Andrei,
I had a Yachtwin 4 hp on my old Balboa 20 and had similar problems. The
solution was to change the prop to what Evinrude called a ""power prop". The
stock prop on that motor was probably intended for a light john boat or small
dinghy. The flatter the pitch, the lighter the load on the motor and the
higher it will rev. Two cycle motors don't deliver much horsepower at low RPMs
and your motor should run at maximum RPM at Wide Open throttle with a light
load in the boat.
Iboats website has a prop selector guide that may have your motor listed and
the recommended prop for heavy load applications. My 21 foot pontoon boat was
not performing well with the origonal 16 pitch prop that came with the 40 HP
Mercury and I used the iboats prop guide to determine that I need a 9 or 10
pitch prop. The boat performs best with the 10 pitch when lightly loaded and
best with the 9 when loaded with a half dozen or more people.
I have a longshaft full gearshift Evinrude 4hp on my M17 which works very well
but it has the "power Prop".
Ron
M17 #14
Griselda
> From: [EMAIL PROTECTED]> To: [email protected]> Date:
> Sat, 19 Jul 2008 09:35:02 -0500> Subject: M_Boats: Is my outboard in
> trouble?> > Hello all,> > I have a question on my 4hp Evinrude outboard.
> Yesterday, in a no-wind > situation, the boat (M-17) was barely moving with
> the power at > maximum. Maybe I was getting 2 knots, at best. What did seem
> strange > was that when I moved from one side of the boat to another, the
> prop > seemed to rev up, as if just by shifting the weight and lifting >
> slightly the motor, the prop was about to cavitate. As it is mounted > right
> now, on the original (1982) motor mount, the motor is in the > water up to
> the bottom cavitation plate, just above the water pump > intake.> > Is the
> problem the motor itself, or the fact that the motor is not > deep enough in
> the water? It seemed to run fine except for the lack of > power/speed. It is
> the original motor that came with the boat, 1981 > Yachtwin, the boat is
> 1982 M-17.> > To give you an idea, with my Compac 16 (lighter, 1100 lbs
> versus 1600, > but still), a Johnson 3hp was pushing it at hull speed with
> only 60% > power.> > Thanks for all input,> > Andrei.> > >
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