Hello,<br />I have a custom fiberglass 25 foot panga, Eduardono style, beefed up, with double floor and some additional fiberglass lockers, ankle locker, live well. Additional weight to this would be some 1300lbs between people, fuel and equipment.<br />The engine is Yamaha V4 140HP two stroke outboard, from around 96 or 97. As far as I know this model was not sold in the US.<br /><br />With the 21 pitch aluminum prop the acceleration is very slow. Once on plain, she gets to some 36mph at 4600rpm (full throttle), the engine runs very well. The RPM range for the engine is 4500-5500. Still, the max RPM never gets to engines theoretical 5500 rpm.<br /><br />We tried 19 pitch stainless steel prop, we got better acceleration, but surprisingly no max RPM change, still some 4600 max at about 33-34 mph (slightly lower max speed comparing to 21). We did not get the expected 400rpm change.<br /><br />Id appreciate any suggestion, what could be the matter? Thanks.
