Speed & Rpm

[tsubaki]

I agree with everybody, low speed and low rpms.
I'm scooting along at 43mph with a 14x19 prop at 5100rpms.

[Destroyer]

As a rule of thumb, every downward pitch change should get you an extra 400-600 rpm... so a 21 to a 17 sounds like it should do it.

[THEFERMANATOR]

Originally Posted by Destroyer

As a rule of thumb, every downward pitch change should get you an extra 400-600 rpm... so a 21 to a 17 sounds like it should do it.

Divide your numbers in half and your there. Every inch of pitch should equal roughly 200-300 RPM's.

[joeturse]

The prop on her now is a Stainless 14 1/4 X 17.Need to check my tach out.I think that it may not be accurate.

[Mulv80]

I have a 2000 Johnson 150 with full fuel and (2) 225lb adults she'll do 42 mph at 5500 rpm.

[tsubaki]

That prop should be about perfect.
Does the possibility exist that the motor may need to be decarboned? Say with Seafoam or the like.
I just got through outfitting a boat for my daughter and her husband (and the grandkids) with a motor I'd had for years. When I first got the motor it would idle and run good to great but never seemed to have the top end speed I thought it should have, changing plugs, props, etc, never solved the problem. When I put it on the other boat it performed the same till I fogged the carbs a few times and started mixing Seafoam in the fuel. It is slowly improving and turning a little more rpms running wide open than what it used to.

[joeturse]

Seafoam sounds like a good suggestion.I will give it a try.This is my first outboard,I have owned I/Os in the past.
I was pleased with the performance of the motor,other than the low RPMs.
She would jump up on plane fast.Guess you call that a good hole shot.