds of data and stats that are pertinent to the commerical or professional boater - those that DO regularly service and repair their motors. That know how to treat them etc etc.

The average Joe just wants it to fire up on the 4 long weekends that he isn't doing overtime and haul the kids around on their tube for that week of holidays at the lake.

And selling him a 4 stroke without impressing that it MUST be taken care of more diligently than grand-dad's old 40 horse Gale, while very good in making a quick sale for the dealer, is doing a grave dis-service to the entire industry.

I've never seen a 10 year old 4 stroke, why? partly because they are still fairly "new" to the market, but partly because they are all scrap now as well - deemed too expensive to fix. Why spend 5K repairing it when you can have a brand new one for 12?

No wonder. That motor was run for 5 years without a bit of prep or maintenance (what do you mean I need to service it 3 times a year at 100 bucks an hour plus parts - dad never brought his motor in and it worked just fine....)"
 
"I have owned over 30 2 smoke

"I have owned over 30 2 smoke johnrudes and maby 5 mercs in my life, and if you put all the problems I had with all those motors together, they wouldnt ammount to all the problems ive had with just 1 4 stroke 115 yamaha, and some of those 30 I had were crap when I got them, these 4 storkes are not made two be on the water they are car motors, maby in about 20yrs they will get it right, but until then you better learn how to work on it yourself, eather that or marry a really rich old lady thats loose with her money, and if they want a great lightweight 4 stroke that will work on a boat why havent they put out a rotory outboard yet, think about it no pistons, valves, pushrods, ect just 1 moving part and the motor can tac 20 grand, think of the holeshot you could get with a rig like that"
 
"Amen brother! If you're g

"Amen brother! If you're going to have an outboard motor then you better take a "mechanical interest" in it, just like with a motorcycle or any other machine other than a car that you "just get in it and drive". I've had 2 strokes in a 3,4,40,90 and 115HP with almost no problems, but I do enjoy the mechanical/maintenance aspect of ownership and it's really nice to take off for a 50 or 100 mile run down the river and feel pretty darn confident that your motor is not going to quit, especially with wife and family onboard. Maybe Mazda should think about that rotary outboard engine...HP to weight ratio could be great!"
 
"OMC had a rotary along time a

"OMC had a rotary along time ago now but it was a lemon, interesting OMC produced a rotary race engine that generated massive hp and with 122 cu it produced 330hp at one race the Galvoston speed classic they placed 1st, 2nd, and third lapping the entire field three times.The APBA banned them from racing because it was too embarassing for the other competitors and manufacturers."
 
"Personally, I think 2 strokes

"Personally, I think 2 strokes are better for the long term. The oil in the petrol just keeps the motor lubed internally when not in use. 4 stroke valves sometimes get stuck open if left for ages - especially on small motors with weaker valve springs. I am rebuilding a 1970 Johnson at present. I pulled it apart and it is in excellent condition. No corrosion what so ever. With a crank rebild and rebore, it'll be almost as good as new. In fact, might even be better than a new one in 1970."
 
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