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Hi
I have a 1985 90 hp Yamaha on a 1985 24' Fiberglass Skipper Craft Pontoon Boat. The boat weight is around 2800 pounds when ready for a day on the water.
I am only getting 4900 rpm at wide open throttle and a speed of 19.8 mph on GPS with the motor trimmed to its best performance spot, if trimmed up from this location it blows out or cavitate's, if trimmed down I loose MPH and RPM.
The Motor is mounted on the boat so the cavitation plate is even with the bottom of the pontoons and it has the stock prop on it to the best of my knowledge. The only number I can find on prop is a 14 K stamped on it.
Can some one tell me what prop I have and which way to go pitch wise to obtain better performance. I am not looking to go fast . But it seems my RPM are lower than they should be.
What is the max RPM for this motor ? I would like to try and get better fuel economy and maybe a few MPH by getting RPM up and not have to run wide open throtle.
Thanks for reading my info and for any help that is offered.
I have a 1985 90 hp Yamaha on a 1985 24' Fiberglass Skipper Craft Pontoon Boat. The boat weight is around 2800 pounds when ready for a day on the water.
I am only getting 4900 rpm at wide open throttle and a speed of 19.8 mph on GPS with the motor trimmed to its best performance spot, if trimmed up from this location it blows out or cavitate's, if trimmed down I loose MPH and RPM.
The Motor is mounted on the boat so the cavitation plate is even with the bottom of the pontoons and it has the stock prop on it to the best of my knowledge. The only number I can find on prop is a 14 K stamped on it.
Can some one tell me what prop I have and which way to go pitch wise to obtain better performance. I am not looking to go fast . But it seems my RPM are lower than they should be.
What is the max RPM for this motor ? I would like to try and get better fuel economy and maybe a few MPH by getting RPM up and not have to run wide open throtle.
Thanks for reading my info and for any help that is offered.
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