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Old 08 July 2012, 10:09   #1
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Choice of two engines. Advice please.

We have an Avon Searider 4m and currently have a 15hp Yamaha 4-stroke manual start. We would like to change this for an electric start outboard. Although the primary use for the RIB is as a tender to our sailing boat, we would also like to make a few longer trips outside the River Dart for which a little more power would probably be useful.

We are looking at 2 different engines - one is a Yamaha 25hp high-thrust 4-stroke complete with power trim etc. The other is a 30hp oil-injected Yamaha 30hp 2-stroke. The 2-stroke is around half the price of the 4 but has no power trim etc. I am sure that either would do the job outside the harbour but would the 2-stroke continually oil up when in tender-mode (under 6 knots).

Anybody any ideas on the relative fuel consumption of the 2 engines ?

Suggestions and views please !

TIA
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Old 08 July 2012, 10:21   #2
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Originally Posted by kdog View Post
I am sure that either would do the job outside the harbour but would the 2-stroke continually oil up when in tender-mode (under 6 knots).
I have a 20HP 2-stroke Yam with autolube - never had a problem with plugs fouling running at low speed, as I assume the mix is adjusted according to engine revs. I don't know if there is a right/wrong answer to your question.
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Old 08 July 2012, 11:18   #3
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Wont you use more petrol not trimming on the move, as I have just learnt. Or is that not a major problem as it only a river and doesnt get too choppy??
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Old 08 July 2012, 11:24   #4
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Been a tight Yorkshireman I'd go for the two stroke!
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Old 08 July 2012, 11:37   #5
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I had a Yam 20hp 2 stroke with auto lube from new and kept it for 10 years. I used it quite a bit in both fresh water and sea. Whatever the revs, it never missed beat.

Hope my Mariner 80efi behaves the same
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Old 08 July 2012, 13:03   #6
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<quote>Been a tight Yorkshireman I'd go for the two stroke!</quote>


i bet you would darling ! lol
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Old 08 July 2012, 16:55   #7
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The power trim would make my choice
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Old 08 July 2012, 17:38   #8
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Prior to 4 strokes coming along, was there a problem with engines oiling up ?

My answer would be not if you had the correct mix, and had the engine serviced correctly.

I would go for the 2 stroke !!
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Old 09 July 2012, 04:00   #9
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Thanks, everyone for the replies. Plenty to think about.

Cheers,

Colin
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Old 10 July 2012, 05:32   #10
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Oil injecton on those is variable mix - so when at idle it runs at something like 200:1, and only goes 50:1 at or near WOT. Hence not oiling up. It's the old premix machines that have a tendancy to do that.

If it were me, even on the river with the currents I vaguely remember seeing last time I was down there, I'd go for the extra 5 gee gees & get the 2-stroke.
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