Too much oil

[Nason]

What engine do you have? What is it running on? What rpms are you wanting to get to? As "Powerboat" notes the mixes you are using are 40 and 47:1 which are not oil excessive.
Race engines that I have read about here, on Hydroracer, in PM's and elsewhere state as rich as 9:1 to about 40:1. As stated above more oil helps seal the rings for more power which is corroborated by tests down to about 18:1. Usually excessive oil also is to let parts live longer, and as has been stated oil is cheaper than parts. Higher rpm requires more oil.

The motor is a merc 40 hp triple 59 ci that has been cut on. The boat is a 15 x 48 weld built, I would like to reach 7500 - 7800 rpms.. The motor is just broken in and I'm trying to fine tune it. From 0 to 6500 rpm its pretty quick but kinda slow getting to 7000 rpms.

[zul8tr]

So not a race boat, is weld built aluminum? A 15 x 48, is that ft x inches wide? Easy to reach 7500+ rpm just reduce pitch and diameter but no guarantee that it willl be the correct prop for the set up and you just have an over reved engine and poor speed. You need to sneek up on the correct prop for your setup for the rpm and speed target. For each prop try different heights and different prop shaft angles, record results of speed (gps ideal, water pickup next best) and rpm. Run in 2 directions. Check out in turns. Record oil ratio and fuel using. Try different oil ratio and see what happens. Does the carb have adjustable high speed? Speed usually increased with increased height and correct shaft angle, there is a limit for each prop for a specific hull and water conditions. You need to find that limit.

You can estimate prop slip knowing rpm, speed, gear ratio and pitch using:

http://continuouswave.com/cgi-bin/propcalc.pl

If you can get 5% or less you are doing excellent but, I expect you will get to the near 10% slip performance unless you have a very light hull that you can get a lot of it out of the water to reduce the water drag.

Repeat with a different prop

Tedious work no easy out here.

[BRzuki]

You need my little merc chopper in the classifieds Nason! Put a hub in it and 7500 shouldn't be any problem once the motor loosens up a little.