4-stroke versus 2-stoke

[Sturmey Archer]

Hi all,

I am sure this topic has been covered many times before but I am new to this game.

This morning I went to see a new Avon 620, I am having trouble on deciding on an engine. The dealer suggests a Mercury 115 Optimax, but I had my heart set on a Honda 4-stoke. I have decided -I think- to go with Mercury but don't know if 2-stoke or 4-stoke is the way to go.

Speed is not a priority. Reliability is my no. 1 objective, followed by noise (lack of!) and fuel consumption.

Any pointers would be appreciated.

[Richard B]

"Reliability is my no. 1 objective, followed by noise (lack of!) and fuel consumption."

Reliability - all modern engines should be good!
Noise (lack of) - probably four stroke.
Fuel consumption - again all modern engines good!

Do a search as there's loads and loads, and loads on this subject

Suzuki 140 4-strokes are a much more popular choice on your size of RIB. From owners' reports, I believe you would find it outperforming a Honda 130 on every count.

HTH!

[ADS]

Originally Posted by Sturmey Archer

Hi all,

I am sure this topic has been covered many times before but I am new to this game.

This morning I went to see a new Avon 620, I am having trouble on deciding on an engine. The dealer suggests a Mercury 115 Optimax, but I had my heart set on a Honda 4-stoke. I have decided -I think- to go with Mercury but don't know if 2-stoke or 4-stoke is the way to go.

Speed is not a priority. Reliability is my no. 1 objective, followed by noise (lack of!) and fuel consumption.

Any pointers would be appreciated.

Optis are not known for being quiet although this is not always a bad thing!
If quietness is high on your list I would think a Suzuki or Yamaha 4-stroke would be best suited to you. The Yamahas are expensive so my choice would be a Suzuki DF115/DF140.

regards
Alex

EDIT: Richard has just edited his post now and mentioned the Suzy, it would be my choice. PM Nautiboy he had a avon 620 and suzy 140.

[Phil Davies]

Originally Posted by Richard B

Suzuki 140 4-strokes are a much more popular choice on your size of RIB. From owners' reports, I believe you would find it outperforming a Honda 130 on every count.

What da man said

[Hugh Jardon]

Originally Posted by Sturmey Archer

Hi all,

I am sure this topic has been covered many times before but I am new to this game.

This morning I went to see a new Avon 620, I am having trouble on deciding on an engine. The dealer suggests a Mercury 115 Optimax, but I had my heart set on a Honda 4-stoke. I have decided -I think- to go with Mercury but don't know if 2-stoke or 4-stoke is the way to go.

Speed is not a priority. Reliability is my no. 1 objective, followed by noise (lack of!) and fuel consumption.

Any pointers would be appreciated.

i have done a lot of research in this area and some pros an cons are to be considered

if you want quiet, economy and reliability then go 4 stroke

if you want speed and economy go opti or hpdi

i think 4 strokes are the best all round for economy and probably reliability

honda do a nice vtec 150 and suz do a df 140

pros and cons of each

vtec, 5 yrs warranty, reliability, a bit heavier than 140, maybe more expensive

suz, lighter than honda, may only be 127hp, has a lower spec low end from a smaller engine, reliabiliity and economy, poss cheaper than honda

i was considering a 620 and did much looking and reading and everything and was going to go for a honda 150, but i have a honda 90 on another boat and it has been fab.

lots of people will give you views on this

here is a report i found useful on the 150s, note suz not there but lots of people rate them, lots of personal preference comes in here


http://www.yamaha-motor.nl/products/...ws/article.jsp

i contacted every single avon dealer in the country in the last two weeks and got pricing from them and i can tell you where the best deal is to be had on one of these boats

cheers

chris

[Brightside]

I recently had same question. I went for the Yamaha F100.. No regrets, its is quieter than any engine of similar size I have seen or heard... Too early to tell about ecconomy or reliability.

The question I had about the Honda 4 stroke was the weight, a great deal higher than suzuki or yamaha.

[rbw156]

Thanks, Chris, for the link to the fantastic article.

I've just been through a similar buying process and purchased a Mercury 150 Opti. I'm thrilled to bits with it! The torque is awesome.

Two strokes do tend to be noisier, however, I'd balance this by saying that it is very useful to be able to hear the engine RPM change. It helps get in tune with the RIB whilst driving.

I think that reliabilty and fuel consumption between 2 and 4 strokes on all modern engines is comparable, ie it is not a factor on which to differentiate engines.

You can shop around to get a good price, however, make sure that you are making a like for like comparison.

Don't be mislead by the quoted weight of an outboard, what is relevant is the installed weight, ie including prop, controls, instruments, oil, etc.

You might also like to consider that many manufacturers use the same engine block for a range of powers, ie one block can be used for a 90hp, 115hp and 150hp. If you go for the 90, then you have the worst power to weight ratio, but you also have the least stressed engine! On the otherhand, if you go for the 150, then you have the best power to weight ratio, but the most stressed engine. I believe that the Mercury 150 Opti block is also used in the 135 and 175.

The Mariner 150 is around £300 - £500 cheaper to buy than the Mercury 150.

I'd also recommend that you go for a leading edge technology (3-5 years), not bleeding edge (1-2 years)! Often market pressures encourage manufacturers to push their products onto the market before all the little niggles have been resolved.

Good luck.

[Hugh Jardon]

Originally Posted by Chris Hartley

i contacted every single avon dealer in the country in the last two weeks and got pricing from them and i can tell you where the best deal is to be had on one of these boats

cheers

chris

but have decided not to buy an avon 620 for following reasons, please note these are personal reasons and not in anyway to slight the boat that others enjoy.....

bit too small for my needs, when they are set out with all the bits i wanted you have to squeeze around the boat, past the helm, past seats etc, imagine if it was full of people or a few friends on board

talk of a slightly wet ride in the back

maybe not riding the water as well as other boats

engine tilts into boat and not into an area that is closed off so to speak

no chick pit or sunbathing area at front, key consideration for the mrs

not enough room behind drivers seat to stand etc like on other boats

i have decided to go for an older but bigger boat, a picton cobra 7.5 as i feel this meets my needs better and i do like the layout.

one very careful consideration i would give if you get a 620 is where the seats and helm console are fitted on the boat, the reason is that balance of the boat is affected and getting it in the right place for your needs is important but is a gamble on what the resultant handling and balance will be like, so take care, also on second hand ones the layout will be to others spec and the balance might not be there for your needs.

if it helps i am happy to share details of the quotes i got and who seems to have the right balance of price and service and knowledge, just post me a private message and will be happy to share what i have learnt

also on engines, the 150 honda is lighter than the 130 apparently and is newer technology, and much faster etc. personally i dont think you can go wrong with a honda or a suzuki or a merc or a yam of the modern types

i have a yam, a honda and a merc and suzuki bikes!!!

chris

[Ribster Rache]

AVON 620 we think 115 opti a bit on the small side, you will be harder on the throttle than say on 135 opti ,we would go for a 150 opti.

Friends Avon 620 has 135 opti it a good package, another friend has Avon 580 with 90 opti under powered no good.

But if you want to go four stroke and i think you do ,the 140 Susuki would be the bees knees, forget the Honda you would not be disappointed promise !!

[timboli]

I have tried an AVON 620 with a Yamaha 150 4 stroke,top speed was around 43 knots,weight seemed Ok as boat handled well,a quiet engine with Yamaha reliability IMHO.Although you may not be interested in top speed,it does mean you can get more relaxed(and economical) cruising at lower speeds.If you go to the Yamaha website http://www.yamaha-motor.com/outboard...px?ls=outboard you can get cosumptions in US gallons on a variety of boats,when I was looking,I ended up with the idea that I would average 4 galls per hour but never got to try this for real.

[Richard B]

Originally Posted by timboli

I have tried an AVON 620 with a Yamaha 150 4 stroke,top speed was around 43 knots,weight seemed Ok as boat handled well...

Wasn't this the one that nearly threw the passenger in the rear seat overboard? Oh yes, I see, it handled well!

(Louise didn't get that, I assume that you will!)

[Rogue Wave]

I am only 53 so I ain't old enough for a four stroke engine! I should be ready in about 12 years time!

However if you must by a four stroke than Yammies are difficult to beat!

nearly all motors (2 and 4 stroke) nowadays carry serious electronics which may affect reliability if the sensors fail!

I am the worlds no 1 Opti fan but I wouldn't recomend any one to buy the 115 opti (bleeding edge technology) cos they aint right yet!

Everytime I look at the Adeventurer hull I think that I wouldn't want to go fast in that so i think a big lump on one is a waste.


I'd give serious consideration to the Etec range and for out and out reliability I'd go for the yamaha V4 125 2 stroke. 135 Opti might be cool

Power to weight ratio is important on a smallish RIB so the weight of the engine is an important factor as is length of warranty

[Mollers]

All the info given is pretty accurate so far in my view other than 4 strokes are in no way more reliable than two strokes. When they stop they stop. One wont do it any more than the other. The noise thing, anything over 25 knts, all you hear is the wind thundering past your ears . So what does it matter what's hanging off the back. Personally I prefer a two stroke. The power delivery lb for lb is superior. As for fuel? The difference is not worth worrying about with a modern HPDI.

[Hugh Jardon]

Originally Posted by Mollulnan

All the info given is pretty accurate so far in my view other than 4 strokes are in no way more reliable than two strokes. When they stop they stop. One wont do it any more than the other. The noise thing, anything over 25 knts, all you hear is the wind thundering past your ears . So what does it matter what's hanging off the back. Personally I prefer a two stroke. The power delivery lb for lb is superior. As for fuel? The difference is not worth worrying about with a modern HPDI.

4 strokes are better at low speed work arnt they? my honda runs all day without a sniff or a snort on the river speeding along at 5 mph, not sure what optis and hpdis are like doing this, if the chap does lots of fishing or trolling or plodding around this might be a consideration.

[Richard B]

Good point, however our Yammie HPDI runs all day at tickover without complaining. A four-stroke would be almost silent at tickover though.

[Hightower]

Excuse my ignorance but why do so many people think that engine weight is an issue when buying a new Outboard? Sure you have to follow the recommendation of the RIB builder for the transom weight but does say 40kgs make that much difference?

When I replaced my outboard earlier this year I went from a 80hp 2 stroke that weighed about 135kg to a rather portly 90 Merc 4 stroke that weighs in at 175kg's. I get better handling and more performance and better economy as well as lower noise when I'm pottering around, on the negative side.......The throttle lever control sucks.

[Mollers]

My Opti will troll at tickover ( 2.9 knts, perfect mackerel speed) all day and not cough once. Not quite silent, but a none to unpleasant kind of two stroke rattle! . No seriously, it's fine at tickover.

[Mollers]

Originally Posted by Hightower

Excuse my ignorance but why do so many people think that engine weight is an issue when buying a new Outboard? Sure you have to follow the recommendation of the RIB builder for the transom weight but does say 40kgs make that much difference?

When I replaced my outboard earlier this year I went from a 80hp 2 stroke that weighed about 135kg to a rather portly 90 Merc 4 stroke that weighs in at 175kg's. I get better handling and more performance and better economy as well as lower noise when I'm pottering around, on the negative side.......The throttle lever control sucks.

...and your missus has to sit with her arse hanging over the bow all day!

[Richard B]

Originally Posted by Hightower

engine weight is an issue when buying a new Outboard?

Depends how hard you drive it. Once you become airbourne, you want to fly straight and true. Landing R-send first isn't comfortable. And a tail-heavy RIB in a head sea is really, really tedious.

[Hightower]

Originally Posted by Mollulnan

...and your missus has to sit with her arse hanging over the bow all day!

Don't be nasty.........

We always get lot's of reports of Mermaids in the area when she does....Or was it Whales!.....I never can remember!