low rpm

[ebramlett]

I just installed a 1993 90 hp on a 22ft pontoon cranks and runs fine but can only get 2800 rpm engine was previously on a17 ft challenger bass boat ,prop is 13 3/4 x21 four blade alum. could this be my problem, any suggestions welcome and thanks

[Sequoiha]

Yes, a 21 pitch prop on a pontoon with a 90 aint gonna cut it,, you should probalby pictch down to a 17 or lower,,

[ebramlett]

thanks

thank you ,do you recommend 3 or 4 blade