2 stroke vs 4 stroke?

mako12 · Posted: Sat Jun 23, 2012 9:04 pm Post subject: 2 stroke vs 4 stroke?

In the process of looking at a boat to buy. What are the main differences between 2-stroke and 4-stroke, both 60hp?

crocodile · Posted: Sat Jun 23, 2012 9:34 pm Post subject:

Hello mako12,

I recently had cause to replace my 60hp 2 stroke Yamaha.
For various reasons the choice came down to either a 60hp Yamaha 2s or 4s.
I did get to drive another boat with a 4s so I believe that it is a fair comparison based on actual experience.
Two stroke
pros
about $1000 dollars cheaper
much better acceleration
cruises at very lazy 4000 rpm
cons
noisier at idle
rougher at idle
uses a little bit more fuel at cruise(refer to Yamaha performance bulletins)
some two stroke smell when cold started

Four stroke
pros
uses a little bit less fuel
quieter at idle
a little bit quieter at cruise, not much (tested by ear, not scientific)
smoother at idle and up to 2000 rpm
cons
comparatively sluggish acceleration
about $1000 dearer
higher rpm needed for same performance

I don't do high hours, freshwater, lots of trolling, really long trips.
I do cross bars and often carry a load.
My boat is a Webster Twinfisher cat with a single engine that spins in the tunnel.
The two stroke has the big, slow turning 13" diameter prop whereas the four stroke standard has a much smaller prop, the high-thrust four stroke was much dearer and heavier.
I theorise that the bigger prop assists performance in the catamaran application. Other owners with smaller props report some ventilation.
Mine never ventilates unless grossly over-trimmed.

I bought another two stroke.

Joey_1987 · Posted: Sat Jun 23, 2012 10:37 pm Post subject:

Ditto what has already been said. Also the Mercury 60hp 2 stroke (made in USA) is a fantastic engine and at cruise it posts figures that need to be seen to be believed. Of course a 4 stroke will be quieter, no exhaust smell, less vibration (only really applies at idle/lower RPM's) but for some things a humble 2 stroke can be the way to go. This is a review that springs to mind when comparing 60's, check the numbers against others and go with what you like: http://boatpoint.com.au/engine-reviews/2004/mercury/mercury-60-8304.
Cheers.

mako12 · Posted: Sat Jun 23, 2012 10:51 pm Post subject:

Is the sound THAT much different?

Was at a boat yard today and the sales person reckons they can't sell a Haines Hunter with a 200 ETEC on it because its a 2 stroke engine. He also said that a 4 stroke will mean the resale value of the boat will be higher.

mako12 · Posted: Sat Jun 23, 2012 11:17 pm Post subject:

What about things like service fees, oil changes etc.? I read somewhere that 4 strokes cost more to be serviced?

theantspants · Posted: Sun Jun 24, 2012 8:00 am Post subject:

In my opinion I made the right decision to go with a fourstroke
I save on fuel every trip, I can have a conversation with everyone
on the boat. If I lose my job tomorrow I can afford to fish.
I dont need super fast hole shot, I do travel long distances to fish.
I just put in petrol and I am away. no mixing or worrying about the
engine mixing. No fumes. 13yrs on my yam 4 stroke and still happy
I service once a year. average about $450 a go but last one cost me $750
but my motor is 13 years on and I got all the carbies redone
last 3 trips out I have used a lot less fuel after having the work done
so I will recoup that (saved 15 litres each trip from same trip as pre service)

But as stated by others its horses for courses
work out what YOU need in a motor
We can only tell you what we needed in a motor
all motors these days are pretty good.
13 years ago 2 stroke to 4 stroke was a big difference
with most manufacturers now offering direct injection 2 strokes
it may not be worth the extra bucks for a four if you dont use your
boat often enough
Cheers Ant
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Freakish · Posted: Sun Jun 24, 2012 8:29 am Post subject:

Big consideration is weight difference. You want/use livey tank/dual batts/fuel down back ? How many u intend aboard ? Problem largely disappearing now due to the 60/70 class getting MUCH lighter in 4 stks...not long ago was a bit of an issue when guys just assumed coz a 60hp 4stk was within hp rating they could just bolt it on...could weigh 80-100kg more tho. New suzi/honda 60's are only 105-110kg's maybe which has helped hugely repowering older 2 stk rigs.
If its a new boat tho chances are its made to take a 4stk, just be aware if buying 2nd hand rigs rather than new that might have one of the earlier really heavy type 4stk on an older hull.

TheBream · Posted: Sun Jun 24, 2012 8:53 am Post subject:

i have both right now and it was money that made me have the 2smoke

get a 2smoke and alwasy wish you had the 4stroke or go 4stroke and then you will never go back to a 2smoke

i am bias and i do really like the 4strokes but alot of the more moden 2strokes are just as good
only type to stay away from is the old tech cheaper carbie 2strokes
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frozenpod · Posted: Sun Jun 24, 2012 8:58 am Post subject: Re:

TheBream · Posted: Sun Jun 24, 2012 9:20 am Post subject:

and here i was thinking that horsepower ratings were the same so a 115horsepower 4stroke had the same power as a 115hoursepower 2stroke the only diffrence is the weight or power to weight ratio

not too sure about others on here but 50hrs a year is pretty low i would think most would be around 100hrs a year