Johnson 4 prop options ?

[Lowranger]

1999 -J4REEA-twin 2-stroke. On my Achilles LSI 77(7'7") inflatable my best speed was 4500 rpm with the original 7 1/2 x 7 plastic prop (#319774). The manual says that the recommended max range is 4500-5500. On this website I've learned that the pros like to see a motor propped at or near the top of the range. The propfinder here at the marine store offered no options. Not even the stock one. On another website I found a 7 1/2 x 6 with part #0318487. How much is a 1" pitch reduction going to increase my rpm ? Are there other props available that will get me closer to 5500 rpm ?

 

[Scaaty]

Re: Johnson 4 prop options ?

Its only a 4hp...what ya got is fine...its the boat weight in front that will slow ya down..

 

[Lowranger]

Re: Johnson 4 prop options ?

Thanks Scaaty, It DOES push a bow wave when I ride up there. If I don't the bow points skyward and progress is slower. In fact, she runs fastest when I center the tiller, crawl forward, and steer by shifting my weight side-to-side. I'm guessing 6,7, or 8 mph. Not quite planing (semi-displacement ?). So I understand, are you suggesting that a smaller pitch will NOT raise my rpm. I'm not looking for more speed. I just don't want to lug my little motor.

 

[steelespike]

Re: Johnson 4 prop options ?

Thanks Scaaty, It DOES push a bow wave when I ride up there. If I don't the bow points skyward and progress is slower. In fact, she runs fastest when I center the tiller, crawl forward, and steer by shifting my weight side-to-side. I'm guessing 6,7, or 8 mph. Not quite planing (semi-displacement ?). So I understand, are you suggesting that a smaller pitch will NOT raise my rpm. I'm not looking for more speed. I just don't want to lug my little motor.

In this case you are not lugging the nmotor you are just at the bottom of the rpm band.
You could try raising the motor ,if you could get an inch higher you could gain some rpm,probably 50 or 100 rpm.Not much because of the displacement type operation.