I'd agree with Ron 100% on this as a possible cause. I guess I assumed the YT was the "twin" to my Johnson Sailmaster. Funny that none of the manufacturers still make dedicated sailboat motors....for displacement boats that never operate at speed, and could used fixed throttles and low pitch, high thrust generating props. If you buy a new motor now, what do you folks do to get the prop right? On Jul 19, 2008, at 11:50 AM, Ronnie Keeler wrote:
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