2 stroke vs. 4 stroke

[raypoza]

I've recently purchased a sky boat, and I need to choose a motor, is the higher price of the four stroke justifiable?

 

[rodbolt]

Re: 2 stroke vs. 4 stroke

depends<br /> what are you trying to do with the sky boat?<br /> how is the fuel quality and the training of the local techs?

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi,<br />Can You tell us what a "sky boat" is? (Make and model)<br /><br />A 4-stroke is not necessarily more expensive than 2-strokes. Many new 2-strokes with Direct Fuel Injection (DFI) are also expensive. Evinrude E-tech, Tohatsu TLDI, Mercury Optimax, Yamaha HPDI for example.<br /><br />Since I do not know what type of boat You have (seize, weight, planing boat or not etc) it is very difficult to give any advice.<br /><br />If You plan to do much maintenance Yourself it is probably wise to select a 2-stroke with carburators.<br />If You plan to let a marine service center do most of the maintenance make sure it has a good reputation and in vicinity where You live. It wil be easier if any trouble, warranty and the service itself if You do not need to travel so long to have things fixed.<br /><br />I had 2-stroke before and I have a 4-stroke today. It was about 10 year between the two outboards and although 2-stroke technology has advanced since then I just like the 4-stroke very much (Electronic Fuel Injection - EFI, instant start, very quiet, fuel efficient, silent, no smoke and gas smell). Older 2-strokes just can not achieve all this. Newer 2-trokes can but then it will be almost as expensive as a 4-stroke. <br />I use a Yamaha F115 4-stroke (2003) and I like it alot. It has been on the market since 1999 and obviously has no problem anymore with such things that can be problem at introduction of a new model. In 2004 it became CARB 3-star rated (was 2-star before). It is one of the most proven 4-strokes in this seize together with Honda BF115 4-stroke that probably has been longer on the market.<br />If You are in the market for a 115 hp outboard and You have the money a Yamaha F115 is a good choice. Other makes produce also fine outboards like Mercury, Honda, Suzuki, Johnson etc. I'm just happy with my F115, that's all.<br /><br />Good luck!

 

[raypoza]

Re: 2 stroke vs. 4 stroke

Hi, Thanks for the replies, I realize that It's not an easy question.<br />The boat is an "Aquascape" a South African design, with a proposed mariner 125hp 2-stroke or a mariner 115hp - 4 stroke.<br />The boat is an all rounder, good for watersports as well as to go out to sea.<br />I'm very new to boating, and my knowledge is quite limited.

 

[raypoza]

Re: 2 stroke vs. 4 stroke

size is a 18ft

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi,<br />OK, 18 ft planing boat then.<br />I happen to own a 19 ft bowrider myself so I'm rather familiar with this seize boat.<br />A 115 hp 4-stroke will for sure be enough. A 125 hp 2-stroke also of course.<br /><br />The Mariner 125 hp 2-stroke is a carburated outboard. It is "old proven technology". It has nothing of the new 2-stroke technology You find in Mercury/Mariner Optimax for example (No Direct Fuel Injection for example). It will be thirsty on fuel and it will smoke and smell gas when running (in tailwind the gas smell can start to be rather irritating on older 2-strokes - belive me!)<br /><br />The specification for Mariner 125 hp 2-stroke:<br /> http://www.mercurymarine.com/mariner_125 <br /><br />As I wrote before It is probably the right choice to select a 2-stroke carburated model like this If You plan to do the most maintenance Yourself. If not and You have the extra money I advice to select the Mariner 115 EFI instead. You will get more advantages:<br />- instant start (because Electronic Fuel Injection, like in all modern cars).<br />- low fuel consumption (at least 30% lower than comparable 2-stroke with carburators because in a carburated 2-stroke 30% of the fuel just pass trough the engine and go into the sea unburned).<br />- more environmental friendly because above and it is 3-star rated and have low emmissions that the Mariner 125 does not come close to.<br />- more silent (you probably want to make some sort of conversation with the other people in the boat, even at higher rpm), old technology 2-strokes tend to be rather noisy.<br />- better in low rpm use (for fishing, trolling).<br /><br />The negative thing with a Mariner 115 EFI 4-stroke will be it cost more, You are more in the hands of marine mechanics because a 4-stroke is somewhat more mechanical complicated and has more electronics than old technology 2-strokes.<br /><br />The Mercury 115 EFI and Mariner 115 EFI is exactly the same outboards, so that is a plus regarding places where You can have it serviced (at least after warranty has expired).<br /><br />Specifications Mariner 115 EFI:<br /> http://www.mercurymarine.com/mariner_115_efi_fourstroke <br /><br />What price difference is it between the Mariner 125 hp 2-stroke and the 115 EFI 4-stroke?<br /><br />If You for some reasons prefer 2-strokes and want latest technology have a look at a Mariner/Mercury 115 Optimax then. It is almost identical in performance, fuel consumption, weight, cost (a little cheaper), 3-star rated, as a Mariner/Mercury 115 EFI.<br /> http://www.mercurymarine.com/mariner_115_optimax2 <br /> http://www.mercurymarine.com/mercury_115_optimax

 

[raypoza]

Re: 2 stroke vs. 4 stroke

Hi, Many thank for the reply, I only realized now, I meant Ski-boat!

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi,<br />I use my bowrider with Yamaha F115 4-stroke for various things and one of them is for water ski and wakeboard. When wakeboarding I use a Big Air universal pylon. <br /> http://www.bigairpylons.com/ <br /><br />Here is a picture of my boat:<br />

<br /><br />Happy boating!<br />/Bo

 

[TOHATSU GURU]

Re: 2 stroke vs. 4 stroke

For sking you would like the 2-stroke outboards performance better than the 4-stroke. Much better holeshot for the same horsepower. But, unless you get a Direct-Injected 2-stroke the 4-stroke will have better fuel economy and be quieter.

 

[raypoza]

Re: 2 stroke vs. 4 stroke

Hi Bo,<br /><br />Once again many thanks for your advise, I have just placed an order for the 135hp optimax.

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi again,<br />The Optimax 135 hp 2-stroke wil be very good choice. 3-star rated, Direct Fuel Injection (DFI), V6 (6 cyl) etc. That will give a good force for water skiing etc. <br />/Bo

 

[rodbolt]

Re: 2 stroke vs. 4 stroke

keep us posted on the opti-pop. I am interested to see if they work there any better than here .

 

[lawyertob]

Re: 2 stroke vs. 4 stroke

Bo,<br /><br /> Just out of curiousity what does CARB rated mean? And where do you find the ratings? I tried an Internet search and came up with nothing.<br /><br />$0.01 for your thoughts,<br />Joe

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi Joe Glastron T186,<br /><br />CARB is short for California Air Resources Board.<br />It has become the "standard" for emission levels all newer outboard (and inboard) consumer engines follows. The marine manufacturer glue a sticker with 1, 2, 3 (or 4, but I do not think any manufacturer has 4 yet) star rating on the engine so it is easily seen what emission standard the engine meet, and if a consumer want to to contribute to a cleaner environment he/she can choose an engine with higher rating (more stars).<br /><br />To the best of my knowledge almost all new EFI (Electronic Fuel Injection) and DFI (Direct Fuel Injection) that has been made after 2003 is at least 2-star rated, more often 3-star. Before that (or so) I belive 2-star was the highest standard. And if You buy a new outboard today that is not carburated 2-stroke it is in most cases 3-star rated. I do not think there is 4-star rating yet for outboards (for inboards it is possible according to the document below).<br /><br />I have a Yamaha F115 4-stroke 2003 myself that is 2-star rated, it became 3-star rated for 2004 season.<br /><br />To the best of my knowledge any carburated 2-stroke outboard can never meet the CARB standards because for example as much as 30% unburned fuel just pass trough such engine and into the sea water. So that is why it is advisable to select a 4-stroke (carbed or EFI) or 2-stroke DFI when buying a new outboard today to get most of the fuel burned in the engine. Better for the environment (but more expensive to buy such outboard).<br /><br /> http://www.arb.ca.gov/homepage.htm <br /><br /> http://www.arb.ca.gov/msprog/marine/marinectp/marinectp.htm <br /><br /><br />Manufacturers Advisory Correspondence:<br /><br />MAC 03-01 (added February 4, 2003)<br />Hang Tag and Star Labels for 2003 and Later Model Year Spark-Ignition Marine Engines <br />(Word97 - 71K) or (Acrobat - 133K) <br /><br />The following is copied from above Word/PDF document:<br /><br /><br />One Star – Low Emission<br />The one-star label identifies Personal Watercraft, Outboard, Sterndrive and Inboard engines that meet the Air Resources Board’s Personal Watercraft and Outboard marine engine 2001 exhaust emission standards. Engines meeting these standards have 75% lower emissions than conventional carbureted two-stroke engines. These engines are equivalent to the U.S. EPA's 2006 standards for marine engines.<br /><br /><facsimile of the two-star label><br /><br />Two Stars – Very Low Emission<br />The two-star label identifies Personal Watercraft, Outboard, Sterndrive and Inboard engines that meet the Air Resources Board’s Personal Watercraft and Outboard marine engine 2004 exhaust emission standards. Engines meeting these standards have 20% lower emissions than One Star – Low-Emission engines.<br /><br /><facsimile of the three-star label><br /><br />Three Stars – Ultra Low Emission<br />The three-star label identifies engines that meet the Air Resources Board’s Personal Watercraft and Outboard marine engine 2008 exhaust emission standards or the Sterndrive and Inboard marine engine 2003 exhaust emission standards. Engines meeting these standards have 65% lower emissions than One Star – Low Emission engines.<br /><br /><facsimile of the four-star label><br /><br />Four Stars – Super Ultra Low Emission<br />The four-star label identifies engines that meet the Air Resources Board’s Sterndrive and Inboard marine engine 2009 exhaust emission standards. Personal Watercraft and Outboard marine engines may also comply with these standards. Engines meeting these standards have 90% lower emissions than One Star – Low Emission engines.<br /><br />Hope it helps.<br />/Bo

 

[swist]

Re: 2 stroke vs. 4 stroke

One negative I've heard on Optimax is they are very loud.

 

[lawyertob]

Re: 2 stroke vs. 4 stroke

Originally posted by Bo:<br /> Hi Joe Glastron T186,<br /><br />CARB is short for California Air Resources Board.<br /><br />/Bo

Thanks Bo,<br /><br />That is something interesting to look at if/when I buy a new motor. My current 1975 Johnson 115 would probably be about a negative 5 or so on the CARB scale.<br /><br />Thanks again,<br />Joe

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi swist,<br />You wrote:<br />"One negative I've heard on Optimax is they are very loud."<br /><br />As for Mercury 115 EFI and Mercury Optimax 115 they are almost identical in noise level at all RPM.<br />I have read a test in a Swedish boat magazine and I'm sure they had almost the same dB levels. I can have a look in the magazine if You are interested to see the numbers (they measured with a dB meter) in two indentical boats, one with the 4-stroke and the other boat had the 2-stroke.<br /><br />/Bo

 

[bossee]

Re: 2 stroke vs. 4 stroke

Hi,<br />Found the magazine, dB comparison:<br /><br />Mercury 115 Optimax<br />Max RPM (5600 in test): 85 dB<br />Minus 500 rpm: 82<br />Minus 1000 rpm: 81<br />Minus 1500 rpm: 80<br />Minus 2000 rpm: 77<br /><br />Mercury F115 EFI<br />Max RPM (5400 in test): 85 dB<br />Minus 500 rpm: 82<br />Minus 1000 rpm: 80<br />Minus 1500 rpm: 78<br />Minus 2000 rpm: 75<br /><br />/Bo

 

[Mercathode]

Re: 2 stroke vs. 4 stroke

135 was a great choice!