My rpms will not go over 4800

[tmt]

Hello, I have tryed some things with the prop. Thread in prop section http://forums.iboats.com/showthread.php?t=381752

Others

Compression check 110/110/110/105
Decarbed
new plugs
set WOT timming
made sure carbs were opening all the way
checked tach with tack on timming light

Next I am going to check:
Lower unit oil
Spark
Fuel pressure

The motor is a Johnson 115 SPL 1997
Boat is a 1997 Wellcraft 190CCF
Motor starts easy, good hole shot, good midrange power.
But top RPM is 4800 and I need to get 5500.
Anything else I shoud look at?

t

 

[tashasdaddy]

Re: My rpms will not go over 4800

compression is about right, but i think you are a little under powered the boat weights Dry 2350. the only thing you can do is get it propped correctly, and trimed out correctly.

 

[kenmyfam]

Re: My rpms will not go over 4800

Agree with TD. Prop it down in pitch till you get the desired WOT. This is assuming your set up is at it's optimum (motor height, trim, loading etc)

 

[wilde1j]

Re: My rpms will not go over 4800

If Cav plate is under water @ WOT, you can move motor up at least one hole, which will increase RPM and speed, as well as improve fuel economy. Keep coming up until the cav plate is uncovered and you don't get excessive cavitation in turns at high power settings.

If RPM is still too low after you get motor height right, start lowering prop pitch.

Raising (or lowering) the motor if you trailer (or have access to one) is very easy.

 

[kenmyfam]

Re: My rpms will not go over 4800

When raising the motor make certain that you have enough cooling water getting through though.