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 ?
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.
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??
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.
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.
